Determination of risk factor associations with questionnaire outcomes: A methods case study

Increasingly in biomedical studies, health status is inferred through a ser ies of questionnaire item responses. Challenges for analyzing associations between such responses and risk factors include multiplicity-many indicator s must be combined to derive summary statements about health status, and me asurement error-persons' self-report fluctuates due to causes other than su bstantive health changes. In order to deal with these challenges, the autho rs propose a strategy which comprises three methods: 1) score the item resp onses, then regress the score on predictors; 2) regress each item response on predictors, accounting for within-person associations; and 3) summarize and analyze the item responses jointly, using a latent variable model. The authors develop modeling and diagnostic procedures for method 3. They then show how the three-method analytic strategy can be used to solve the proble m of determining which aspects of vision are associated with self-reported functioning in activities that require seeing at a distance. They demonstra te that methods 2 and 3 illuminate basic findings from method 1 by adding s pecificity, describing patterns as well as severities of health impairments , and identifying isolated items that relate to risk factors differentially than others. They conclude that the three-method strategy specifies how ri sk factors determine questionnaire-based health outcomes substantially bett er than any of the methods in isolation.