How representative of typical practice are practice-based research networks? A report from the Ambulatory Sentinel Practice Network Inc (ASPN)

OBJECTIVE: To evaluate the patients and practices of family physicians in a national practice-based research network to understand whether results from practice-based research networks are likely to be relevant to other practicing clinicians. STUDY
DESIGN: Survey focused on family physicians that replicated the National Ambulatory Medical Care Survey (NAMCS).
SETTING: The Ambulatory Sentinel Practice Network Inc (ASPN), a practice-based research network, consisting of volunteer primary care practices that serve approximately 350,000 patients. OUTCOME MEASURES: Comparison of visits reported in ASPN with the visits reported in the 1990 NAMCS in terms of patient demographics, reasons for visit, diagnostic and therapeutic services, diagnoses, disposition, and amount of time spent with patients.
RESULTS: Overall, the two samples differed with respect to demographic characteristics of patients, while problems, diagnoses, services, disposition, and time spent with patients were similar. Specific pair-wise comparisons identified areas of difference.
CONCLUSION: The ASPN and possibly other similar practice-based research networks are sufficiently representative of family practice to serve as useful laboratories in which family practice and primary care can be explored.