Gallbladder disease—I. Assessment of validity and reliability of data derived from a questionnaire: A study of 62,739 weight-conscious women

Abstract

This study included 62,739 women who belong to TOPS ( Take Off Pounds Sensibly), and this is perhaps the largest study of gallbladder disease in women ever conducted. The main findings of this study are: 1. 1. The prevalence of gallbladder disease, adjusted for over- and underreporting, was calculated to be 15.1 per 100 women and was not appreciably different from the unadjusted rate of 15.7 previously reported [6]. 2. 2. The estimated reliability of the gallbladder question was found to be 87%. 3. 3. When a small sample of doctors whose questionnaire indicated absence of gallbladder disease and therefore, disagreed with the patient's history of gallbladder disease were requestioned, they changed their response. 4. 4. There was 98% physician confirmation (telephone interviews) of positive diagnosis of gallbladder disease for women who completed the narrative section of the question; 68% of the positive diagnosis of gallbladder disease for women without the narrative section of the questionnaire could be confirmed by the physician. 5. 5. Underreporting of gallbladder disease was conservatively estimated to be 1.6% of the total number with disease. 6. 6. Overreporting of gallbladder disease was estimated to be 12.7% of the total number with disease.