Peter Franks, A. Colin Cameron and Klea D. Bertakis

"On Being New to An Insurance Plan: Health Care Use Associated with the First Years in a Health Insurance Plan"

Annals of Family Medicine, 2003, Sept/Oct, 156-161.

This paper compares health care utilization and costs in the first year of being in a health insurance plan with subsequent years. We used claims data from an independent practice association (IPA)-syle managed care organization in the Rochester, NY, metropolitan area from 1996 through 1999. Cross-sectional and panel analyses of up to 4 years of claims data were conducted, involving 335,547 adult patients assigned to the panels of 687 primary care physicians (internists and family physicians).  Multivariate analyses, adjusting for age, sex, case-mix and socioeconomic status derived from ZIP codes, examined the relationship between the first year of health insurance and Papanacilaou tests, mammograms in women older than 40 years, physician use, avoidable hospitalization, and expenditures.  After multivariate adjustment, the first year of insurance was associated with a higher risk of not getting a mammogram, a higher risk of avoidable hospitalization, greater likelihood of visiting a physician, and higher expenditures, especially for testing. There was no relationship, however, between Pap test compliance and year of enrollment.  The findings suggest that their might be adverse clinical and financial implications associated with changing insurance.