Psychiatry and Psychological Disorders

Abstract

One of the commonest mental health conditions managed in primary health care (PHC) is depression, with nearly 10% of all primary care consultations being related to depressive disorders. However, the detection of depression by PHC workers in developing countries remains markedly low. Routine screening for depression at the PHC level has the potential to improve the detection of depression. This study was undertaken to enhance the detection of depression through systematic screening in PHC settings in Ogun State, Nigeria.

Methodology

This study was conducted in 20 primary health care (PHC) centres across two randomly selected senatorial districts (Ogun West and Ogun Central) in Ogun State, Nigeria. The Patient Health Questionnaire-2 (PHQ-2) and the depression module of the Mental Health Gap Action Programme Intervention Guide (mhGAP-IG) were used to screen for depression among consenting patients who met the inclusion criteria in the designated PHC centres. A PHQ-9 score of ≥10 was used to confirm the diagnosis of depression. Data were analysed using the Statistical Package for the Social Sciences (SPSS) version 21.0. Descriptive statistics were summarised using frequencies, means, standard deviations, and percentages, while comparisons of quantitative variables were performed using the independent samples t-test. Statistical significance was set at p < 0.05.

Results

Out of the 493 patients screened for depression, 26.8% met the criteria for a diagnosis of depression. The mean depression score in Ogun West, where screening was conducted using the PHQ-2 and mhGAP-IG, was significantly higher (19.8) than that observed in Ogun Central (14.5) (p = 0.001). Most of the identified cases were of mild severity (50.8%). Females constituted the majority (62.3%) of the participants diagnosed with depression.

Conclusion

This study has demonstrated the synergistic screening effect of the PHQ-2 and mhGAP-IG manual in improving the detection of depression in primary health care settings in Ogun State, Nigeria. Strategies aimed at enhancing the recognition and management of depression, such as mental health training focused on depressive disorders and the routine screening of patients using these tools,should be incorporated into the routine service package at the primary health care level, as these measures are likely to improve the detection of depression.

Introduction

One of the major contributors to the global burden of disability is depression, and this constitutes a significant public health challenge. Within the healthcare system, primary care settings serve as the frontline for the management of depressive disorders, with General Practitioners (GPs) often representing the first point of clinical contact for most symptomatic individuals [1]. Empirical evidence indicates considerable variability in the prevalence of depression in general outpatient settings, with reported rates ranging from 11.4% to 59.6%. Notably, most of these cases are characterized by mild depressive symptomatology [2-3]. Despite the predominance of mild presentations in outpatient settings, the associated functional impairment remains substantial. Evidence suggests that even subthreshold or mild depressive states may result in significantly greater functional disability compared with non-depressed populations, with disability levels reported to be up to three times higher [4]. Furthermore, a growing body of literature has demonstrated significant associations between depressive disorders and various sociodemographic factors, many of which influence the onset, severity, and persistence of depression among outpatient populations [2-5-6]. Depression is recognized as one of the most common chronic conditions encountered in primary care; however, it frequently remains unrecognized [7]. One of the major challenges in diagnosing depression in these settings is the tendency for patients to present predominantly with somatic complaints rather than psychological symptoms, thereby complicating accurate diagnosis [8]. Such somatic presentations occur across diverse cultural contexts and contribute significantly to the under-recognition of depression in routine clinical practice [9]. There is substantial evidence indicating that the prevalence of depression is particularly high within primary healthcare settings [10-11]. A large multinational study involving participants from 14 countries reported that approximately 24% of individuals attending primary care facilities met the diagnostic criteria for depression [12], with similar findings reported in African populations [13]. Depression also constitutes a significant proportion of primary care consultations, with nearly 10% of visits associated with depressive symptoms, underscoring its considerable contribution to the workload of primary healthcare services [14]. Although most individuals with depression are managed within primary care settings [15], recognition rates remain subop-timal. Studies conducted in both high-income countries and low- and middle-income countries (LMICs) consistently report inadequate recognition of depression [16-17]. In high-income countries, more than half of depression cases remain undiagnosed [18], while detection rates are even lower in LMICs [13]. For instance, research conducted in rural Ethiopia demonstrated that over 95% of individuals with probable depression were neither identified nor provided with appro-priate treatment [19]. Although recognition alone does not guarantee treatment, it represents a crucial first step toward facilitating access to appropriate care [20]. Poor recognition rates also impede ongoing efforts to integrate mental health services into primary healthcare systems [19]. Addressing barriers to recognition among primary healthcare providers is therefore essential, particularly given evidence that effective treatment of depression improves health outcomes and is cost-effective [21]. This underscores the need for comprehensive and coordinated strategies aimed at improving the recognition and management of depression within primary care settings [22]. Several interventions have been developed to improve the recognition of depression by addressing system-level barriers, clinician competencies, and patient-related factors [18-21-23-24]. These interventions include routine screening, clinician training programmes, implementation of clinical guidelines, case management approaches, collaborative care models, and stepped-care interventions [25–28]. Evidence from previous studies, predominantly conducted in high-income countries, suggests that multifaceted and coordinated interventions, particularly those incorporating screening tools and chronic care models, are most effective in improving recognition rates in primary healthcare settings [29]. Systematic reviews further indicate that interventions combining clinician education, nurse-led case management, and enhanced collaboration with mental health specialists yield the most favourable outcomes [27]. Extensive research, including systematic reviews and meta-analyses, has evaluated the effectiveness of these interventions, particularly screening strategies, in improving the recognition of depression [21-23]. In Western countries, prevalence estimates of depression in primary care typically range from 15.3% to 22%, while studies conducted in Nigeria report prevalence rates ranging between 10% and 20% among primary care attendees [30–32]. Despite this significant burden, accurate diagnosis by non-specialist healthcare providers remains challenging in Nigeria. Evidence suggests that primary care physicians may fail to identify depressive symptoms in approximately 30% to 50% of affected individuals [33]. Nonetheless, task-shifting approaches have shown promise, with studies demonstrating that non-physician healthcare workers, including nurses and community health officers,can be effectively trained to provide psychosocial and pharmacological interventions for depression under specialist supervision [31-32-34]. In Ogun State, Nigeria, the Federal Neuropsychiatric Hospital, Aro, Abeokuta, has implemented mental health services within selected primary healthcare facilities over the past fifteen years. Training of primary healthcare workers was conducted using the World Health Organization’s Mental Health Gap Action Programme Intervention Guide (mhGAP-IG). However, findings from the Aro programme revealed persistent challenges in the recognition and management of depression, with relatively few cases identified by trained personnel [34]. Routine screening for depression in primary care settings has the potential to significantly improve recognition and reduce the adverse consequences associated with untreated illness. The introduction of brief and reliable screening instruments such as the Patient Health Questionnaire-2 (PHQ-2) and Patient Health Questionnaire-9 (PHQ-9) has facilitated this process. These instruments are easy to administer, time-efficient, and demonstrate good sensitivity and specificity in primary care settings [35]. Consequently, barriers such as limited consultation time and clinician discomfort in addressing emotional concerns can no longer sufficiently justify the failure to recognize depressive symptoms. In Ogun State, there is limited research examining the effectiveness of screening and recognition strategies for depression within primary healthcare settings. This study was therefore undertaken to improve the detection and management of depression through systematic screening based on the mhGAP-IG framework among patients attending primary healthcare facilities in Ogun State, Nigeria.

Methods

This study was conducted at Primary Health Care (PHC) centres across Ogun State, Nigeria. Ogun State is one of the 36 states in Nigeria and is divid-ed into three senatorial districts: Ogun Central, Ogun East, and Ogun West. Ogun Central consists predominantly of the Egba ethnic group and comprises six Local Government Ar-eas (LGAs): Abeokuta North, Abeokuta South, Ewekoro, Ifo, ObafemiOwode, and Odeda. Ogun West consists predomi-nantly of the Yewa ethnic group and comprises five LGAs: Ado-Odo/Ota, Imeko-Afon, Ipokia, Yewa North, and Yewa South. Ogun East senatorial district consists predominant-ly of the Ijebu and Remo ethnic groups and includes nine LGAs: Ijebu East, Ijebu North, Ijebu North-East, Ijebu Ode, Ikenne, Odogbolu, Ogun Waterside, Remo North, and Sag-amu. Ogun State has a population of over five million people and comprises twenty (20) LGAs, which are further grouped into four socio-political zones: Egba, Yewa, Remo, and Ijebu, with five LGAs in each zone. At the time of the study, there were 477 PHC centres across the state. Each LGA had a PHC director, who was a medical doctor, as well as an apex nurse responsible for coordinating PHC activities. In Ogun State, there were 1,225 non-physician PHC work-ers, comprising Nurses (60%), Community Health Officers (CHOs), and Community Health Extension Workers (CHEWs) (40%). All categories of health workers had received at least two years of post-secondary school education. The Neuropsychiatric Hospital, Aro, Abeokuta, which has specialist multidisciplinary mental health professionals, is the major mental health institution in Ogun State. The hospital provides mental health services to residents of Ogun State, other parts of Nigeria, and neighbouring countries. However, there are no specialist mental health professionals at the pri-mary healthcare level. In 2011, the Neuropsychiatric Hospital, Aro, entered into a collaborative agreement with the Ogun State Local Govern-ment Service Commission to provide mental health services and conduct mental health research at the primary care level [34]. As part of this collaboration, forty (40) PHC centres were se-lected and designated for the provision of mental health ser-vices and mental health research across the four socio-po-litical zones in Ogun State. Specifically, there were ten (10) PHC centres in each socio-political zone, comprising five urban and five rural centres across the Egba, Remo, Yewa, and Ijebu zones. The Aro community mental health team comprised a project coordinator, consultant psychiatrists, senior registrars in psy-chiatry, psychiatric nurses, social workers, pharmacists, psy-chologists, occupational therapists, administrative officers, drivers, and other support staff members. The study sites comprised 20 PHC centres located within Ogun Central (Egba zone) and Ogun West (Yewa zone). A total of 124 PHC workers, consisting of nurses and CHEWs, were trained using the adapted mhGAP-IG manual on five priority conditions: psychosis, depression, epilepsy, alcohol and substance use disorders, and anxiety disorders/other significant emotional complaints. The training was conducted by the Lead Community Consultant Psychiatrist and other mental health professionals. The training programme had previously been evaluated and found to be effective [34]. Of the 124 PHC workers trained, 72 were from Ogun Central, while 52 were from Ogun West senatorial district. As part of the training on the depression module, the PHC workers were also trained on the screening of depression using the PHQ-2 and PHQ-9 instruments. In addition, they were trained on the use of the depression module of the mh-GAP-IG guidelines for the screening and management of depression. The study employed a multicentre descriptive follow-up design and was conducted across 20 PHC centres within Ogun Central and Ogun West senatorial districts. The study population comprised patients who presented to the PHC centres for healthcare services, met the inclusion criteria, and provided informed consent to participate in the study. Sample size was estimated using Leslie-Kish formula for sin-gle Proportion Using the prevalence rate of depression ranging from 10-20% among primary care clinic attendees in Nigeria [32-36], then P= 0.2, and accounting for non-response based on a study on screening for mental disorder at the primary care setting in Lagos, which found the response rate to be 85.1% [38], a minimum sample size of 590 patients was used.

Study Instruments

Patient Health Questionnaire-2 (PHQ-2) (by self- adminis-tration) The PHQ-2 was used to screen for depression in a first-step approach. It is a questionnaire that scores each of the 2 questions from 0 to 3, with a total score ranging from 0 to 6. Scores of 3 and above are considered a positive screen for depression. The PHQ-2 has good psychometric properties, with a sensitivity of 83%, specificity of 92%, and positive predictive value of 80% for the diagnosis of major depression [35]. It has been used extensively in Nigeria, and the Yoruba-translated version [37] was used in this study for some patients who were not literate. It was used in the Yewa zone, in combination with the Mental Health Gap Action Programme Intervention Guide (mhGAP-IG).

Stage 2 (Making a Diagnosis of Depression)

The Patient Health Questionnaire-9 (PHQ-9) was used to establish the diagnosis of depression. All patients who had been assessed by the trained PHC workers during Stage 1 and screened positive for depression subsequently underwent further evaluation with the PHQ-9 administered by the field psychiatric nurses. The PHQ-9 is a brief and clinically useful instrument widely employed in routine clinical practice. It is typically completed by patients within approximately 10 minutes and can be rapidly scored by the researcher or clinician. The instrument serves as a multipurpose tool for the screening, diagnosis, monitoring, and assessment of the severity of depressive symptoms. The PHQ-9 comprises nine items, each scored on a four-point Likert scale ranging from 0 to 3, similar to the PHQ-2. Total scores range from 0 to 27. For interpretation of scores: 5 - 9 minimal symptoms 10 - 14 minor depression 15 - 19 moderate depression >20 severe depression For the diagnosis of depression, a PHQ-9 score of 10 or above was considered indicative of depression. A PHQ-9 cut-off score of ≥10 has been shown to have a sensitivity of 88% and specificity of 88% for major depressive disorder [35]. The PHQ-9 has been extensively used in Nigeria, and a validated Yoruba-translated version is available [37]. This translated version was administered to participants who were not literate in the English language.

mhGAP-IG Document

The Mental Health Gap Action Programme Intervention Guide (mhGAP-IG) is a tool developed by the World Health Organization (WHO) to assist non-specialist healthcare providers, including general practitioners, nurses, and community health workers, in the assessment and management of mental, neurological, and substance use (MNS) disorders, particularly in low- and middle-income countries (LMICs). The document was adapted to suit the local context in Ogun State, Nigeria [34]. The healthcare workers were trained on five priority conditions, including depression. The training covered screening procedures using the guidelines contained in the depression module of the mhGAP-IG, as well as the administration of the PHQ-2 and PHQ-9 instruments. It was utilised in both the Yewa and Egba zones.

Sociodemographic Questionnaire

A structured sociodemographic questionnaire was designed to obtain information on the participants’ sociodemographic characteristics. This section elicited information on sex, age, marital status, occupation, educational status, medical co-morbidity, duration of untreated mental illness, and types of medical conditions.

Sampling Procedure

The trained PHC workers and field psychiatric nurses participated in the screening of patients across the 20 PHC centres included in the study. At the clinic waiting areas, the study was explained to attendees in both English and Yoruba. Consecutive consenting attendees who met the inclusion criteria were recruited into the study.

Ethical approval

Ethical approval for the study was obtained from the Health Research Ethics Committee of the Federal Neuropsychiatric Hospital, Aro, Abeokuta, Ogun State (HREC/PR/004/19). Permission to conduct the study was also obtained from the Ogun State Local Government Service Commission (LGC.844/44). Written informed consent was obtained from all eligible and consenting participants. Participants were informed that participation was entirely voluntary and that they were free to withdraw from the study at any time without any penalty or loss of benefits.

Data Analysis

The completed proforma was checked for accuracy, serially coded, and entered into the database. Data cleaning and analysis were conducted using the Statistical Package for the Social Sciences (SPSS) version 21.0. Descriptive statistics, including frequencies, means, standard deviations, and percentages, were used to summarize the data. The Chi-square test was used to assess associations between qualitative variables, while the independent samples t-test was used to compare the means of quantitative variables. A p-value of less than 0.05 was considered statistically significant for all analyses.

Results

Out of a total of 590 patients who consented to participate in the study, 493 had fully completed study instruments and were therefore suitable for analysis. This represented 83.6% of the total number of patients screened. Among the 493 participants, 132 patients met the criteria for depression, yielding a prevalence rate of 26.8%. It is noteworthy that in Ogun West senatorial district (Yewa zone), 229 patients were screened, of whom 79 were diagnosed with depression, representing 34.5% of the screened population. In contrast, in the Ogun Central senatorial district (Egba zone), 264 patients were screened, with 53 patients diagnosed with depression, accounting for 20.1% of participants in that district. The sociodemographic characteristics of all participants are presented in Table 1. Among the 493 participants, 284 (57.6%) were between 20 and 40 years of age, while 169 (34.3%) were aged between 41 and 60 years. The mean age of the participants was 38.6 ± 2.0 years, indicating that the majority were within the economically productive age group. Females constituted 62.3% of the study population, suggesting a higher level of participation among female patients. Regarding educational attainment, 33.7% had primary education, 28.4% had secondary education, 18.5% had post-secondary education, and 9.1% had university education, while 9.9% had no formal education. With respect to marital status, 60.8% of the participants were married. In addition, 54.5% of the participants were unemployed. Regarding occupational classification, 50.9% of the participants were engaged in unskilled occupations.

Table 1: Socio-Demographic Variables of Patients Screened for Depression

Table 2a presents the findings on the screening of patients for depression across the two study zones using the PHQ-2 screening instrument. The total PHQ-2 score ranges from 0 to 6, with scores of 3 or above considered positive for depression screening. In the Yewa zone, a total of 229 patients were screened, of whom 88 (38.4%) screened positive for depression. The PHQ-9 was subsequently administered to these 88 patients, and 79 participants had scores of 10 or above. Initial screening in the Yewa zone was conducted using both the PHQ-2 and the depression module of the mhGAP-IG guidelines. Consequently, 79 (34.5%) of the 229 patients were confirmed to have depression. In the Egba zone, 264 patients were screened using only the mhGAP-IG depression module, of whom 60 (22.7%) screened positive for depression. The PHQ-9 was subsequently administered to these patients, and 53 had scores of 10 or above. Consequently, 53 (20.1%) of the 264 patients screened in the Egba zone were confirmed to have depression. Overall, a total of 132 (26.8%) participants from both zones met the criteria for a diagnosis of depression among the 493 patients who participated in the study.

Table 2a: Screening of patients and confirmation of Depression with PHQ-9

Table 2b shows that there was a significant difference in the detection rate of depression among trained PHC workers who routinely applied PHQ-2 (Yewa zone) for screening, compared to the Egba zone, which did not apply PHQ-2 to the patients. There was a higher detection of depression at the Yewa zone (34.5%) compared to the Egba zone (20.1%). There was a significant difference in the mean score of depression for the Yewa zone (19.8) (4.9) that used PHQ-2 + mhGAP-IG compared with the Egba zone (14.5) (3.8) that used only mhGAP documents (p=0.001).

Table 2b: Influence of combined PHQ-2 and mhGAP-IG on Depression Screening

The results presented in Table 3 summarise the sociodemographic characteristics of participants diagnosed with depression. The findings showed that 34.8% of the patients were males, while 65.2% were females. Regarding educational attainment, 29.0% had primary education, 26.7% had secondary education, and 13.0% had university education, while 13.0% had no formal education. With respect to marital status, 46.2% of the participants were married, whereas 34.6% were single. In terms of employment status, 54.3% were employed, while 44.1% were unemployed. Additionally, 43.2% of the participants were engaged in unskilled occupations. Slightly over 10% of the participants reported having comorbid physical health conditions, including hypertension, diabetes mellitus, and peptic ulcer disease.

Table 3: Demographic Characteristics of Patients Diagnosed with Depression

Discussion

In this study, the prevalence of depression obtained among patients attending primary healthcare settings in Ogun State was 26.8%. Previous studies on psychiatric morbidity at the primary care level have reported prevalence rates ranging from 21.3% to 63.1%, with depression consistently identified as the most common psychiatric condition encountered in these settings [32-38]. Studies conducted in primary care settings in Western countries have reported prevalence rates for depression ranging from 15.3% to 22% [30]. Similarly, studies conducted in primary care settings in Nigeria have shown that depression occurs in approximately 10–20% of patients attending clinics [31-32]. Among the 132 patients diagnosed with depression in the present study, the majority (50.8%) had mild depressive disorder. Although the prevalence obtained in this study is higher than the 20% reported by Gureje et al. [31], it is lower than the 48.7% reported by Obadeji et al. [37] in a study conducted in a primary healthcare facility in Ekiti State, Nigeria. Variations in the prevalence of depression reported across studies may be attributable to differences in study settings, methods of case ascertainment, and the sensitivity and specificity of the screening and diagnostic instruments employed. Among participants diagnosed with depression, the prevalence was approximately twice as high among females compared with males. This finding is consistent with the established epidemiology of depressive disorders [39]. More than half of the participants diagnosed with depression had secondary school education or lower educational attainment, while 34.6% were single, and nearly half were unemployed. These sociodemographic characteristics are similar to those reported in previous studies conducted in comparable settings [31-34-36-37]. Although attrition is often unavoidable in follow-up epidemiological studies, psychiatric research is particularly vulnerable to the effects of attrition, which may affect the validity and generalizability of findings [38]. One of the limitations of this study was the inability to control for factors such as physical comorbidities, which may have influenced the outcomes of the interventions. In addition, certain cultural, social, and economic factors that could potentially affect screening outcomes across the different senatorial districts were not controlled for. Future studies should seek to address these potential confounding variables.

Conclusion

This study has demonstrated the feasibility of improving the detection of depression in primary healthcare settings through the training of non-physician primary healthcare workers to use simple, easy-to-administer screening tools. Strategies aimed at improving the recognition and early intervention for depression, such as mental health training focused on depressive disorders and routine screening using the PHQ-2, PHQ-9, and mhGAP-IG tools,should be incorporated into routine service delivery at the primary healthcare level, as these measures are likely to improve the quality of mental health services for depression.

Conflict of Interest: None declared.

Acknowledgements

The authors acknowledge all members of the Aro Community and Primary Care Mental Health Programme, the trained PHC workers, all patients who participated in the study, the Ogun State Local Government Service Commission, and the management of the Federal Neuropsychiatric Hospital, Aro, Abeokuta, Nigeria.

References

1. Berardi, Domenico, Giuseppe Leggieri, Giuseppe Berti Cero-ni, Paola Rucci, Antonio Pezzoli, Elisabetta Paltrinieri, Natalia Grazian, and Giuseppe Ferrari. "Depression in primary care. A nationwide epidemiological survey." Family Practice 19, no. 4 (2002): 397-400.
   View at Publisher | View at Google Scholar
2. Afolabi,Muhammed O.,Emmanuel A. Abioye-Kuteyi,Femi O.Fatoye, Ibrahim S. Bello, and Abiodun O.Adewuya."Pattern of depression among patients in a Nigerian family practice popu-lation." South African Family Practice 50, no. 2 (2008):1.
   View at Publisher | View at Google Scholar
3. Baiyewu, Olusegun, Valerie Smith-Gamble, Kathleen A. Lane, Oye Gureje, Sujuan Gao, Adesola Ogunniyi, Frederick W. Un-verzagt, Kathleen S. Hall, and Hugh C. Hendrie. "Prevalence estimates of depression in elderly community-dwelling African Americans in Indianapolis and Yoruba in Ibadan, Nigeria." In-ternational psychogeriatrics 19, no. 4 (2007): 679-689.
   View at Publisher | View at Google Scholar
4. Hays, Ron D., Kenneth B. Wells, Cathy Donald Sherbourne, William Rogers, and Karen Spritzer. "Functioning and well-be-ing outcomes of patients with depression compared with chron-ic general medical illnesses." Archives of general psychiatry 52, no. 1 (1995): 11-19.
   View at Publisher | View at Google Scholar
5. Amoran, Olorunfemi, Taiwo Lawoyin, and Victor Lasebikan. "Prevalence of depression among adults in Oyo State, Nigeria: a comparative study of rural and urban communities." Austra-lian Journal of Rural Health 15, no. 3 (2007): 211-215.
   View at Publisher | View at Google Scholar
6. Qin, Xiaoxia, Wei Wang, Qiu Jin, Li Ai, Yueling Li, Guanghui Dong, Li Liu, and Michael R. Phillips. "Prevalence and rates of recognition of depressive disorders in internal medicine outpa-tient departments of 23 general hospitals in Shenyang, China." Journal of affective disorders 110, no. 1-2 (2008): 46-54.
   View at Publisher | View at Google Scholar
7. Sharp, Lisa K., and Martin S. Lipsky. "Screening for depression across the lifespan: a review of measures for use in prima-ry care settings." American family physician 66, no. 6 (2002): 1001-1009.
   View at Publisher | View at Google Scholar
8. Suh, Tongwoo, and Joseph J. Gallo. "Symptom profiles of de-pression among general medical service users compared with speciality mental health service users." Psychological medi-cine 27, no. 5 (1997): 1051-1063.
   View at Publisher | View at Google Scholar
9. Okulate, G. T., M. O. Olayinka, and O. B. E. Jones. "Somatic symptoms in depression: evaluation of their diagnostic weight in an African setting." The British Journal of Psychiatry 184, no. 5 (2004): 422-427.
   View at Publisher | View at Google Scholar
10. Tylee, André, and Paul Gandhi. "The importance of somatic symptoms in depression in primary care." Primary care com-panion to the Journal of clinical psychiatry 7, no. 4 (2005): 167.
    View at Publisher | View at Google Scholar
11. Katon, Wayne, and Herbert Schulberg. "Epidemiology of de-pression in primary care." General hospital psychiatry 14, no. 4 (1992): 237-247.
    View at Publisher | View at Google Scholar
12. Üstün, T. Bedirhan, and Norman Sartorius, eds. Mental illness in general health care: an international study. John Wiley & Sons, 1995.
    View at Publisher | View at Google Scholar
13. Udedi, Michael. "The prevalence of depression among patients and its detection by primary health care workers at Matawale Health Centre (Zomba)." Malawi Medical Journal 26, no. 2 (2014): 34-37.
    View at Publisher | View at Google Scholar
14. Zung, William W. "The role of rating scales in the identification and management of the depressed patient in the primary care setting." The Journal of clinical psychiatry 51 (1990): 72-76.
    View at Publisher | View at Google Scholar
15. Coyne, James C., Suzanne Fechner-Bates, and Thomas L. Schwenk. "Prevalence, nature, and comorbidity of depressive disorders in primary care." General hospital psychiatry 16, no. 4 (1994): 267-276.
    View at Publisher | View at Google Scholar
16. Egede, Leonard E. "Failure to recognize depression in primary care: issues and challenges." Journal of General Internal Med-icine 22, no. 5 (2007): 701-703.
    View at Publisher | View at Google Scholar
17. Craven, Marilyn A., and Roger Bland. "Depression in primary care: current and future challenges." The Canadian Journal of Psychiatry 58, no. 8 (2013): 442-448.
    View at Publisher | View at Google Scholar
18. Gilbody, Simon, Trevor Sheldon, and Allan House. "Screening and case-finding instruments for depression: a meta-analysis." Cmaj 178, no. 8 (2008): 997-1003.
    View at Publisher | View at Google Scholar
19. Fekadu, Abebaw, Girmay Medhin, Medhin Selamu, Tedla W. Giorgis, Crick Lund, Atalay Alem, Martin Prince, and Charlotte Hanlon. "Recognition of depression by primary care clinicians in rural Ethiopia." BMC family practice 18, no. 1 (2017): 56.
    View at Publisher | View at Google Scholar
20. Haavet, Ole Rikard, Manjit Kaur Sirpal, Wenche Haugen, and Kaj Sparle Christensen. "Diagnosis of depressed young people in primary health care—a validation of HSCL-10." Family prac-tice 28, no. 2 (2011): 233-237.
    View at Publisher | View at Google Scholar
21. Gilbody, S., P. Whitty, J. Grimshaw, and R. Thomas. "Improving the detection and management of depression in primary care." Quality & safety in health care 12, no. 2 (2003): 149.
    View at Publisher | View at Google Scholar
22. Ng, Chung Wai Mark, Choon How How, and Yin Ping Ng. "Ma-jor depression in primary care: making the diagnosis." Singa-pore medical journal 57, no. 11 (2016): 591.
    View at Publisher | View at Google Scholar
23. O'Connor, Elizabeth A., Evelyn P. Whitlock, Tracy L. Beil, and Bradley N. Gaynes. "Screening for depression in adult patients in primary care settings: a systematic evidence review." Annals of internal medicine 151, no. 11 (2009): 793-803.
    View at Publisher | View at Google Scholar
24. Gilbody, Simon. "What is the evidence on effectiveness of capacity building of primary health care professionals in the detection, management and outcome of depression?." (2004).
    View at Publisher | View at Google Scholar
25. Zuckerbrot, Rachel A., and Peter S. Jensen. "Improving recog-nition of adolescent depression in primary care." Archives of pediatrics & adolescent medicine 160, no. 7 (2006): 694-704.
    View at Publisher | View at Google Scholar
26. Thompson, C., A. L. Kinmonth, L. Stevens, R. C. Pevele, A. Stevens, K. J. Ostler, R. M. Pickering et al. "Effects of a clini-cal-practice guideline and practice-based education on detec-tion and outcome of depression in primary care: Hampshire Depression Project randomised controlled trial." The Lancet 355, no. 9199 (2000): 185-191.
    View at Publisher | View at Google Scholar
27. Unützer J, Park M. Strategies to improve management of de-pression in primary care. Prim Care. 2012; 39:415–431.
    View at Publisher | View at Google Scholar
28. Nease Jr, Donald E., Paul A. Nutting, Deborah G. Graham, W. Perry Dickinson, Kaia M. Gallagher, and Michelle Jeffcott-Pera. "Sustainability of depression care improvements: success of a practice change improvement collaborative." The Journal of the American Board of Family Medicine 23, no. 5 (2010): 598- 605.
    View at Publisher | View at Google Scholar
29. Asarnow, Joan Rosenbaum, Lisa H. Jaycox, Naihua Duan, Anne P. LaBorde, Margaret M. Rea, Pamela Murray, Martin Anderson, Christopher Landon, Lingqi Tang, and Kenneth B. Wells. "Effectiveness of a quality improvement intervention for adolescent depression in primary care clinics: a randomized controlled trial." Jama 293, no. 3 (2005): 311-319.
    View at Publisher | View at Google Scholar
30. Ballou S, Katon J, Singh P, Rangan V, Lee HN, et al. Depres-sion and gastrointestinal symptoms. Clin Gastroenterol Hepa-tol. 2019; 17:2696–2703.
    View at Publisher | View at Google Scholar
31. Gureje, Oye, Jibril Abdulmalik, Lola Kola, Emmanuel Musa, Mohammad Taghi Yasamy, and Kazeem Adebayo. "Integrating mental health into primary care in Nigeria: report of a demon-stration project using the mental health gap action programme intervention guide." BMC health services research 15, no. 1 (2015): 242.
    View at Publisher | View at Google Scholar
32. Ndukuba, A. C., P. C. Odinka, R. C. Muomah, and S. O. Nwo-ha. "Clinical and socio-demographic profile of women with post-partum psychiatric conditions at a federal neuropsychiat-ric hospital in southeast Nigeria between 2009 and 2011." An-nals of medical and health sciences research 5, no. 3 (2015): 168.
    View at Publisher | View at Google Scholar
33. Garcia, Maria E., Ladson Hinton, Steven E. Gregorich, Jenni-fer Livaudais-Toman, Celia P. Kaplan, Mitchell Feldman, and Leah Karliner. "Primary care physician recognition and docu-mentation of depressive symptoms among Chinese and Latinx patients during routine visits: a cross-sectional study." Health Equity 5, no. 1 (2021): heq-2020.
    View at Publisher | View at Google Scholar
34. Adebowale, Timothy, Onofa Lucky Umukoro, Richard Gater, Akin Akinhanmi, Adegboyega Ogunlesi, Cleone Helme, Gra-ham Wood, and Imisioluwa Ibikunle. "Evaluation of a mental health training course for primary health care workers in Ogun State, South West, Nigeria." Afr J Psychiatry 17, no. 5 (2014).
    View at Publisher | View at Google Scholar
35. Mitchell, Alex J., Motahare Yadegarfar, John Gill, and Brendon Stubbs. "Case finding and screening clinical utility of the Pa-tient Health Questionnaire (PHQ-9 and PHQ-2) for depression in primary care: a diagnostic meta-analysis of 40 studies." BJ-Psych open 2, no. 2 (2016): 127-138.
    View at Publisher | View at Google Scholar
36. Gureje O, Bibiola O, Richard A, Alan MA (2015) ClusterRan-domizedClinicalTrialofaSteppedCareInterventionforDepres-sioninPrimaryCare (STEPCARE) StudyProtocol. BMCPsychi-atry 15: 148.
    View at Publisher | View at Google Scholar
37. Obadeji, Adetunji, Lateef Olutoyin Oluwole, Mobolaji Usman Dada, Adedotun Samuel Ajiboye, Banji Frenado Kumolalo, and Olusoji A. Solomon. "Assessment of depression in a pri-mary care setting in Nigeria using the PHQ-9." Journal of family medicine and primary care 4, no. 1 (2015): 30-34.
    View at Publisher | View at Google Scholar
38. Lasebikan, V. O., A. Ejidokun, and O. A. Coker. "Prevalence of mental disorders and profile of disablement among primary health care service users in Lagos Island." Epidemiology Re-
    View at Publisher | View at Google Scholar
39. Evans-Lacko, S. A. G. S., Sergio Aguilar-Gaxiola, Ali Al-Hamza-wi, Jordi Alonso, Corina Benjet, Ronny Bruffaerts, Wai-Tat Chiu et al. "Socio-economic variations in the mental health treat-ment gap for people with anxiety, mood, and substance use disorders: results from the WHO World Mental Health (WMH) surveys." Psychological medicine 48, no. 9 (2018): 1560-1571.
    View at Publisher | View at Google Scholar