Predictors of variation in office visit interval assignment.

OBJECTIVE: Despite the important influence of ambulatory appointment revisit intervals (RVI) on access to care, physicians receive no formal training in this area and research indicates that there is significant practice variation. Our objective was to examine whether predictors of RVI assignment that we had assessed using vignettes were also significant in the actual patient care setting. DATA SOURCES AND STUDY
DESIGN: A cross-sectional survey of 59 internal medicine residents collected at the end of office visits for patients with hypertension or diabetes. Two hundred and twenty-eight patients seen in 1997 for continuity care in two academic clinics in New Orleans, Louisiana. DATA COLLECTION: The main outcome was RVI in weeks. We assessed the relationship between physician, visit, and patient-level covariates, and RVI assignment in univariate and multivariate analyses using hierarchical linear models. PRINCIPAL
FINDINGS: The mean RVI was 12.4 weeks (range 1-42 weeks) and was similar for patients with diabetes and hypertension. The final model accounted for 35.7% of the variance in RVI assignment and included: perceptions of the patient's systolic blood pressure, disease stability, and compliance; comorbidity, physician age, sex, and identity; and changing therapy for the primary diagnosis. The identity of the physician was the largest contributor to the variance, accounting for 14.7%.
CONCLUSIONS: Intrinsic characteristics of physicians and their subjective interpretations of their patients' disease stability are the most important determinants of ambulatory RVI assignment. Intervening to reduce this variation in practice is challenging because limited research is currently available on the optimum RVI for patients with chronic illnesses such as diabetes and hypertension.