Multivariate models of self-reported health often neglected essential candidate determinants and methodological issues.

BACKGROUND AND
OBJECTIVE: Self-reported health is an important indicator of overall well-being that may be influenced by diverse parameters. We intended to evaluate the variety of candidate determinants used in models of self-reported health (SRH) and to examine the methodological problems encountered in multivariate models used in recent studies in this field. STUDY DESIGN AND
SETTING: Medline searches identified articles published in 2002 in which SRH was included as an outcome, at least one other variable was used as a determinant of SRH, and the study population was not defined by the presence of specific diseases.
RESULTS: Of 1,991 initially identified reports, 56 were eligible. In 91% of the eligible articles, multivariate models were used. In total, 133 different determinants of SRH were considered (median 7 determinants considered per study with multivariate models). The proportions of studies with problems in multivariate modeling were: overfitting, 10%; nonconformity to a linear gradient, 29%; no report of tests for interactions, 63%; unspecified coding of variables, 49%; and unspecified selection of variables, 29%.
CONCLUSION: Models that try to identify what influences SRH should consider appropriate lists of candidate determinants, with proper attention to methodological aspects of multivariate modeling.