Reliability and validity of the Katz Adjustment Scales in an epilepsy sample

Abstract

Development of quality of life measures de novo is time-consuming and expensive, and a number of instruments are already available for general use. Reevaluation and refinement of quality of life tools are needed to improve the existing pool of measures. In this study, data from a sample of 328 epilepsy patients were used to revise a measure of social adjustment and emotional status developed in the 1960s, the 127-item form R1 of the Katz Adjustment Scales (KAS-R1). Using a comprehensive item analysis procedure, we increased the number of items used in scoring the KAS-R1 from 76 to 113 and substantially improved the reliability of scales in both the original sample of 328 epilepsy patients and in a second administration to a 'cross-validation' sample of 193 epilepsy patients. Support for the validity of the revised KAS-R1 scoring system was obtained in a known groups analysis of patients who had previously undergone surgery for epilepsy: mean scores were significantly higher (p < 0.05) on 11 out of 14 scales in the revised KAS-R1 for patients who were completely seizure-free compared to patients who were having seizures with loss of consciousness, after adjusting for age, gender, and anticonvulsant medication use.