Gender-related measurement invariance on the Self-Reporting Questionnaire (SRQ-20) for global mental distress with older adults in Puerto Rico

Background Common mental disorders (CMD) vary by age, gender, and culture. This study: (1) examined the factor structure of the 20-item Self Reporting Questionnaire (SRQ-20) and (2) explored gender-related measurement invariance in the SRQ's performance with older adults in Puerto Rico, a U.S. island territory and associate member of the UN Regional Commissions. Methods We merged data from two cross-sectional studies on mental health status and needs of older adults in Puerto Rico (N = 367). The first study was conducted in 2019, two years after Hurricane Mar & iacute;a devastated the island (N = 154); the second study, in 2021, assessed knowledge, attitudes and practices (KAP) concerning COVID-19 (N = 213). We used chi-square and t-tests to examine gender differences in each SRQ item and assessed internal consistency reliability with Cronbach's alpha and McDonald's omega (values > 0.70). We ran two CFA models, then multigroup CFA to test for gender-related measurement invariance. We used weighted least square mean and variance adjusted (WLSMV) estimation to account for the binary response options in the SRQ-20 and Mplus version 8.4 for analyses. There were no missing data for any SRQ-20 items. Results The SRQ-20 had strong internal consistency reliability (alpha = 0.89; omega = 0.89). Female scores were higher than males scores (t = -2.159, p = .031). Both unidimensional and two-factor models fit the data well. We selected the more parsimonious unidimensional model, which is most widely used in practice. Standardized factor loadings were 0.548 to 0.823 and all were statistically significant (p < .001). We tested gender invariance with the one-factor model. Our findings did not support invariance. Conclusion We favored the unidimensional model. First, the SRQ-20 was designed to assess global distress. Also, physical symptoms have both somatic and psychological components, so their co-occurrence makes a single-factor model more meaningful. Finally, since older adults experience more physical health problems, instruments that emphasize both types of distress may provide a more accurate measure than those that exclude somatic symptoms. Using the unidimensional model, the SRQ-20 was not invariant, meaning that it performed differently for male and female participants. Future studies of common mental disorders with older adults in Puerto Rico should consider using the SRQ-20 for research and practice and should determine appropriate threshold scores for men and women.