Do patients continue to see physicians who are removed from a PPO network?

Objectives: To assess the extent to which excluding physicians from a preferred provider organization (PPO) network causes patients to discontinue using their services and whether the associated changes will result in greater demand for emergency department or inpatient care.
Study Design: Analysis of a natural experiment involving the narrowing of a PPO network operated by the Taft-Hartley Fund. The panel data analysis compared rates of patient discontinuation for excluded physicians before and after the change. The pre-post analysis used matched comparison groups for office visits, emergency department visits, inpatient admissions, and spending for affected patients.
Methods: Claims data analysis used generalized estimating equations and controlled for patient age, sex, health status, and hourly wage. Models examining utilization and spending for 6187 patients who remained with excluded physicians also used a propensity score-matched comparison group identified from among patients who had never seen an excluded physician. Differential response to physician exclusion according to age, health status, and hourly wage was also examined through interaction terms.
Results: The network narrowing reduced the odds of continuing to see an excluded physician (odds ratio, 0.18; P <.001). Patients who continued to see excluded physicians reduced their office visits by a mean of 0.9 visits per year, 0.8 visits more than comparison patients (P <.001). There were no significant changes in emergency department visits or admissions for patients of excluded physicians compared with a matched cohort.
Conclusions: Substantial copayment differentials may be an effective means of encouraging patients to change physicians. Where they are based on reliable information about provider quality and cost, tiered networks may improve value.