Systematic bias in self-reported annual household incomes among unpartnered elderly cardiac patients

The purpose of this exploratory study was to examine whether specific patient characteristics were associated with not reporting individual incomes among elderly unpartnered cardiac patients. Two hundred forty-seven unpartnered patients (age, >/=65 years) who were admitted with coronary artery disease to one of five university medical centers were interviewed during their hospitalization. Their average age was 76 years (SD = 6.3 years, range = 65-101 years). Of the sample, approximately 34% were men, 92% were Caucasian, 19% had less than 12 years of education, and 55% had at least 12 years (but not more than 16 years) of education. Approximately 13% of the patients did not report their annual household income. In a logistic regression analysis, higher education and greater social and economic satisfaction were significantly related to refusal to self-report income after controlling for age and sex (p < .05). The interaction between education and sex was not significant in the model (p > .05). Our findings indicate that there was a potential systematic bias regarding self-reporting of annual household income. Thus, this systematic bias needs to be examined before performing a multivariate analysis that includes income as a covariate.