Impact of patient socioeconomic status on physician profiles: a comparison of census-derived and individual measures.

BACKGROUND: Patient education has been shown to affect physician performance profiles. It is not known whether census-derived measures of patient socioeconomic status (SES) show comparable effects.
OBJECTIVE: The objective of this study was to compare the effects on physician profiles for patient satisfaction and physical and mental health of adjustment for patient SES derived from patient addresses geocoded to the census block group level, zip codes, and patient education.
DESIGN: This was a cross-sectional survey of patients in physician practices.
SETTING: Subjects came from adult primary care practices in western New York. PARTICIPANTS: A random sample of 100 primary care physicians and 50 consecutive patients seen by each physician participated in the study. MEASUREMENTS: Independent variables were census-derived (block group and zip code) patient SES and patient-reported education. The outcomes were physician ranks for patient satisfaction (Patient Satisfaction Questionnaire) and physical and mental health status (SF-12). RESULTS. In empirical Bayes models that adjusted for patient age, age squared, gender, insurance, and case mix, both the census-derived measures (block group and zip code) of SES and education had similar effects on each of the physician profiles. CONCLUSIONS. The results suggest that SES derived from either patient addresses geocoded to the census block group level or zip codes may offer a convenient alternative to individually collected SES when adjusting physician profiles for the socioeconomic characteristics of physicians' practices. The relative ease of using zip codes compared with geocoded addresses and loss of information associated with incomplete matching during geocoding suggest that zip code-derived SES may be preferable.