Korean versions of the Perceived Stress Scale (PSS-14, 10 and 4): psychometric evaluation in patients with chronic disease.

BACKGROUND The Perceived Stress Scale (PSS) is a representative instrument used to measure stress. The original PSS comprises 14 items (PSS-14) in two subscales, but 10- and 4-item versions are also available (PSS-10 and 4, respectively). The target populations of psychometric studies using the PSS have far mainly comprised college students, and the underlying constructs of the PSS versions are controversial: one factor vs. two factors and first order vs. second order. OBJECTIVE The aim of this study was to evaluate the psychometric properties of the Korean versions of the PSS-14, 10 and 4 (designated KPSS-14, 10 and -4, respectively) in patients with chronic disease. METHODS The PSS-14, 10 and 4 were translated into Korean using forward and backward translation. Factorial construct validity was tested using both exploratory and confirmatory factor analyses. Item convergent validity and item discriminant validity were tested. Concurrent validity was examined using the Center for Epidemiologic Studies-Depression scale. Known-groups validity was analysed using t-test and effect size. Reliability was tested using Cronbach's alpha and the intraclass correlation coefficient. RESULTS Exploratory factor analysis supported a two-factor model for all Korean versions of the PSS, and confirmatory factor analysis indicated that the model fit the KPSS-10 well and the KPSS-4 only marginally. The testing of item convergent and discriminant validity revealed a 100% scaling success. As expected, all scores in the KPSS-14, 10 and 4 were moderately correlated with depression scores and differed significantly according to gender. The Cronbach's alpha for the KPSS-14 and 10 exceeded the criterion of 0.70. The intraclass correlation coefficient values of all three Korean versions were satisfied. CONCLUSIONS The KPSS-10 exhibited a first-order, two-factor construct, and excellent reliability and validity were established for Korean patients with chronic disease. The psychometric properties of the shortest version, KPSS-4, were only marginally acceptable.