Development, reliability and validity testing of Postgraduate Stressor Scale: a cross-sectional study of five-factor stressors influencing anxiety and depression in medical postgraduates

Identifying the stressors of postgraduate students is essential for understanding the causes of mental health problems and implementing targeted interventions. Based on the stress process theory, this study aims to develop a stressor scale applicable to contemporary postgraduate students and test its reliability and validity. The scale is further applied to medical postgraduates to explore their stress levels and the impacts of stressors on anxiety and depression.

This study established the scale dimensions and developed the initial scale through literature review and semi-structured interviews with 20 postgraduate students. Following revision based on a pilot survey of 200 postgraduate students, exploratory factor analysis and reliability analysis were conducted on 267 postgraduate students to finalize the formal scale. A cross-sectional study was conducted using stratified cluster sampling. A total of 666 medical postgraduate students from two medical colleges in Chongqing were surveyed using the newly developed Stressor Scale, Patient Health Questionnaire-9 items (PHQ-9), and Generalized Anxiety Disorder-7 (GAD-7). Confirmatory factor analysis was performed to assess the levels of stressors, anxiety, and depressive mood. Hierarchical regression analysis was employed to examine the influence of stressors on anxiety and depressive mood.

Exploratory factor analysis of the postgraduate students identified 5 distinct dimensions: academic stressor (5 items), employment and career stressor (7 items), financial stressor (4 items), supervisory stressor (8 items), family and romantic stressor (5 items). Reliability analysis showed strong internal consistency, with Cronbach's ɑ coefficients ranging from 0.85 to 0.94 and split-half coefficients of 0.79 to 0.93 for both the total scale and individual dimensions. Confirmatory factor analysis conducted on medical postgraduate students demonstrated a good fit, with χ²/df=3.88, comparative fit index (CFI)=0.93, Tucker-Lewis Index (TLI)=0.92, root mean square error of approximation (RMSEA)=0.06, and standardized root mean squared residual (SRMR)=0.07. The convergent validity was good, with average variance extracted (AVE)=0.50 to 0.72 and construct reliability (CR)=0.83 to 0.93. The discriminant validity was satisfactory, with the square roots of AVE for all dimensions ranging from 0.71 to 0.85, all of which were greater than the maximum correlation coefficients between the corresponding factor and other factors. The survey showed that academic stress (2.17±0.74), employment and future stress (1.67±0.68), and financial stress (1.59±0.76) were the 3 major stressors for medical postgraduates. Hierarchical regression analysis indicated that after adjusting for demographic variables and negative emotions (depression and anxiety), employment and future stressor (β=0.19, P<0.001) and family and romantic stressor (β=0.07, P<0.05) independently and positively predicted anxiety; academic stress (β=0.07, P<0.05), employment and future stress (β=0.12, P< 0.01), and financial stress (β=0.08, P<0.05) independently positively predicted depression in medical postgraduates.

The newly developed Five-Factor Postgraduate Stressor Scale demonstrates good reliability and validity, and can be used to assess the stressor levels in postgraduate students. Academic stress is the predominant stressor for medical postgraduates. Stressors can independently and positively predict their anxiety and depression. Different stressors exert differential impacts on various negative emotions (anxiety and depression).