Retest reliability of self-reported function, self-care, and disease history.

BACKGROUND

Exposures and outcomes frequently are measured by self-reports in epidemiologic studies. However, compared with objective data based on physiologic or laboratory tests, self-reports may suffer from lower accuracy and reliability. In addition, few reports examine reliability in population subgroups, such as black adults.

METHODS

The authors examined the retest reliability of common self-reports concerning self-care, function, and chronic conditions in a random subsample of 92 middle-aged black subjects from a larger cohort of 998 subjects in St. Louis, Missouri. Subjects completed in-home interviews between September 2000 and July 2001.

MEASURES: Function and self-care measures included 7 basic activities of daily living, 8 instrumental activities of daily living, and 9 items based on the Nagi physical performance scale. Chronic conditions included a list of 11 common diseases and conditions and the 7 items of the Rose Angina protocol. Item level agreement was measured by kappa and scale level agreement was measured by intraclass correlation coefficients.

RESULTS

Function and self-care items demonstrated highly variable agreement with 7 items failing to reach even moderate (kappa = 0.40) levels of agreement. Scale reliability was better, and intraclass correlation coefficients ranged from 0.75 to 0.95. Self-reported chronic conditions all achieved at least moderate agreement, except for angina based on the Rose protocol.

CONCLUSIONS

This study provides evidence that summary measures of function and a number of chronic conditions and diseases are reliable based on self-reports from urban black adults.