Screening programs are the key element to monitor and achieve mental health Andrade et al., 2002Blum and Nelson-Mmari, 2004. Caring of people with mental disorders can help improve their well-being Jason B. Luoma et al., 2002. It is estimated that in 2030 mental disorders will become the second leading cause of burden of disease worldwide; thus, the disability-adjusted life years (DALYs) associated with mental disorders is expected to increase. Among mental disorders, depression and anxiety are more the two most prevalent Nock et al., 2010. For mental disorders, co-morbidity is a prognostic factor for some outcomes, according to previous findings Veisani et al., 2017. Indeed, 90% of people who die from suicide have had a diagnosable mental disorder Halvorsen et al., 2011. The prevalence of mental disorders varies in populations due to differences in sampling methods, interview techniques, employed tools and diagnostic classifications Veisani et al., 2017.

Three nationwide studies have been done to estimate the prevalence of mental disorders in Iran in the last decade. Noorbala et al., in 1999, enrolled 35,014 participants in his study; it was reported that the prevalence rate of mental disorders was 20.1%; the lowest prevalence was reported in the Yazd province (1.7%) and the highest prevalence was seen in the Chaharmahal and Bahkhtiari provinces (38.9%) Noorbala A.A and S., 2015. In two other studies, conducted by Mohammadi et al. in 2001 and Rahimi et al. in 2011, the prevalence rates of mental disorders were reported as 17.1% and 23.6%, respectively Mohammadi et al., 2005Rahimi-Movaghar et al., 2014. The reason for the high prevalence was unclear. However, some significant factors included gender (higher prevalence in females) and urban living Mohammadi et al., 2003Noorbala et al., 2004.

The Ilam province (where the present study took place) has one of the highest rates of depression and suicide among the 31 provinces in Iran Taherifard et al., 2013Veisani et al., 2016. In this study, the aim was to determine the efficacy of diagnosis of psychiatric and mental disorders (based on GHQ questionnaire and DSM-IV-TR classification) and if there were any gender differences.

In this cross-sectional study, 763 persons (of ages 15 years and above) were screened; for all participants the GHQ-28 questionnaire was advised for evaluation. The Mean±SD age of respondents was 37.90±14.2, with a range from 15 to 88 years ( Table 1 ). The majority of participants were females (423; 55.4%), in the 26-45 age group (373; 48.9%), married persons (579; 75.9%), and unemployed (461; 60.4%). According to educational level, 11.0% were literates, 12.5% were in elementary level, 14.4% were in secondary school, 29.0% had diplomas, and 33.2 had above diploma education.

Our results showed that the prevalence of psychiatric disorders in females was significantly greater than in males (p<0.003) ( Table 1 ). As well, married subjects had a significantly higher prevalence rate of psychiatric disorders when compared with singles (p<0.035). The prevalence of psychiatric disorders was associated significantly with unemployment status of the subjects (p<0.001). For educational background, the prevalence of psychiatric disorders showed differing patterns among the various educational levels of the subjects ( Table 1 ).

The mean score of the GHQ-28 in all respondents for the 28 items was 0.98±0.34 (Min 0.25, Max 2.54). The mean score of the items in suspected persons was 1.41, and in non-suspected persons was 0.75. The frequency and mean score of the items by gender are shown in Table 2 . Overall, 25.8% of responders had a cutoff score of 23 that demonstrated they displayed suspected psychological distress and needed to be further evaluated.

In this study, according to traditional scoring of the Persian GHQ-28 version, we used a cut-off score of 23 to determine suspected patients. The aforementioned cut-off in the ROC corresponded to area under ROC curve of 0.9173 (sensitivity of 91.0% and specificity of 51%) with respect to second evaluation by DSM-IV-TR for mental disorders ( Figure 1 ).

The suspected cases on sub-scales of GHQ-28 by gender are shown in Table 3 . According to the table, 21.4% of all responders were suspected of somatization (26.2% of females; 15.3% of males) (p<0.001), 20.1% were suspected of anxiety (21.0% of females; 18.8% of males) (p=0.252), 30.3% were suspected of social dysfunction (28.1% of females; 32.9.50% of males) (p=0.087), and 24.8% were suspected of severe depression (24.6% of females; 25.0% of males) (p=0.481).

Table 4 shows the prevalence rates of DSM-IV-TR mental disorders by gender. According to the table, in males the most prevalent mental disorders were: anxiety disorder (18.2%), any major depressive disorder (MDD) (17.4. %), compulsive disorder (10.0%), and phobia disorder (5.0%). In females, the most prevalent mental disorders were: anxiety disorder (23.6%), MDD (22.7%), compulsive disorder (13.9%), phobia disorder (10.4%), and psychotic disorder (6.1%). Among all the mental disorders, anxiety disorder and MDD showed the highest prevalence in males (18.2% and 17.4%, respectively) and in females (23.6% and 22.7%, respectively).

In psychiatry, it is important to accurately determine signs of psychiatric disorders in persons so the individuals can be further evaluated and diagnosed through clinical interviews. The GHQ-28 questionnaire and DSM-IV-TR classification of mental disorders were applied in the two-step evaluations of the present study. According to ROC analysis, the traditional cut-off point in the Persian version of the GHQ-28 could specify 91% of suspected persons. Therefore, ROC analysis in our present study verified and supported the validity of the GHQ-28 questionnaire as a screening tool for psychiatric disorders in adults, ages 15 and older.

After the primary evaluation the total rate of suspected psychiatric disorders was 25.8 % and, thus, a secondary evaluation was advised for these cases. In our study, the prevalence rates in males and females were 20.9% and 29.8%, respectively. In similar studies in Iran, the prevalence rate of mental disorders was 21% (14.9% in males; 25.9% in females), as reported by Noorbala et al. Noorbala et al., 1998. Moreover, Mohammadi et al. reported a prevalence rate of 17.1% (10.86% in males; 23.4% in females) Mohammadi et al., 2003, and Rahimi and colleagues reported a prevalence rate of 23% Rahimi-Movaghar et al., 2014.

The higher prevalence of psychiatric disorders in females observed in this study is consistent with other studies. When we evaluated suspected persons for DSM-IV-TR mental disorders, we found that the common mental disorders were MDD, manic disorder and anxiety disorder; moreover, we found that these disorders are more prevalent in females. One explanation for this finding is that females are more prone to stress in similar situations as males Kessler et al., 2005Nolen-Hoeksema, 2001, which may attributable to biological reactions and socio-cultural factors in females Parker and Brotchie, 2010.

Indeed, our results also showed that there is a significant relationship between lower educational level and higher prevalence of psychiatric disorders in responders. Reports in other countries are in accordance with results in this study. The impact of educational level on prevalence of psychiatric disorders has been previously reported Kebede et al., 1999Lin, 1953. Our results also show that unemployment significantly impacts psychiatric disorders, which is consistent with findings observed from a Brazilian study that concluded that unemployed respondents were more likely to have a lifetime (mental) disorder Andrade et al., 2002.

Some limitations of this study are that the diagnostic instrument (summary form of DSM-IV-TR) did not include an assessment of all DSM-IV disorders and that the study was limited to persons of age 15 and above. As the diagnostic validity of the Persian GHQ-28 included only this age group, the results of the present study cannot be generalizable to the whole population.

This study verifies the validity of the Persian version of the GHQ-28 as a screening tool to determine psychiatric disorders in persons of age 15 and above. The GHQ-28 can be a useful instrument to identify individuals with high risk of mental disorders for referral for subsequent interventions.

AD: Anxiety Disorder

DSM: Diagnostic and Statistical Manual of Mental Disorders

GHQ-28: General Health Questionnaire- 28 Items

MDD: Major Depressive Disorder

ROC: Receiver Operating Characteristic analysis

Study concept and design and statistical analysis: FM, YV. The interpretation of data results: YV. The drafting of the manuscript: AD. Final revision of the manuscript for important intellectual content: YV, FM, AD.