ITEM NONRESPONSE TO LIFE-STYLE ASSESSMENT IN AN ELDERLY COHORT

Background. Greater attention is being paid to data quality in surveys of older age groups. In this paper patterns of item non-response are examined in a health risk appraisal instrument administered to an elde rly cohort participating in a randomized preventive intervention study . Methods. The association between demographic and health status facto rs with the number of non-responses out of 174 items was examined at b aseline and at the 12-month follow-up on 1791 subjects. Results. Overa ll, non-response decreased from baseline to 12 months. The pattern was consistent across the seven major components of the questionnaire. Un ivariate analyses at baseline found that item non-response increased s ignificantly (P < 0.05) with age, being female, being unmarried, lower annual income, less education, and poorer personal health ranking. Po lychotomous logistic regression identified age and personal health ran king as statistically significant at both baseline and 12-month follow -up assessments after controlling for all other factors. In addition, education was significant at baseline. Conclusions. These results help to identify subgroups of elderly participants who contribute to non-r andom patterns of missing data.