Screening Mammography Rate Before and After the 2009 USPSTF Guideline: An Interrupted Time Series Analysis

Research Objective: Mammography remains an effective tool in detecting breast cancer at early stages and reducing breast-cancer-specific mortality. We examine the effect of the 2009 USPSTF guideline on mammography rate using a 5% sample of Medicare female beneficiaries aged 65 to 90, who were alive, with continuous part A and part B coverage and no HMO enrollment throughout each year from 2004-2011.    

Study Design: We used the Interrupted-Time-Series (ITS) design with a non-equivalent dependent variable and segmented regression analysis to evaluate the longitudinal effects of the 2009 USPSTF guideline changes on utilization of breast cancer screening.

Principal Findings: Our initial findings show that the release of 2009 USPSTF guideline results in a sharp drop of 8.3 per 1000 Medicare-eligible women (p-value <0.0001). The rate increases at a pace of 0.3 per month (p-value <0.001), and by the end of 2011, the rate has returned to the pre-2009 guideline level. When stratified by age groups, the guideline shows a stronger effect for women age 70 and older than age 65-69. The rate of pap test shows a similar pattern but less drastic post-2009 USPSTF guideline.     

Conclusion: Consistent with most previous studies that used pre-post comparison, we found the screening mammography rate did not change in the long run after the 2009 guideline. But our study further reveals the incremental effect of policy changes overall and for different age groups.  It appears important for policy organizations to issue concordant, rather than competing guidelines to effect changes in population care.