Co-occurring alcohol/other drug (AOD) and mental health conditions are highly common (47–100%) (Kingston et al., 2017) and represent a significant challenge in the AOD treatment setting. Among people presenting for treatment, these co-occurring conditions often result in more complex and severe clinical profiles (Lozano et al., 2017; Mills et al., 2018; Teesson et al., 2015) and can complicate the course of treatment as they interact in ways which may trigger, exacerbate, or maintain one another (Marel et al., 2016; National Institute for Health and Care Excellence, 2016; Substance Abuse & Mental Health Services Administration, 2020).

Managing co-occurring AOD and mental health conditions is also challenging for AOD workers as people experiencing these conditions can be harder to engage and retain in treatment (Krawczyk et al., 2017; Olfson et al., 2000). It is unsurprising then that there is some, albeit mixed, evidence that people with co-occurring AOD and mental health conditions experience poorer treatment outcomes than people without co-occurring conditions (Hersh et al., 2014; Wolitzky-Taylor et al., 2015). Given the high prevalence of mental health conditions among people seeking AOD treatment and the challenge they present to treatment providers, there has been increasing emphasis on the management of this comorbidity in clinical guidelines.

Clinical practice guidelines summarise evidence-based recommendations and are an important tool in improving workforce capacity, facilitating the delivery of evidence-based treatment, and enhancing client outcomes. A recent systematic review examining the effectiveness of evidence-based guidelines for patients with mental disorders found that guideline-adherent treatment resulted in greater improvements and quicker time to remission for patients, compared to treatment as usual (Setkowski et al., 2021). Moreover, there was also a correlation between patient well-being and provider adherence to guideline recommendations, highlighting the important role of provider behaviour at improving patient outcomes in mental health (Setkowski et al., 2021). As a crucial first step in the development of up-to-date clinical practice guidelines for managing co-occurring AOD and mental health conditions, namely the next edition of the Australian National Comorbidity Guidelines (Marel et al., 2016), there is a need to synthesise the published literature to inform an evidence-based core set of guiding principles for frontline AOD workers.

To this end, we undertook a scoping review of the published literature on guiding principles for managing co-occurring AOD and mental health conditions in AOD treatment settings. Guiding principles encompass both values and strategies which set a standard for behaviour and decision-making within an organisation or workplace, in this case workers and providers managing people with co-occurring mental health conditions within AOD treatment services. These principles are “guiding” insofar as they are not prescriptive, rather they are broadly generalisable recommendations which can be flexibly applied within different alcohol/other drug treatment services (e.g. outpatient, rehabilitation) and help to provide a framework for how people approach working with clients with co-occurring mental health conditions. Specific aims for this review were to synthesise published knowledge on (1) the key guiding principles for managing co-occurring AOD and mental health conditions in AOD treatment settings and (2) the potential linkages between the key guiding principles and (i) symptom-related outcomes (e.g. AOD use, mental health symptoms) or (ii) other outcomes relevant to treatment (including but not limited to satisfaction with care, treatment engagement). Both quantitative and qualitative literature were included to provide a broader, more comprehensive account of key guiding principles, by incorporating both findings of efficacy and effectiveness with clients’ and treatment providers’ experiences and perspectives.

Methods

Study Design

We undertook a scoping review as there are no known previous reviews on this topic, and due to the expected heterogeneity of the available evidence (Peters et al., 2015). Accordingly, as a scoping review, an assessment of the quality of articles was not within the scope of the current review. Guided by Arksey and O’Malley’s (2005) framework, we developed a systematic search strategy protocol based on the PI(E)COS framework and reported according to the PRISMA framework (Liberati et al., 2009; Tricco et al., 2018). To ensure findings were relevant to contemporary clinical practice, literature sources were restricted to publications from 2010 onwards.

Search Strategy

Articles were identified through searches of key electronic databases in medicine, psychology, and public health (MEDLINE, EMBASE, PsycINFO, and Scopus). The review team also conducted manual forwards and backwards snowballing searches, which involved screening articles which cited the final included articles (via Google Scholar) and screening articles included in the reference lists of the included studies. This process helped ensure a comprehensive assessment of the literature. Search results were limited to studies published in English, comprising human participants, between January 1, 2010, and February 17, 2021.

Initial keyword search strategies were guided by recent systematic reviews exploring the treatment of co-occurring AOD and mental health conditions (Fisher et al., 2021; Kingston et al., 2017; Mental Health and Drug and Alcohol Office, 2015), and relevant clinical practice guidelines (Marel et al., 2016; National Institute for Health and Care Excellence, 2011, 2016; Substance Abuse & Mental Health Services Administration, 2020). These strategies were then refined in discussions with the review team and a specialist academic librarian, a senior clinical psychologist with expertise in the treatment of co-occurring conditions, and a person with lived experience of co-occurring AOD and mental health conditions. Including a lived experience perspective was important to ensuring that the “guiding principles”-related keywords and phrases also captured the views and experiences of people receiving treatment, which were expected to be covered in the qualitative literature especially.

The final search strategies included a combination of free-text terms and subject headings, which were adapted to each database. Adjacency terms were also used to increase the flexibility and coverage of searches. Various search terms were used incorporating key conceptual domains (see Box 1 for an example search query used for MEDLINE):

  1. 1)

    Alcohol and other drug-related terms (see lines 1 to 4 in Box 1)

  2. 2)

    Mental health-related terms (see lines 5 to 7 in Box 1)

  3. 3)

    Comorbidity or co-occurring condition-related terms (see lines 8 to 10 in Box 1)

  4. 4)

    Guiding principle-related terms (see lines 11 to 13 in Box 1)

Box 1 MEDLINE search strategy example

1. alcoholism/

2. exp Substance-Related Disorders/

3. ((abuse* or misuse* or dependenc* or addict* or disorder* or problem* or hazard* or harm* or risk*) adj4 (substance or sud or drug* or alcohol* or amphetamine* or cannabis or marijuana or cocaine or inhalant* or hallucinogen* or phencyclidine or heroin or morphine or opioid* or stimulant* or tobacco or sedative* or hypnotic or anxiolytic*)).tw

4. 1 or 2 or 3

5. exp Mental Disorders/

6. (depress* or dysthymi* or mental disorder* or mental illness* or psychological disorder* or psychological illness* or psychiatric disorder* psychiatric illness* or psychopatholog* or mood disorder* or affective disorder* or bipolar* or cychlothymi* or mania or manic or hypomania or anxiety disorder* or gad or panic disorder* or agoraphobi* or phobi* or obsessive–compulsive disorder or ocd or body dysmorphic disorder or bdd or hoarding disorder or trichotillomania or hair-pulling disorder or excoriation disorder or skin-picking disorder or post traumatic stress disorder or ptsd or trauma or acute stress disorder or adjustment disorder or psychotic or psychosis or schizo* or delusional disorder or dissociative disorder or conversion disorder or depersonali?ation disorder or dereali?ation disorder or psychosomati* or somati* or somatoform or eating disorder* or feeding disorder* or anorexi* or bulimi* or oppositional or defian* or conduct disorder* or pyromania or kleptomania or disruptive disorder or impulse control disorder or personality disorder* or attention deficit hyperactivity disorder or adhd or attention deficit disorder).tw

7. 5 or 6

8. exp Comorbidity/ or diagnosis, dual (psychiatry)/

9. (comorbid* or “dual diagnos*” or co-occur* or co-exist* or concurrent).tw

10. 8 or 9

11. Practice Guideline/

12. (guideline* or "practice guide*" or "guiding principle*" or "care principle*" or "principles of care" or "best practice" or "practice guideline*" or "treatment model*" or "care model*" or "model of care" or "pathway of care" or "care pathway" or "therapeutic model*" or "treatment approach*" or "care approach*" or "therapeutic approach*" or "therapeutic alliance" or "therapeutic relationship" or "professional development" or "access to care" or "no wrong door" or holistic or client-cent?red* or person-cent?red* or client engagement or recovery-oriented or "recovery oriented" or trauma-informed or individuali?ed or "individually tailored" or collaborative or non-judgemental or non-judgmental or con-confrontational or "shared decision-making" or rapport-building or "rapport building" or "peer-work*").tw

13. 11 or 12

14. 4 and 7 and 10 and 13

15. limit 14 to (humans and english language and yr = "2010 -Current")

Data Screening

Selection procedures were based on PRISMA guidelines (Liberati et al., 2009). All data screening was completed using Covidence (www.covidence.org). After removing duplicates, two reviewers independently screened titles and abstracts for potential inclusion using the specified eligibility criteria (see Table 1). The two reviewers met after screening a random selection of 100 articles to ensure that reviewers were interpreting the eligibility criteria in the same way. When reviewing the titles/abstracts of articles, those articles identified as potentially eligible by at least one reviewer (i.e. ‘yes’ or ‘maybe’ include) were automatically included for full-text screening. Full-text screening was conducted by the lead reviewer. This liberal approach to article inclusion at the title/abstract screening stage was done given the at times, limited, and inadequate information provided in the article’s abstract to determine inclusion, especially with regard to if the article addressed guiding principles and processes. Throughout the data screening process, discrepancies were resolved in discussion with other members of the review team; for example, when the lead reviewer was unsure about the eligibility of an article based on full-text review.

Table 1 Eligibility criteria
Full size table

Data Extraction

Study level data from the final included articles were extracted by one reviewer and verified by the lead reviewer. Disagreements were resolved through consensus with the broader review team. Data extracted included study design and methodology, participant setting and sample, guiding principle-based recommendations, intervention and control details, and relevant outcome data. The data extraction proforma was initially piloted using 5 articles (~ 10% total included) to ensure common understanding and use.

Data Synthesis

Findings from the included articles were categorised according to common scope and overall themes. Categories were then labelled as guiding principles by AF and SEDR using inductive (data-driven) and deductive (literature-driven) approaches, and refined through discussions with the other review team members. All symptom-related (e.g. AOD use, mental health symptoms) and other outcomes (e.g. satisfaction with care and treatment engagement) are synthesised descriptively and presented after the main guiding principle recommendations.

Results

Database searches returned 4583 articles. After removing duplicates, 2709 articles were title/abstract screened for eligibility, resulting in 106 articles for full-text screening (see PRISMA flowchart in Fig. 1). Full-text screening left 36 eligible articles. Forward and backward reference searches of eligible articles generated an additional seven articles for inclusion, resulting in a total of 43 articles.

Fig. 1
figure 1

PRISMA flow diagram

Full size image

Study Characteristics

Table 2 outlines the study characteristics, including study design and methodology, participant setting and sample, the main elements of the guiding principle described, intervention and control details, and results.

Table 2 Tabulated summary of included guiding principle study findings
Full size table

Key Guiding Principles

Fifteen guiding principles were identified in the thematic analysis, which are described below along with the number of articles presenting findings related to each principle.

Build a Strong Therapeutic Relationship (n = 24)

When working with clients with co-occurring AOD and mental health conditions, there was evidence from several articles of instances when AOD workers developed strong therapeutic alliances. A strong alliance encompassed interactions that were welcoming, genuine, optimistic, and respectful (Haskell et al., 2016; Kendall et al., 2011; Lubman et al., 2011; McCallum et al., 2016; Motta-Ochoa et al., 2017; Pettersen et al., 2014; Staiger et al., 2011). In one cross-sectional survey study of healthcare providers working in comorbidity services (n = 250), approximately 70% indicated that the therapeutic alliance was the most important element to consider for improving clients’ prognosis (Roncero et al., 2016). Several qualitative studies presented similar findings, with clients valuing the quality of therapeutic relationships in achieving recovery, and preferring empathetic providers who view them as whole people (Haskell et al., 2016; McCallum et al., 2016; Motta-Ochoa et al., 2017; Stott & Priest, 2018; Topor et al., 2019). To strengthen the therapeutic relationship, three literature reviews and two qualitative studies among clients and providers of comorbidity services noted the need to flexibly balance validating and challenging the client (Donald et al., 2019; Kendall et al., 2011; Lubman et al., 2011), and ensuring that contact is consistent and continues throughout the referral process (Hoxmark & Wynn, 2010; Staiger et al., 2011).

Building a strong therapeutic relationship was also highlighted in several studies of specific populations, involving young people, those identifying as female, LGBTIQ + , Aboriginal Australian and Torres Strait Islander people, and those involved in the justice system (Abraham et al., 2017; Crockford & Addington, 2017; Hawke et al., 2019; Hulvershorn et al., 2015; Lee et al., 2014; Ness et al., 2014, 2017; Penn et al., 2013; Silverstein et al., 2021; Tilbury, 2017; Tompkins & Neale, 2018).

Within specific populations, one scoping review and several qualitative studies of AOD treatment providers and clients reported that a relationship which is welcoming, optimistic, authentic, and respectful of clients’ autonomy can encourage motivation and adherence to treatment among client groups who may distrust healthcare providers, such as young people, women, and those involved in the justice system (Hawke et al., 2019; Ness et al., 2017; Tilbury, 2017; Tompkins & Neale, 2018). Non-judgemental and accepting attitudes were also described as essential for providers to ensure that often-stigmatised groups (i.e. LGBTIQ + clients or those with psychotic symptoms) develop treatment goals that are consistent with individual needs (Crockford & Addington, 2017; Penn et al., 2013). Additionally, one qualitative study and a scoping review noted that clients appreciated when providers incorporated elements valued by their communities, such as being flexible and friendly when caring for Aboriginal Australian women (Lee et al., 2014) or using language familiar to young people (Hawke et al., 2019).

Provide Holistic Care (n = 12)

In four qualitative studies, people with co-occurring conditions spoke about the importance of AOD workers considering their AOD use alongside co-occurring mental health conditions and other medical, family, and social needs (Haskell et al., 2016; McCallum et al., 2016; Motta-Ochoa et al., 2017; Staiger et al., 2011). Across these studies, clients expressed a preference for treatment that is tailored to their broader needs and provides opportunities to practise skills for personal development (e.g. skills for obtaining work or housing, or developing social connections) (Haskell et al., 2016; McCallum et al., 2016; Motta-Ochoa et al., 2017; Staiger et al., 2011).

Findings from studies involving specific populations also supported the use of holistic care approaches when caring for people who are young, from culturally or linguistically diverse backgrounds (CALD), LGBTIQ + , or experiencing homelessness (Foster et al., 2010; Kour et al., 2020; Kozloff et al., 2013; Ness et al., 2014, 2017; Penn et al., 2013; Posselt et al., 2017; Silverstein et al., 2021). In these studies, holistic care included multiple components, such as providing support for everyday challenges (e.g. building skills to manage finances or clean a household), basic needs (e.g. finding housing or food), or other issues which are important to the client (e.g. discussing sexual or gender identity). In particular one mixed-methods study conducted among providers and refugee youth from a comorbidity service, participants felt that holistic care was essential to treatment engagement and the development of strong relationships with providers (Posselt et al., 2017).

Involve Peer Support (n = 7)

In two qualitative studies, clients with co-occurring AOD mental health conditions reported that peer support encouraged them to feel part of a community and provided opportunities to learn from others with lived experience (Haskell et al., 2016; Stott & Priest, 2018). ‘Involving peer support’ was also valued in the treatment of clients involved in the justice system or experiencing homelessness, with both providers and clients describing that it helped to welcome clients and encourage them through treatment (Foster et al., 2010; Johnson et al., 2015; Kozloff et al., 2013; Tilbury, 2017).

Ensure Continuity of Care (n = 6)

Findings from three studies using different methodologies all corroborated the importance for AOD workers to use continuity of care practices when working with people with co-occurring mental health conditions. These studies included a systematic review, a cross-sectional survey, and one qualitative study (McCallum et al., 2015, 2016; Merkes et al., 2010). Continuity of care ensured staff were dependable (i.e. limiting changes of staff and appointment cancellations within clients’ treatment), had appropriate discharge policies and procedures, and co-ordinated with a range of support services. In qualitative interviews, clients with co-occurring conditions felt these practices were important to overcome barriers to accessing treatment (McCallum et al., 2016).

Continuity of care was also identified as useful for clients involved in the justice system, to support them from intake through to discharge, and in particular transition into the community (Eagle et al., 2019; Johnson et al., 2015). In the justice context, healthcare providers expressed support for continuity of care practices that (i) maintain contact with the same provider before and after release; (ii) provide support 24–72 h after release; (iii) address lapses before they escalate; and (iv) offer long-term support (Johnson et al., 2015). Post-discharge support was also valued by CALD clients, as aftercare was considered a means of relapse prevention, particularly for those who had experienced stigma-related help-seeking difficulties with their communities (Kour et al., 2020).

Support the Professional Development and Competence of Workers (n = 6)

A review of guidelines recommended that AOD workers have the requisite knowledge and skills to identify mental health conditions which commonly co-occur with AOD use, and appropriately manage and refer clients when needed (Kendall et al., 2011). In a survey of Australian comorbidity treatment services following ‘best practice’ (i.e. identified through a consultation with key stakeholders as services which achieve ‘good outcomes’ for clients with comorbidity), all staff were trained in identifying co-occurring conditions and most in referral procedures (Merkes et al., 2010). Additionally, staff education and training were perceived as an important by clients from CALD, Australian Aboriginal and Torres Strait Islander, or LGBTIQ + communities (Kour et al., 2020; Lee et al., 2014; Penn et al., 2013; Posselt et al., 2017). For example, in qualitative interviews of CALD clients, participants reported greater treatment satisfaction when they perceived providers as more multi-culturally competent (Kour et al., 2020).

Provide Trauma-Informed Care (n = 5)

Trauma-informed care is based on knowledge and understanding of how trauma affects people’s lives and the delivery of effective care. Support for the use of trauma-informed care came from two qualitative studies, an interdisciplinary expert meeting, and a scoping review; this approach was reported as helping clients who are more vulnerable to trauma (i.e. female clients, young adults, and those experiencing homelessness) to manage their symptoms and to engage better in treatment (Foster et al., 2010; Hawke et al., 2019; Silverstein et al., 2021; Tompkins & Neale, 2018). One narrative literature review highlighted the importance of AOD workers establishing a safe place for their clients from the beginning of care, so as to provide them the opportunity to discuss their experiences of trauma should they wish to (Dass-Brailsford & Myrick, 2010). This same review argued that AOD workers introduce the topic of trauma and that discussing clients’ trauma take place over time, as clients sometimes prefer disclosing memories in fragments (Dass-Brailsford & Myrick, 2010).

Provide Recovery-Oriented Care (n = 4)

Using a recovery-oriented approach to care, which is defined as supporting clients’ strengths to achieve their own recovery, was supported by two reviews and two qualitative studies for the treatment of people with co-occurring conditions (Brekke et al., 2018a, 2018b; Brekke et al., 2018a, 2018b; De Ruysscher et al., 2017; DiClemente et al., 2016). In the qualitative interviews, clients reported wanting AOD workers to support their autonomy in decision-making and goal setting (Brekke et al., 2018a, 2018b). To better align care with clients’ personal recovery goals, findings from the two reviews and two qualitative studies suggested that AOD workers focus on the clients’ needs and not their clinical disorder when deciding on treatment (Brekke et al., 2018a, 2018b; Brekke et al., 2018a, 2018b; De Ruysscher et al., 2017; DiClemente et al., 2016). Specifically, review findings noted that recovery-oriented care may be facilitated when AOD workers help clients build peer support relationships and provide discharge support (De Ruysscher et al., 2017).

Tailor Treatment Plans (n = 4)

Findings from two reviews discussed the importance for AOD workers to plan care collaboratively with the client, tailoring treatment to clients’ contexts and readiness for change (Kelly et al., 2011; Kendall et al., 2011). Specifically, one review supported the use of motivational interview techniques for AOD workers to better engage clients in their treatment planning, which may in turn build trust in the therapeutic relationship and promote treatment engagement (Kelly et al., 2011). For justice-involved clients specifically, a review of effective care models in correctional settings provided evidence that collaborating on treatment plans can support clients’ basic needs, preferences, and readiness for change (Eagle et al., 2019). In qualitative interviews, clients and staff from women-only AOD treatment services also spoke about the importance of working collaboratively to ensure clients’ needs are understood for treatment to be tailored (Tompkins & Neale, 2018).

Encourage Patient Autonomy and Shared Decision-Making (n = 3)

Findings from one systematic review and one qualitative study of people with co-occurring AOD and mental health conditions gave support for AOD workers to incorporate patient autonomy and shared decision-making approaches in treatment decisions. Most people with co-occurring conditions reported wanting to take an active and informed role in decision-making and valued being involved in treatment decisions (Fisher et al., 2021; McCallum et al., 2016). Moreover, both clients and providers endorsed shared decision-making interventions as acceptable and feasible to use in practice (Fisher et al., 2021). In qualitative focus groups, female veterans spoke about the importance of AOD staff working collaboratively with clients so as to allow them to voice their needs (Abraham et al., 2017).

Develop Trust with the Client’s Community (n = 3)

Participants in one participatory action research study reported that AOD treatment services should proactively develop a trusting relationship not only with clients, but also with their families, and the broader community (Liu et al., 2016). Establishing trust reportedly helped to encourage more community engagement with reputable and competent services (Liu et al., 2016). It was also viewed as important in qualitative interviews and focus groups of people from Aboriginal Australian or Torres Strait Islander and LGBTIQ + communities (Lee et al., 2014; Penn et al., 2013). Specifically, Aboriginal Australian healthcare workers and women with co-occurring conditions reported that AOD treatment services should build awareness of services within their communities (Lee et al., 2014) while people identifying as LGBTIQ + spoke about the need for treatment services to signal their inclusiveness through specific signage and intake questions (Penn et al., 2013).

Create Collaborative Treatment Goals (n = 1)

A large survey of AOD counsellors working in comorbidity services (n = 751) found that many (71%) considered both clients’ treatment history and individual context when assessing whether non-abstinence was an appropriate treatment goal for clients (Davis et al., 2017). When developing treatment goals, these AOD counsellors reported considering clients’ AOD use history, treatment-related aspects (i.e. client motivation and treatment goals), co-occurring psychiatric diagnoses, and their social and family environment (Davis et al., 2017).

Screen Throughout Care (n = 1)

Review findings supported screening as an important first-step to engaging clients, and one to be conducted throughout clients’ management (DiClemente et al., 2016). This review also supported the use of screening and assessment results to inform collaborative decisions regarding referrals, which involve the client and consider their readiness to change, motivations, and values (DiClemente et al., 2016).

Use a ‘No Wrong Door’ Approach (n = 1)

Findings from one participatory action research study involving surveys, focus groups, and interviews supported the use of co-ordinated, connected, and streamlined care practices for staff working with clients with mental health comorbidity in AOD treatment services (Liu et al., 2016). According to participants, these practices were necessary to ensure clients access appropriate assessment and treatment without unnecessary referrals (Liu et al., 2016). Participants were a diverse mix including staff from local mental health and AOD treatment services, support service workers caring for youth and adults with comorbidity, Aboriginal consumer advocates, Aboriginal and non-Aboriginal workers in mental health and AOD treatment services, and refugee youth and providers of comorbidity-focused refugee youth services.

Involve Families (n = 1)

In a survey of comorbidity treatment providers (n = 250), approximately half reported that family and carer support was important to improving client prognosis (Roncero et al., 2016). Providers also reported considering clients’ family context when deciding on treatment, rating this among the top six reasons for selecting a specific treatment (Roncero et al., 2016).

‘Do No Harm’ (n = 1)

One summary of clinical guidelines discussed the importance for AOD workers to consider the potential harms of treatment options for the client and the community (Arunogiri & Lubman, 2015). These considerations were thought to be especially relevant to the risks of pharmacotherapy use in people with co-occurring AOD and mental health conditions, including interactions between substances, overuse, and the potential for dependence and misuse (Arunogiri & Lubman, 2015).

Guiding Principles and Symptom-Related Outcomes

Three systematic reviews and one pre-post study of interventions examined the potential linkages between four guiding principles and symptom-related outcomes.

AOD Use and Mental Health Symptoms

Firstly, interventions designed to promote guiding principles ‘involve peer support’ and ‘encourage patient autonomy and shared decision-making’ were associated with symptom-related improvements. One systematic review found that peer referrals to peer-support programs (e.g. 12-step), or peer-programs integrated into usual care led to greater improvements in participants’ psychiatric symptoms and reductions in AOD use compared to usual care from baseline to 6 and 12-month follow-up (Eddie et al., 2019). Additionally, another systematic review found that interventions designed to increase shared decision-making led to greater improvements in mental health symptoms from baseline to 3 and 12-months follow-up compared to usual care (Fisher et al., 2021). However, this review reported mixed results regarding AOD use and abstinence; some studies reported null effects from shared decision-making interventions on addiction severity, AOD use frequency and AOD abstinence at 3-month follow-up, while other studies reported negative effects on AOD abstinence at 3 and 12-month follow-up (Fisher et al., 2021).

Furthermore, one systematic review provided evidence that ‘ensuring continuity of care’ may improve symptom-related outcomes. Here, greater patient and observer-rated continuity of care in treatment was associated with greater quality of life and general functioning, but not psychiatric symptom severity, at 17-month follow-up (McCallum et al., 2015).‘Building a strong therapeutic relationship’ may also be linked to improved mental health symptoms, with one pre-post study demonstrating that therapist-rated therapeutic alliance scores were significantly correlated with change in client’s depression symptoms, but not alcohol use outcomes, from baseline to 12 weeks at post-treatment (Richardson et al., 2018).

Guiding Principles and Other Outcomes

Potential linkages between six of the guiding principles and other outcomes were examined in seven qualitative studies, three systematic reviews, one pre-post study, and one cross-sectional quantitative survey.

Treatment Engagement

One systematic review provided preliminary evidence that ‘involving peer support’ may improve treatment attendance, such that peer referrals to peer-support (e.g. 12-step) or peer-programs integrated into usual care led to greater treatment attendance and service use at 6 months after treatment entry to 1-year follow-up compared to usual care (Eddie et al., 2019). ‘Involving peer support’ was also reported as useful to improving treatment adherence and engagement in qualitative studies of clients involved in the justice system or experiencing homelessness, (Foster et al., 2010; Johnson et al., 2015; Kozloff et al., 2013; Tilbury, 2017). Evidence from another systematic review also showed that ‘ensuring continuity of care’ may influence treatment engagement, such that greater continuity of care (operationalised as number of client visits, number of months engaged in treatment, number of providers, and staff-reported practices of continuity of care) positively correlated with clients’ commitment to treatment and engagement in continuing care, as rated by providers 4 months after treatment entry and at 6-month follow-up (McCallum et al., 2015). ‘Encouraging patient autonomy and shared decision-making’ was also found to support treatment engagement in another systematic review, as more participants who received shared decision-making interventions received alcohol-related care and obtained medication supplies compared to usual primary care at 3- and 12-month follow-up (Fisher et al., 2021). Qualitative perspectives from patients and providers in this review indicated that interventions designed to ‘encourage patient autonomy and shared decision-making’ were perceived to facilitate clients’ active involvement in consultations and decision-making (Fisher et al., 2021).

‘Involving families’ in care was also seen to improve clients’ commitment to treatment, with comorbidity service providers rating patient and family psychoeducation as the second most important strategy for treatment engagement (Roncero et al., 2016). Additionally, in qualitative interviews, people with co-occurring symptoms described experiencing ‘holistic care’, in the form of individualised treatment to support both addiction and psychological challenges, as a positive influence on their treatment engagement and commitment to recovery (Motta-Ochoa et al., 2017). In contrast, ‘building a strong therapeutic relationship’ does not appear to impact treatment engagement and attendance, with one pre-post study showing no relationship between clinician-rated therapeutic alliance and medication adherence or the number of treatment sessions attended (Richardson et al., 2018). Despite this, in qualitative focus-groups, AOD workers reported that trusting therapeutic relationships may encourage treatment engagement by providing clients with opportunities to discuss difficult experiences and learn how to form new positive relationships (Hoxmark & Wynn, 2010).

Satisfaction with Care

In qualitative research, ‘build a strong therapeutic relationship’, ‘provide holistic care’, and ‘ensure continuity of care’ were all linked to greater client satisfaction with care (McCallum et al., 2016; Motta-Ochoa et al., 2017). In terms of therapeutic relationships, clients in qualitative interviews reported feeling more satisfied with staff who they perceived as non-judgemental and empathetic as this helped to reduce clients’ feelings of shame (McCallum et al., 2016). Additionally, one systematic review found support for ‘ensuring continuity of care’ in treatment, such that greater patient and observer-rated continuity of care were associated with increased service satisfaction for patients at 17-month follow-up (McCallum et al., 2015). By contrast, another systematic review reported that interventions to ‘encourage patient autonomy and shared decision-making’ with case managers did not lead to greater care satisfaction among clients compared to usual care (timepoint not reported). In explaining this lack of association, the authors noted that it may be attributable to high clients’ satisfaction ratings pre-intervention, resulting in a ceiling effect (Fisher et al., 2021).

Therapeutic Alliance

In one systematic review, an intervention to ‘encourage patient autonomy and shared decision-making’ with clinicians showed no effect on client-rated therapeutic alliance compared to control both midway and at the end of treatment; however, participants’ alliance ratings were high before receiving the shared decision-making interventions (Fisher et al., 2021). Despite this, shared decision-making interventions were found to increase the client–clinician agreement on treatment goals (at 6 and 12 weeks into treatment) and were viewed clinicians in focus groups to facilitate agreements on treatment decisions with clients, which is an important aspect of the therapeutic alliance (Fisher et al., 2021).

Discussion

This review is the first to synthesise the international published literature on guiding principles for working with people with co-occurring AOD and mental health conditions in AOD treatment settings. Key findings are discussed below, which can inform evidence-based guidance for AOD workers to optimally support people with co-occurring AOD and mental health conditions to engage with and benefit from treatment.

Alignment of These Guiding Principles with Contemporary Clinical Guidelines

The fifteen guiding principles identified in this review align closely with current international guidelines for the management of co-occurring AOD and mental health conditions (National Institute for Health and Care Excellence, 2016; Network of Alcohol & Drug Agencies, 2021; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). For example, international guidelines commonly stress the importance for all clients to receive care regardless of where they present (i.e. ‘use a ‘no wrong door’ approach’), and emphasise that providers should screen for common mental health conditions to ensure they are identified and treated (‘screen throughout care’) (National Institute for Health and Care Excellence, 2016; Network of Alcohol & Drug Agencies, 2021; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). International guidelines also encourage individualised treatment (‘tailor treatment plans’) to address the concerns and needs that matter to the client (‘provide holistic care’) by collaborating with clients to identify recovery goals (‘create collaborative treatment goals’) (National Institute for Health and Care Excellence, 2016; Network of Alcohol & Drug Agencies, 2021; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). Moreover, many guidelines recommend that treatment focus on empowering the client to recognise their own strengths to achieve recovery (‘provide recovery-oriented care’), which may include involving their family (‘involve family’) or collaboration and streamlined referrals to external services (‘ensure continuity of care’) (National Institute for Health and Care Excellence, 2016; Network of Alcohol & Drug Agencies, 2021; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). International guidelines also encourage providers to develop trusting relationships so that their clients can voice concerns without fear of stigma (‘build a strong therapeutic relationship’) and which acknowledge the impact of trauma on clients’ lives (‘provide trauma-informed care’) (Bloom et al., 2003; National Institute for Health and Care Excellence, 2016; Network of Alcohol & Drug Agencies, 2021; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). Finally, these guidelines highlight the importance of ensuring staff have the competence to provide appropriate care and are supported to develop their skills (‘support the professional development and competence of workers’) (Bloom et al., 2003; National Institute for Health and Care Excellence, 2016; Network of Alcohol & Drug Agencies, 2021; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005).

It is important to note that while the fifteen guiding principles aligned with national and international clinical management guidelines for comorbidity, this is not to say that these principles are not applicable to or beneficial for the management of clients with either a standalone mental health or AOD use condition. This said, some of the guiding principles identified in the current review such as ‘no wrong door’, ‘provide trauma informed care’, and ‘support the professional development and competence of workers’ might be taken as especially pertinent to managing clients with AOD and mental health comorbidities. This is because, compared to clients with a standalone condition, clients with comorbidities are disproportionately affected by the siloed nature of treatment and service provision ((Lee & Allsop, 2020) and report especially high rates of exposure to trauma (~ 80%, (Dore et al., 2012), while the workforce expresses unmet training needs to address AOD and mental health comorbidities (Marel et al., 2021).

Use of These Guiding Principles to Expand Contemporary Clinical Guidelines

Some guiding principles identified in this review are less salient within contemporary international guidelines and may inform future revisions. These principles included ‘develop trust with the client’s community’ and ‘encourage patient autonomy and shared decision-making’. While guidelines highlight the importance of collaborating with clients on treatment decisions, they do not describe strategies AOD workers may use such as shared decision-making and/or decision-support tools (National Institute for Health and Care Excellence, 2016; NSW Department of Health, 2009; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). Secondly, while guidelines emphasise learning about non-dominant cultural beliefs and practices to work effectively with CALD clients, they do not concentrate on building trust with the communities more broadly (National Institute for Health and Care Excellence, 2016; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). By providing overlaps with and areas for expanding on contemporary guidelines, the guiding principles identified in this review are a sound basis for informing the practice of AOD workers to meet the needs of people with co-occurring AOD and mental health conditions.

It is noteworthy also that the guiding principles identified in this scoping review appeared to be interrelated, such that various principles of care and their interrelationships were discussed in each study. For example, ‘building a strong therapeutic relationship’ and ‘providing holistic care’ were seen as essential concurrent practices which were highly valued by young adults with co-occurring AOD and mental health conditions in a qualitative interview study (Ness et al., 2017). Moreover, some guiding principles were shown to impact on other principles directly or indirectly. For example, ensuring that AOD workers are ‘supported in their professional development and competence’ was highlighted as critical to their having the skills necessary to appropriately ‘tailor treatment plans’ and ‘build a strong therapeutic relationship’ with clients (Kendall et al., 2011). In this way, using a systems-based approach which focuses on using multiple strategies in combination with one another, rather than a single principle of care undertaken in isolation, is likely to benefit the clinical practice of AOD workers.

Similarly, many of the guiding principles identified in this scoping review reflected the need to care for clients’ general health, which includes but is not limited to their AOD use or mental health. Given the increasing international prevalence of multimorbidity (the presence of two or more chronic health conditions (Britt et al., 2008; King et al., 2018; Pefoyo et al., 2015; van den Akker et al., 2019)), AOD services may need to broaden their treatment scope to include a multimorbidity focus. The guiding principles identified in this scoping review therefore underscore the need for AOD services to shift towards providing comorbidity and multimorbidity-informed treatment, working in conjunction with other community and specialist health services. For instance, comprehensive ‘screening throughout care’ can help identify physical health comorbidities, which in turn, can provide motivation for clients to engage in treatment for those who are concerned about medical complications (McDonough et al., 2021). ‘Providing holistic care’, likewise, encourages AOD workers to address the individual needs of clients, including their experiences of multimorbidity.

Influence of Guiding Principles on Outcomes

In contrast to the substantial body of literature describing principles of care which are perceived as being important for the management of co-occurring AOD and mental health conditions, this review identified scant empirical literature operationalising and evaluating the potential impact of principles on outcomes. Of the fifteen guiding principles identified in this review, only six were evaluated for their impacts on symptom-related outcomes (e.g. mental health symptoms, AOD abstinence) and other outcomes (e.g. treatment engagement, satisfaction with care). As such, it remains unclear whether and the extent to which specific guiding principles are likely to benefit the care of clients with co-occurring AOD and mental health conditions. Also unclear is whether these guiding principles may be appropriate for use in different contexts or specific populations.

It is somewhat surprising therefore that despite the limited empirical evidence available, the guiding principles identified in this review are widely endorsed both in the published literature and in clinical international guidelines (National Institute for Health and Care Excellence, 2016; Network of Alcohol & Drug Agencies, 2021; NSW Department of Health, 2009; Rush, 2011; Substance Abuse & Mental Health Services Administration, 2020; Todd, 2010; Ziedonis et al., 2005). Furthermore, evidence supporting the use of guiding principles for improving comorbidity management was derived from range of study designs, which were mostly qualitative and precluded any firm conclusions. Indeed, ‘involve peer support’ and ‘encourage patient autonomy and shared decision-making’ emerged as the only principles supported by interventional research. The present scoping review did not include an assessment of the quality of the evidence; however, more high-quality research is needed to evaluate the effectiveness of interventions which incorporate these guiding principles at improving AOD use and mental health, and engagement and satisfaction with care.

Limitations

The current findings should be interpreted considering some limitations. Firstly, the heterogeneity of evidence sources precludes definitive conclusions about the benefits associated with each of the guiding principles. Secondly, most of the identified research was qualitative in nature and based on client perspectives in AOD treatment. Without corroborating evidence from larger-scale quantitative studies, it is hard to know whether these guiding principles are representative of clients in treatment for co-occurring AOD and mental health conditions, and/or to clients who do not engage with treatment or drop out prematurely. Thirdly, to be included in the review, it was not a requirement that articles included clients with diagnosed comorbid disorders. This is because clients are often assessed and treated for their ‘primary’ disorder, while even subclinical/subthreshold mental health symptoms or AOD use can negatively impact on the client’s presentation, prognosis, or treatment response (Marel et al., 2016). However, this means that the reviewed findings relate to clients with both threshold and subthreshold level co-occurring conditions and need to be considered as such. Furthermore, as is typical for scoping reviews, this review did not include a quality of evidence assessment and therefore findings have not considered the quality of the evidence on which they are based. Finally, searches were limited to articles published in English and therefore it is possible that relevant articles published in languages other than English were excluded.

Conclusion

This systematic scoping review provides the first-known comprehensive synthesis of the published literature on guiding principles for managing co-occurring AOD and mental health conditions in AOD treatment settings. Given that this client group is highly common within AOD treatment settings and has specific and unique needs, it is important that AOD workers are equipped with the appropriate knowledge and guidance. This review identified fifteen guiding principles, which are consistent with international guidelines for the management of comorbidity. These guiding principles were endorsed by both client and provider perspectives; however, only six were examined for their impact on outcomes. Therefore, much scope remains in building the empirical evidence base on the effectiveness of these principles at improving relevant client outcomes such as AOD use, mental health symptoms, treatment engagement, and satisfaction with care.