Measurement equivalence of the Kessler 6 Psychological Distress Scale for Chinese and Korean immigrants: Comparison between younger and older adults

Objectives The Kessler 6 (K6) Psychological Distress Scale is a well‐known instrument to screen for psychological distress of general populations. It is critical to perform the equivalence test of the K6 for Asian immigrant subgroups. Methods The 2012 California Health Interview Survey data were used ( N = 1,210; Chinese = 640, Koreans = 570). Among 1,210, 734 were younger (18–64 years) and 476 were older (65+) adults. It was examined whether parameters in the measurement model is equivalent across the two groups, using multiple‐group analysis. The equivalence tests for Chinese and Koreans were separately performed based on different age groups (younger [18–64] vs. older [65+]). Results The younger group had good model fit ( X 2 = 41.27 [ df = 16, p = .001], X 2 / df = 2.58, Comparative Fit Index [CFI] = 0.99, Goodness of Fit Index [GFI] = 0.98, root mean square error or approximation [RMSEA] = 0.05, standardized root mean residual [SRMR] = 0.03), and the older group also showed good model fit ( X 2 = 41.70 [ df = 16, p  < .001], X 2 /df = 2.61, CFI = 0.98, GFI = 0.97, RMSEA = 0.06, SRMR = 0.04). The model for older group indicated measurement noninvariance between Chinese and Korean immigrants (Δ X 2 = 17.86, Δ df = 5, p = .003, CFI = 0.972, ΔCFI = 0.009). The items “hopeless,” “restless,” and “depress,” were significantly nonequivalent between the two groups. Conclusions Clinicians/researchers should be aware of the potential risk for misclassification when they screen psychological distress of Chinese or Korean older immigrants. Professionals should pay attention to cross‐cultural comparability when interpreting results from the K6.