Reliability and Validity Testing of the Revised 12-Item Short-Form Health Survey in Older Adults

Abstract

The SF-12 Short Form Health Survey was developed to describe mental and physical health status of adults, and to measure the outcomes of health care services. The purpose of this study was to test the reliability and validity of this measure in a sample of 185 older adults living in a continuing care retirement community. The mean age of the participants was 86 + 6.1 and the majority were female (82%), unmarried (82%), Caucasian (99%), and all had at least a high school education. Initial testing of the SF-12 measurement model as proposed by Ware, Kosinski, and Keller (1995) demonstrated that the model did not fit the data (chi-squared/<df = 7.8). The model was revised based on modification indices and the revised model provided evidence of reliability (alpha coefficients of .70, and .89; the majority of the R2 values were greater than .50), and validity as there was improved fit of the model to the data (X2 difference of 123, df difference of 1.0, p < .05). There was also evidence of construct validity, based on hypothesis testing, with a statistically significant correlation between physical health and number of chronic illnesses (r = .33, p < .05) and mental health and chronic illnesses (r = .27, p < .05), and a statistically significant difference in physical health (F = 30.5, p < .05) and mental health (F = 18.5, p < .05) between those who exercise regularly and those who do not. The revised SF-12 is a reliable and valid measure of health status in independent living older adults, and has the potential for use as either a predictor or an outcome measure.