Introduction

Posttraumatic stress disorder (PTSD) is a prevalent disorder throughout the world, and is associated with significant morbidity [1, 2]. PTSD leads to individual suffering, reduced quality of life, and considerable societal costs [3, 4]. Fortunately, there is a growing evidence-base of efficacious treatments for this condition, including various forms of psychotherapy and pharmacotherapy [5, 6]. Treatment guidelines for PTSD have been developed by several professional organizations to encourage evidence-based interventions, with most guidelines advocating both pharmacotherapy and psychotherapy as first-line interventions [7, 8]. Data from the WHO World Mental Health Surveys have emphasized that the delay in treatment seeking for mental disorders is a global problem [9], and that there is a treatment gap for a range of these conditions, including anxiety disorders and PTSD [10].

Although contact coverage (the percentage of people in need that get any service) is an important indicator, effective coverage (the percentage that get good care and obtain health benefits) is particularly relevant to health system performance assessment [11, 12]. Determining the extent and predictors of effective coverage for PTSD is an important first step towards developing appropriate strategies to address obstacles to care. While some structural and attitudinal barriers have received attention [13], a number of others, including symptom severity and health insurance have not. The focus on universal health coverage in the Sustainable Developmental Goals further emphasizes the need to investigate effective coverage [14]. A small literature on effective coverage indicators in the area of mental health has emerged, and relies on a number of different methods including need assessment strategies, utilization assessment strategies, and quality assessment strategies [12, 15]. The recent development of an “effective treatment coverage” indicator that quantifies utilization, but also adjusts for quality of care and user adherence, facilitates such work [16].

The WHO World Mental Health Survey Initiative provides a valuable dataset for more detailed investigations of effective treatment coverage across the world, so providing an important foundation for work on addressing key barriers to care and scaling up interventions [16, 17]. We investigated the extent and predictors of treatment coverage for PTSD in individuals who met DSM-IV criteria for 12-month PTSD in a range of high-income countries (HICs) as well as low- and middle-income countries (LMICs). Components of treatment coverage analyzed were: (a) any mental health service utilization; (b) adequate pharmacotherapy; (c) adequate psychotherapy; and (d) effective treatment coverage (adequate severity-specific use of pharmacotherapy and/or psychotherapy).

Methods

Sample

The WHO World Mental Health Surveys (WMHS) include 17 community surveys with 35,012 adults across 15 countries, including six classified by the World Bank as low- or middle-income countries (LMICs) and nine classified as high-income countries (HICs) [18]. All samples were based on multi-stage clustered area probability household designs. Samples were nationally representative in 11 surveys, representative of all urbanized areas in two others, and representative of selected regions or Metropolitan areas in the others [18] (Table 1).

Table 1 WMH sample characteristics by World Bank income categoriesaCountry
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Surveys were approved by the review boards of the coordinating organizations, which monitored adherence with procedures for informed consent [19]. Interviews were carried out face-to-face in respondents’ homes by trained lay interviewers. Field training and quality control procedures are described elsewhere [19]. Respondents were aged 18+ in all surveys other than one (19+ in Medellin, Colombia) and had unrestricted upper age limits in most surveys. The average response rate weighted by sample size was 70.3% using the American Association for Public Opinion Research RR1w definition [20].

To reduce respondent burden, interviews were divided into two parts [21]. Part I, administered to all respondents, assessed core mental disorders. Part II assessed additional disorders and correlates and was administered to all respondents with any Part I disorder plus a probability subsample of other Part I respondents. Part II data were weighted to adjust for the under-sampling of Part I non-cases [21]. In total, 71,576 Part I and 35,012 Part II respondents were interviewed. Of these 35,012 respondents, 914 met DSM-IV criteria for 12-month PTSD (Table 2).

Table 2 Sociodemographic distribution of the sample by country-income level, among those with 12-month posttraumatic stress disorder
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Measures and data analysis

The interview schedule used in WMH was the WHO Composite International Diagnostic Interview (CIDI) Version 3.0 [22], a fully-structured interview generating lifetime and 12-month prevalence estimates of common DSM-IV disorders that includes stringent protocols of translation, back-translation, expert review, adaptation, and harmonization across sites [23]. Blinded clinical reappraisal interviews with the Structured Clinical Interview for DSM-IV had good concordance with diagnoses based on the CIDI [24]. Respondents with PTSD were considered severe either if their symptoms resulted in severe role impairment (7–10 points) according to the Sheehan Disability Scale [25], moderate if they reported moderate role impairment in the SDS (4–6), and mild if they reported no or moderate role impairment (3 or less).

We classified health treatment providers into two categories: (1) specialist mental health (SMH; psychiatrist, psychologist, other mental health professional in any setting, social worker or counselor in a mental health specialized setting); and (2) general medical (GM; primary care doctor, other medical doctor, any other healthcare professional seen in a GM setting) [18]. Respondents were asked about number of visits with each type of provider in the past 12 months and, for medical providers, about whether they provided psychotherapy, pharmacotherapy, or both. Specific type, dose, and duration were recorded for each psychotropic medication used in the past 12 months. Further details about the treatment variables are presented elsewhere [26].

Consistent with our previous work [18], a series of summary variables was created from these detailed respondent reports. Contact coverage involved any 12-month contact with a specialist or general medical provider for a mental health condition. For the pharmacotherapy measures two clinical psychiatrists with expertise in public health (DV, CSW) independently reviewed responses about medications used (which involved selecting from country specific lists including generic and brand names) and classified them. Discrepancies were reconciled by consensus.

As described in our previous work [18], Adequate medication control required at least four physician visits [26]. Medication adherence required taking the prescribed daily dose at least 90% of the time during the past 12 months of pharmacotherapy (e.g., at least 27 out 30 days in a month) [27,28,29]. Adequate pharmacotherapy required taking an antidepressant with adequate medication control and adherence. While some PTSD guidelines have recommended only specific antidepressants, others have made broader recommendations [7]. A small fraction of people with PTSD may avoid antidepressants due to side effects, failed trials, or other legitimate reasons, so if a non-antidepressant psychotropic was adequately controlled by a psychiatrist with adequate patient adherence, it was also considered adequate.

In congruence with our previous work [30], Any psychotherapy required having two or more visits to any specialty mental health provider among help seekers. Adequate number of sessions required at least eight sessions. Adequate psychotherapy required at least 8 sessions from an adequate provider or still being in treatment after 2 visits. In the case of psychiatrists, for an encounter to be considered as a psychotherapeutic intervention (as opposed to medication adjustment), visits needed to last 30 minutes or more. PTSD guidelines emphasize the efficacy of trauma-focused therapies, but some make more specific recommendations, while others recommend broader classes of psychotherapy [7]. We chose “at least 8 sessions” following the United Kingdom’s National Institute for Health and Care Excellence (NICE) guidelines for the psychotherapy of PTSD [31]; this also has the advantage of mirroring definitions used in previous WMHS research on effective treatment coverage for MDD [18].

We also defined a severity-specific variable for effective treatment coverage, which for mild and moderate PTSD required adequate pharmacotherapy and/or adequate psychotherapy, and for severe PTSD both adequate pharmacotherapy and adequate psychotherapy [26, 32]. These criteria are consistent with our previous work on depression. However, the evidence-base on combined treatment for PTSD is thin, and most PTSD guidelines do not recommend initiating treatment with combined pharmacotherapy and psychotherapy [33]. Nevertheless, there is a clinical rationale for considering combined treatment in some patients, and the combination of evidence-based pharmacotherapy and psychotherapy has been recommended when initial treatments fail [34].

The sample for analysis was respondents who met criteria for 12-month PTSD. Differences in within-household probabilities of selection and residual discrepancies between sample and population distributions were adjusted for through weights based on census demographic-geographic variables [21]. The Taylor series linearization method [35] implemented in SUDAAN software [36] was used to estimate standard errors to adjust for weighting and geographic clustering of data. Components of effective treatment coverage were stratified by country-income level.

As described in our previous work [30], bivariate logistic regression analyses were employed to explore significant associations between a broad set of potential predictors (gender, age, marital status, income, education, type of health insurance, private insurance (yes/no), any form of insurance (yes/no), employment status, severity, and survey year) and the outcome of interest, effective treatment coverage for PTSD. A multivariable logistic regression model was employed to predict effective treatment coverage including all the variables that had p < .01 in the bivariate analyses. Significance was established at p < 0.05, and we report the unadjusted p values as well as values adjusted for false discovery rates (FDR) resulting from multiple testing using the Benjamini-Hochberg procedure.

Additionally, as detailed in previous articles in this series [18], for those bivariate models that were significant in predicting effective treatment coverage, we conducted exploratory analyses by decomposing this indicator to identify which components may drive coverage for specific subgroups. Thus, we investigated determinants of contact coverage among those with 12-month PTSD, and of the specific components of treatment (i.e., any pharmacotherapy, adequate pharmacotherapy, any psychotherapy, and adequate psychotherapy) among those with 12-month PTSD and contact coverage. Finally, we stratified the bivariate and multivariable analyses by country-income level.

Results

Effective treatment coverage

Twelve-month PTSD prevalence in trauma exposed individuals was 1.49% (S.E., 0.08) across countries. A total of 43.0% (S.E., 2.2) of these cases had contact coverage. Among these individuals with contact coverage (a) 32.7% (S.E., 1.9) received pharmacotherapy, but fewer received antidepressants (22.1% [S.E., 1.6]), and only 13.5% (S.E., 1.4) received adequate pharmacotherapy; (b) 19.9% (S.E., 1.5) received psychotherapy and slightly less (17.2% [S.E., 1.5]) received adequate psychotherapy; (c) 14.4% (S.E., 1.4) received effective treatment coverage (Table 3).

Table 3 Coverage for posttraumatic stress disorder by severity
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Stratification by country income-level (HIC vs LMIC) demonstrated that (a) contact coverage (50.6% vs 19.8%; (b) adequate pharmacotherapy (16.6% vs 4.1%); (c) adequate psychotherapy (21.3% vs 4.5%; and (d) effective treatment coverage (17.8% vs 4.1%) were all higher in HICs than in LMICs (Fig. 1).

Fig. 1
figure 1

Treatment coverage for posttraumatic stress disorder (12-month PTSD). HICs (n = 694): High income countries; LMICs (n = 220): Low/ middle income countries. Contact coverage required any 12-month contact with a specialist or general medical provider for a mental health condition. Any psychotropic required receiving any psychotropic and any 12-month healthcare. Antidepressants required appropriate medication (antidepressant) and any 12-month healthcare. Adequate medication control required at least four physician visits. Adequate pharmacotherapy required taking an antidepressant with adequate medication control and adherence. Any psychotherapy required having two or more visits to any specialty mental health provider among help seekers. Adequate psychotherapy required at least 8 sessions from an adequate provider or still being in treatment after 2 visits. Effective treatment coverage, for mild and moderate PTSD required adequate pharmacotherapy and/or adequate psychotherapy, and for severe PSTD both adequate pharmacotherapy and adequate psychotherapy

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Predictors of effective treatment coverage

In initial bivariate models, level of education, type of insurance, and severity of symptoms were associated with effective treatment coverage (Table 4). Those with low-average and average-high levels of education were less likely to receive effective treatment than those with high level of education. In general, those with any form of insurance are more likely to receive effective treatment coverage than those with no insurance. Having state funded coverage or subsidized insurance made it more likely to receive any modality of therapy and effective treatment, while those with insurance through employment or national social security were more likely to receive any pharmacotherapy, adequate pharmacotherapy, or effective treatment. Those with mild or moderate symptoms were less likely to receive any or adequate pharmacotherapy, or any or adequate psychotherapy, and those with mild symptoms were less likely to receive effective treatment. Stratification by country-income level showed similar findings in HICs (Supplemental Tables S1 and S2), while in LMICs the sample size did not allow for analyses by effective treatment and its components, analyses of contact coverage found that any form of insurance was particularly important in predicting contact coverage (Supplement Table S3).

Table 4 Bivariate predictors of effective coverage and its components among those with 12-Month posttraumatic stress disorder, in all countries (n = 914)a
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In the final multivariable model, after adjusting for the FDR, any form of insurance (OR = 2.31, 95% CI 1.17, 4.57) and mild symptom severity (OR = .35, 95% CI 53,1.08) remained significant predictors (Table 5). Stratification by country-income level showed similar findings in HICs (Supplement Table S2), while in LMICs although sample size again did not allow analyses by effective treatment and its components any form of insurance was again particularly important in predicting contact coverage (Supplement Table S3).

Table 5 Multivariable model of effective coverage among those with 12-Month posttraumatic stress disorder, in all countries (n = 914) a
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Discussion

Key findings from this analysis of WHO World Mental Health Surveys (WMHS) data were 1) that only 43.0.% of those with 12-month PTSD had contact coverage, with fewer receiving adequate pharmacotherapy (13.5%), adequate psychotherapy (17.2%), or effective treatment coverage (adequate severity specific use of pharmacotherapy and/or psychotherapy) (14.4%), and with all components of treatment coverage lower in LMICs than HICs, and 2) that lack of insurance and mild clinical symptoms were predictive of lower effective treatment coverage for PTSD.

The literature on treatment coverage of PTSD is relatively sparse. In veterans in the United States, studies have found that 23–40% of those who screened positive for a mental health issue received professional assistance [37], that 53% of those recently diagnosed with PTSD in primary care started treatment at that level [38], and that only 33% of veterans have received minimally adequate PTSD care [39]. In earlier work from the WMHS, of those with a 12-month anxiety disorder or PTSD, only 41.3% perceived a need for care, and only 27.6% received any treatment [10].

Several barriers to treatment of PTSD have previously been reported in the literature. These include both structural barriers such as lack of those providing evidence-based psychotherapy for PTSD [40], and attitudinal barriers such as ambivalence about treatment seeking [41]. In veterans in the US, those recently diagnosed with and treated at primary care level are more likely to receive pharmacotherapy [42]. In earlier work from the WMHS on barriers to care, low perceived need was the most common reason for not initiating treatment and was more common among moderate and mild than severe cases. Notably, attitudinal barriers dominated for mild-moderate cases, while structural barriers were more important for severe cases [13].

The finding that patients with more severe symptoms are more likely to receive effective treatment coverage suggests that a more comprehensive treatment package is available for people who suffer severe PTSD, compared to those that suffer severe MDD [18]. While more severe PTSD symptoms may be associated with more disability, previous findings from WMHS have emphasized the graded relationship between PTSD severity and clinical outcomes [43]. Thus decisions about treating cases should be based on cost-effectiveness rather than severity [44]. There is growing evidence of the cost-effectiveness of interventions for individuals meeting diagnostic criteria for PTSD, although further such work is needed [4].

The most important social determinant of treatment coverage was the presence of insurance. Private insurance was also found to be a significant predictor in our previous work on effective treatment coverage for major depressive disorder, but in this case the difference is more salient: every form of insurance warrants increased coverage for PTSD when compared to no insurance [18]. A focus on the relevance of insurance for treatment coverage is timely given the current emphasis on universal health care coverage [14, 45].

Some limitations deserve emphasis. First, the data regarding service utilization and adherence are dependent on respondent recall. However, the focus here on 12-month treatment rather than lifetime prevalence minimizes recall bias. To compensate for potential bias we used a particularly stringent compliance threshold (taking the indicated dose at least 90% of the time) [27,28,29]. With respect to the time-span covered by surveys, our models included dummy control variables for each survey, an approach that controls for survey year, so that findings are based on pooled within-survey results. Second, several aspects of the treatment provided, such as adherence to treatment manuals, may influence judgments of whether or not treatment coverage was effective. While a clinical trial allows assessment of such issues, it does not have the statistical power of an epidemiological approach. Third, our definitions of adequate treatment mirror our prior work on depression, but the evidence-base of randomized controlled trials of interventions for PTSD is smaller, with fewer approved pharmacotherapies, fewer evidence-based psychotherapies, and less evidence for the value of combined pharmacotherapy and psychotherapy [33]. Although our definitions of adequate treatment overlap in part with evidence-based guidelines for PTSD such as the NICE guideline their limitations deserve emphasis; for example, although such treatment guidelines for PTSD note the value of both pharmacotherapy and psychotherapy, they emphasize initiating treatment with either specific antidepressants or psychotherapies, rather than their combination.

In summary, these data emphasize that there is a clear need to improve pharmacotherapy and psychotherapy coverage for PTSD, particularly in those with mild symptoms, and especially in LMIC contexts. Previous work has emphasized the potential value of increasing human resources for mental health care and of increasing population mental health literacy in order to address structural and attitudinal barriers to accessing mental health services [14]. A key component of addressing such barriers is the provision of universal health care insurance for both physical and mental disorders.