Background. Screening diagnostics of the risk of depression in healthy controls and various mental illnesses for the purpose of timely seeking specialized help requires the elaboration of critical values of indicators as well as calculation of sensitivity and specificity.

Objectives. The study had its purpose to reveal the critical values of the scales for assessing anxiety, depression, and quality of life in patients with affective disorders and schizophrenia.

Study Participants. 277 individuals participated in the study, including 162 adults without mental illness (control group), 47 patients with affective disorders and depressive syndrome, and 68 patients with schizophrenia.

Methods. For data collecting the following standardized methods were used: The Beck Anxiety and Depression Inventories BAI and BDI-II (Beck et al., 1988; Beck et al., 1996), Center for Epidemiological Studies Depression Scale (Radloff, 1977), SCL-90R (Derogatis, 1983), the Satisfaction With Life Scale, the Scale for Positive and Negative Experiences (Diener et al., 1985; Diener, 2010), the Quality of Life and Satisfaction Questionnaire (Stevanovic, 2011). Data processing methods included descriptive statistics, ROC analysis, calculation of sensitivity and specificity, assessment of reliability and consistency, methods for comparing groups, and correlation analysis.

Results. When assessing the differential abilities of anxiety and depression scales, while comparing patients with depressive syndrome in affective disorders and respondents in the control group, the area under the curve in the ROC analysis was significant and amounted to 0.79–0.87. The maximum values were found for the Beck Depression Inventory, Center for Epidemiological Studies Depression Scale, and the depression subscale of the SCL-90R. The depression subscale of the SCL-90R questionnaire is only slightly inferior in psychodiagnostic capabilities to the Beck Depression Inventory and Center for Epidemiological Studies Depression Scale; however, its cutoff values can be recommended at 11 points and 23 points. The 18 items selected from all the inventories implemented in the study form a scale that allows to distinguish between patients with depressive syndrome in schizophrenia and in affective disorders (Cronbach's alpha 0.91 for affective disorders and 0.93 — for schizophrenia). At a cutoff value of 1.59 points, the sensitivity for distinguishing patients with affective disorders and schizophrenia is 72.3%, and the specificity is 78.1%. A content analysis of the items indicates that patients with affective disorders are more likely to report negative obsessive thoughts, criticism and self-rejection, somatic complaints, and difficulty concentrating.

Conclusions. The clinical cutoff for mild depression on the Beck Depression Inventory is 13 points, and for moderate depression — 19 points. The clinical cutoff point for mild depression on the Center for Epidemiological Studies Depression Scale is 17 points, and for moderate depression — 28 points.