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Survival after breast cancer treatment: the impact of provider volume
Author(s) -
Bailie Karen,
Dobie Iain,
Kirk Stephen,
Donnelly Michael
Publication year - 2007
Publication title -
journal of evaluation in clinical practice
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.737
H-Index - 73
eISSN - 1365-2753
pISSN - 1356-1294
DOI - 10.1111/j.1365-2753.2006.00748.x
Subject(s) - medicine , breast cancer , proportional hazards model , multivariate analysis , disease , survival analysis , hormonal therapy , case mix index , cancer , medical record , radiation therapy , stage (stratigraphy) , oncology , surgery , paleontology , nursing , biology
Background Research has not paid sufficient attention to the need for adequate case‐mix adjustment in studies of the relationship between provider volume and performance. This study attempted to address this limitation by capturing and including 5‐year survival outcomes and a wide range of case‐mix variables in multivariate analyses of the volume–outcome relationship relating to breast cancer treatments. Methods All patients diagnosed with invasive primary breast cancer during 1996 ( n = 809) were included. Patient, disease and treatment data were extracted from medical records; survival data were corroborated using official death registrations. A Cox proportional hazards approach was used to model relationships between patient, disease and service variables and risk of death. Results There were 262 deaths among 807 patients followed up; overall 5‐year survival was 70%. Advancing age, higher levels of co‐morbidity, late‐stage disease, more positive nodes, and high‐grade tumour were independently associated with lower survival ( P < 0.05). Patients who received hormonal therapy (HR 0.50, 95% CI 0.28–0.89) and radiotherapy (HR 0.73, 95% CI 0.53–1.03) had a survival advantage. Using a cut‐off point of ≥30 cases per annum, survival was lower for patients treated in low volume settings (HR 1.47, 95% CI 1.09–1.96) after adjustment for case mix. Conclusions There was some evidence to support treatment in high volume settings although patient and disease variables were the major determinants of survival for patients with breast cancer.