Participants and procedures
In a cross-sectional study design, adult patients attending primary care health centres or monk healers were systematically recruited (consecutive sampling) after written informed consent was obtained. Purposeful sampling was used to select three monk healers or temples and three primary health care centres located in four districts of the eastern and central region of Thailand. Inclusion criteria for the selection of the study sites were to have at least five patients a day, and the inclusion criteria for the selection of clients or patients was aged 18 years and above. The study was conducted from November 2018 to February 2019. A professional nurse conducted face-to-face interviews in Thai language with patients on background data and CMD. Questionnaires were pretested for validity on a sample of 30 patients, not included in the final sample. Research nurses were systematically trained in the administration of the questionnaires. Moreover, the assessment procedures and implementation were routinely monitored by senior research staff. Study approval was obtained from each of the study sites, and the study protocol was approved by the “Office of The Committee for Research Ethics (Social Sciences), Mahidol University (No.: 2017/055.1403).”
Sociodemographic data included marital status, education, sex, age, work status, religion, and economic status (extent of debt).
Social support was assessed with the “Oslo 3-items Social Support Scale (OSSS-3)”, covering “the number of people the respondent feels close to, the interest and concern shown by others, and the ease of obtaining practical help from other.” . The total scores (3–14) were grouped into “3–8 = poor, 9–11, = moderate, and 12–16 strong support”  (Cronbach’s alpha 0.75 in this sample).
The Patient Health Questionnaire-9 (PHQ-9) was used to assess major depressive disorder (MDD)” . “It has demonstrated high sensitivity (0.84) and specificity (0.77) in a validation study in Thailand, using a cut-off score of nine or more as indicative for MDD”  (Cronbach’s alpha 0.88 in this sample).
The Generalized anxiety disorder 7-item (GAD-7) scale was used to measure “the severity of generalized anxiety, with a score of 10 or more indicating moderate or severe GAD”  (Cronbach’s alpha 0.92 in this sample).
The Patient Health Questionnaire-15 somatic symptoms (PHQ-15) screened for somatization disorder . “The somatic symptoms severity is calculated by assigning scores at 0, 1, and 2 to the response categories of not at all, bothered a little, and bothered a lot for the 15 somatic symptoms” . As recommended in previous research [20,21,22], cut-off scores ≥ 10 indicated moderate or high somatic symptom severity [20,21,22] (Cronbach’s alpha 0.83).
Descriptive statistics (frequencies, percentages, means, and standard deviations) is used to show the prevalence of CMD and sample characteristics. Differences in proportions were tested with Pearson chi-square tests and parametric tests. Univariate and multivariable logistic regression analyses were utilized to estimate demographic and social determinants of CMD by health care settings. The data were analysed with IBM-SPSS for Windows, version 25 (Chicago, IL, USA).