Diffusion of good practices of care and decline of the association with case volume: the example of breast conserving surgery

BACKGROUND Several previous studies conducted on cancer registry data and hospital discharge records (HDR) have found an association between hospital volume and the recourse to breast conserving surgery (BCS) for breast cancer. The aim of the current study is to depict concurrent time trends in the recourse to BCS and its association with hospital volume. METHODS Admissions of breast cancer patients for BCS or mastectomy in the period 2000-2004 were identified from the discharge database of the Veneto Region (Italy). The role of procedural volume (low < 50, medium 50-100, high > 100 breast cancer surgeries/year), and of individual risk factors obtainable from HDR was assessed through a hierarchical log-binomial regression. RESULTS Overall, the recourse to BCS was higher in medium (risk ratio = 1.12, 95% confidence interval 1.07-1.18) and high-volume (1.09, 1.03-1.14) compared to low-volume hospitals. The proportion of patients treated in low-volume hospitals dropped from 22% to 12%, with a concurrent increase in the activity of medium-volume providers. The increase over time in breast conservation (globally from 56% to 67%) was steeper in the categories of low- and medium-volume hospitals with respect to high caseload. CONCLUSION The growth in the recourse to BCS was accompanied by a decline of the association with hospital volume; larger centers probably acted as early adopters of breast conservation strategies that subsequently spread to smaller providers.