Introduction

High incidence of oral conditions were often reported among palliative patients either direct or indirect primary cause such as salivary gland dysfunction in non-Hodgkin’s lymphoma or fatigue which may affect patient’s ability to undertake oral care hygiene [1, 2]. Medical management of palliative conditions such as chemotherapy were often reported which can produce oral complications among these patients [2]. For example, the National Cancer Institute at the National Institutes of Health, United States of America reported that 80% of patients receiving myeloablative chemotherapy will develop oral complications, and palliative drugs such as bisphosphonates and analgesics were associated with oral mucositis and taste disturbance [3].

Early diagnosis and treatment of oral conditions among palliative patients could minimize their pain and suffering [2]. However, evidence shows that 40% of palliative patients lose their ability to communicate their oral health needs. Therefore, they may suffer treatable oral conditions for a prolonged period of time [4], or they may not complain of discomfort in their oral cavity which they believe to be an inevitable effect of their treatment [5]. This may contribute to under-reporting as well as underestimation of oral conditions among palliative patients, which may result in failure among health professionals to completely appreciate the problem. A literature review of oral care for cancer patients in 2001 reported that oral care is given by junior staffs with less experience and the practice needs to be transferred to oncology nurses [6]. Furthermore, a survey of international supportive health care providers (n = 212) (with 35% response rate) recommended to develop evidence-based practice protocol for oral care management [7].

This systematic review aimed to synthesize the published evidence on oral conditions among palliative patients, impact, management and challenges in managing oral conditions among palliative patients.

Materials and methods

Data sources

Search strategy was devised by the research team with chosen five databases in specific period in English language with comprehensive search terms to not omit any relevant potential primary studies. The detailed data sources are explained in Table 1.

Table 1 Details of data sources
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Study selection

Inclusion criteria specified that studies must be: (1) in full-text, (2) published between years 2000 to 2017, and (3) primary articles focusing on palliative patients and their oral conditions.

Figure 1 illustrates Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow chart of study selection process [8]. The initial combined search identified 25,311 articles from 5 databases and from other sources (manual searching and through references). Removal of duplicates resulted in 13,263 studies. Screening of relevant abstracts resulted in 1230 studies. Further screening for inclusion criteria resulted in 67 studies which were read to ensure applicability to our study. This resulted in 28 articles being excluded. All reviewers screened and discussed preliminary findings to reach a consensus on studies to be included that resulted in total of 19 articles for further analysis.

Fig. 1
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Process of studies selection

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Data extraction

In the data extraction process [9], study details were extracted into a table (Table 1). This was done by two reviewers (Z.R., and D.R.). All reviewers discussed each article to reach consensus regarding the study details. For each included study, the following information was extracted: author(s), year published, title, purpose, setting, participants, study design, and oral conditions present. The impact, management and challenges of oral problems among palliative patients were also extracted and summarized according to our research questions.

Assessment of study quality

As our review included both qualitative and quantitative studies, we did not use any scoring for assessing the quality of studies included. Rather, the quality of the identified studies was assessed using Joanna Briggs Institute (JBI) critical appraisal tool [10]. As a result, only studies that were thoroughly appraised (have clearly defined inclusion criteria, study subjects and setting described in detail, exposure measured in a valid and reliable way, standard criteria used for measurement of condition, identification of confounding factors, outcomes measured in a valid and reliable way, and appropriate statistical analysis used) and agreed by all involved reviewers were included in this systematic review to write the findings.

Data analysis

Extracted data from all included studies were analyzed using the Whittemore and Knafl [9] principles of integrative review with four stages: data reduction, data display, data comparison, and conclusion and verification. At data reduction stage, all 19 primary sources included in the integrative review were divided into subgroups; initially based on types of study (qualitative and quantitative), sample (cancer patients, non-malignant palliative conditions and oral conditions among palliative patients) and then by a predetermined conceptual classification aligning with the aims of this review and then analyzed by topic. Each primary source was reduced to a single page (available on request from authors). This helped us to systematically compare primary sources on specific issues, variables and sample characteristics. It also allowed us to organize the data into a manageable framework. At stage 2 (data display), the single page data from the 19 included studies was extracted and displayed in the form of a table (see Table 1). This helped us to visualize the patterns and relationships between and within primary data sources. At stage 3 (data comparison), we used constant comparison as a method of an iterative process of examining data to identify themes that had similar patterns and relations. Finally at stage 4 (conclusion and verification), patterns using primary data were verified and any similarities, differences and any spurious findings were identified, in order to ensure that valuable information was not lost. Five consecutive meetings were held in order to identify and reach a consensus on the final themes.

Results

Characteristics of study

Overall, 19 articles were included in this review. The majority of the participants were cancer patients (n = 14). Studies reporting on oral conditions among palliative patients are summarized in Table 1. Of the included studies, 16 were quantitative studies [5, 11,12,13,14,15,16,17,18,19,20,21,22,23,24], and 3 were qualitative studies [25,26,27](Table 2).

Table 2 Summary of included studies
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Common oral conditions among palliative patients

Out of 19 studies, 13 reported xerostomia or dryness of mouth [5, 11, 14,15,16,17, 19, 23,24,25,26,27,28]. Eight studies reported candidiasis or oral thrush [11, 14, 16, 20, 23,24,25,26]. Six studies reported dysphagia or swallowing difficulties [15, 17,18,19, 22, 26]. Five reported mucositis [13,14,15, 21, 22] and 5 orofacial pain [5, 17, 22, 23, 28]. Four studies reported taste changes [5, 23, 25, 28] and two reported ulceration [5, 26], coughing [17, 18] and oral discomfort [25, 26].

Other oral conditions reported are stomatitis [11], salivary hypofunction [5], mucosal erythema [5], fungal infection [5], periodontitis [12], cold sores [14], dental caries [16], gingival inflammation [16], tongue coating and inflammation [16], bleeding spots [16], plaque [17], food particles and fungus infection [17], sores and scabs [17], viscous ropy saliva and chapped lips [17], halitosis [17], problems using dentures [17], problems with oral secretions [18], dysarthria [19], oral yeast carriage [24], mucosal friction [25], and bouts of ulceration and infection [27].

Multifaceted impact of oral conditions in palliative patients

Table 3 presents our findings associating the social and functional impact of oral conditions [5, 25,26,27,28]. Our review also revealed social and functional impact of having oral conditions among palliative patients. Social impact include feeling worried, bothered, a feeling of less satisfying life, shame, anxiety, depression, increased feelings of being a patient rather than a person, not wanting people to be around them which affected their social interaction and resulted in loneliness [5, 25,26,27,28]. Functional impact include difficulties in swallowing, speaking and eating, food restriction, sense of oral dryness and pain, which resulted in lack of food enjoyment [5, 26, 28].

Table 3 Studies addressing the impact of oral conditions among palliative patients
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Management of oral conditions among palliative patients

Table 4 presents our findings on the management of some oral conditions among palliative patients and their effectiveness [11, 15, 17, 19,20,21,22,23] Our study revealed that the common management options for xerostomia are drug and medical treatments [15], lubricating lips and mucosa [17], acupuncture [19], and standard oral care which improved dry mouth (in 80% or more) of the patients [11]. For candidiasis, a single-dose fluconazole 150 mg via mouth was found to be very effective as the symptoms decreased significantly (P < 0.001) in most patients [20], and local antifungal treatments were reported to be efficacious in 78.1% of the patients [23]. A substantial improvement of dysphagia was also observed after fifth treatment of acupuncture [19], however, its management using step-based pharmacological intervention and topically acting drugs caused worsening of swallowing and soreness of mouth [22]. Also, the management of mucositis using step-based pharmacological intervention and topically-acting drugs did not improve the oral condition [22], however, an indomethacin oral spray has been proven to relieve pain after 25 min [21].

Table 4 Studies addressing the management of oral conditions among palliative patients
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Treatment challenges of oral conditions in palliative patients

Table 5 presents our findings on the challenges in treating oral conditions among palliative patients [17, 18]. Only 2 of the included papers addressed the challenges in treating oral conditions among palliative patients. Kvalheim et al. (2016) found that some of the challenges were the lack of knowledge/routine, patient cooperation, resources, priority given to oral problems, as well as difficulty in accessing the mouth and retching. Bogaardt et al. (2015) observed underestimation of reported oral problems among palliative patients by rating significantly lower incidence and severity problems by the nursing staff compared to the patients’ relatives.

Table 5 Studies addressing the challenges in treating oral conditions among palliative patient
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Discussion

To our knowledge, this review is first of its kind to systematically and comprehensively synthesize the published evidence on oral conditions among palliative patients, impact, management and challenges in the management. Our review found that the most common oral conditions among palliative patients are xerostomia, oral candidiasis, dysphagia, mucositis, orofacial pain, taste change and ulceration. A previous study by Saini et al. (2009) has also stated xerostomia, oral candidiasis, mucositis, dysphagia, ulceration, taste disorders and pain as the most common oral problems among palliative patients [2]. Another discussion paper on oral cavity complications of patients with advanced cancer also found that xerostomia, oral candidiasis and taste alterations are very common among these patients which could lead to malnutrition and communication disorder [29]. In addition, Mulk et al. (2014) described the role of dentist in palliative team and categorized xerostomia and trouble in swallowing as the indication of terminal phase of life [30]. Chen (2015) proposed an oral health care model for seriously-ill old people and stated that xerostomia is a major problem in all dying stages (decline, pre-active dying and actively dying) which worsen with each stage due to kidney failure, dehydration, and the use of anticholinergic medications during the actively dying phase [31].

Our review also revealed social and functional impact of having certain oral conditions among palliative patients. In agreement, Saini et al. (2009) stated that oral lesions have an immense impact on the quality of life of patients with complex advanced diseases, causing considerable morbidity to patient’s physical condition due to reduced oral intake and weight loss, as well as psychological well-being due to impaired communication and feelings of exclusion and social isolation. Mulk et al. (2014) explained that the most common psychological problem for the elderly requiring a palliative approach is depression, and due to the lack of proper oral hygiene among depressed patients, they often present with halitosis (bad breath) which may cause people around them to stay away from them, causing severe social impact among these patients.

Our review also reported various treatment options for several oral conditions. For example, using salivary substitutes for xerostomia, and using fluconazole for candidiasis, and its effectiveness among palliative patients. Saini et al. (2009) also reported similar treatment options for some oral conditions as in the present study, they highlighted that one of the management option for dysphagia is to remove coating or plaque from teeth, and removal of dental prosthesis to clean and rectify for any technical error for mucositis, whilst emphasizing that the management of oral problems in palliative patients should be carried out as a team work and treatment protocol should be available to guide non-dentist and dental expert. On the other hand, a clinical paper on the management of oral mucositis in cancer patients found that the current clinical management of mucositis is largely focused on palliative measures such as pain management, nutritional support and maintenance of good oral hygiene, with several promising therapeutic agents in various stages of clinical development [32]. However, none of the studies mentioned complimentary therapies such as acupuncture as a treatment option neither for xerostomia and dysphagia nor any oral conditions among palliative patients.

Our review also highlights that the lack of knowledge among healthcare providers posed a challenge in treating oral conditions among palliative patients. A study reported that training and involvement of dental professionals in caring for palliative patients seem to remain limited [33]. On the other hand, evidence also report that patients and their families are less likely to prioritize oral care needs due to increased diseases burden, transportation difficulties and psychological distress at the end of life [4]. This study also found patient cooperation as a challenge in treating oral conditions among palliative patients as it was explained that is due to the process of transferring palliative patients to dental offices for oral examination and treatment that could be physically challenging and stressful for these patients.

Apart from the above, it can be seen that among the scientific articles included in the literature review, two papers are concerning head and neck cancer patients [21], which may be more significant on the patient’s oral well-being conditions, both for the localization of the tumor and the regional radiotherapy. Therefore, future reviews can focus on patients with specific types of cancer and their oral conditions. This would greatly contribute to the body of knowledge on palliative care. Regardless, our review has provided baseline knowledge that can guide health care professionals in palliative settings.

Conclusion

This review summarizes the diverse oral conditions that challenge the quality of life of palliative patients. Evidence is emerging on various treatment options for management of oral conditions among diverse palliative conditions. Our review also highlights the lack of evidence investigating palliative oral care among specific group of patients such as patients with dementia, geriatric or pediatric advanced cancer patients. Yet, this review provides baseline comprehensive knowledge and practice of quality oral care for palliative patients that may guide health care professionals in palliative settings.