Association between Proposed Quality of Care Indicators and Long-Term Outcomes for Men with Localized Prostate Cancer

Abstract

Background: We evaluated the validity of a set of 11 quality indicators for prostate cancer radiotherapy and radical prostatectomy by examining their association with outcomes. The selected indicators were: hospital volume, pre-treatment risk assessment, patient consultation with a radiation oncologist, appropriate follow-up care, leg immobilization during radiotherapy, bladder filling during radiotherapy, portal film target localization, use of nerve sparing surgery, operative blood loss, margin status and pelvic lymph node dissection. The selected outcomes were: cause-specific survival, disease-free survival, late morbidity (urinary incontinence, gastrointestinal and genitourinary morbidity), change in node stage from clinical N0 to pathologic N1, and margin status. Methods: Our study sample consisted of 1570 prostate cancer patients who were diagnosed in Ontario between January 1, 1990 and December 31, 1998 who received radical prostatectomy within 6 months of diagnosis (n=646), or curative radiotherapy within 9 months of diagnosis (n=924). Quality of care, outcomes, and potential confounders were measured using patient chart and administrative data. Regression techniques were used to evaluate the associations between quality indicators and relevant outcomes. Results: For patients treated surgically, hospital volume met our test of validity. Patients treated in the lowest volume hospital (0-1 RP/month) were at greater risk of prostate cancer death than patients treated in the highest volume hospitals (7+ RP/month) (HR=5.37 95% CI=1.23-23.46). For patients treated with radiotherapy, leg immobilization and bladder filling during radiotherapy met our test of validity. Patients treated without leg immobilization were more likely to experience urinary incontinence (RR=2.18, 95% CI=1.23-3.87) and genitourinary late morbidities (RR=1.72, 95% CI=1.16-2.56) than patients who received leg immobilization. Patients who were treated with an empty bladder were more likely to experience GU late morbidities (RR=1.98, 95% CI=1.08-3.63) than those treated with a full bladder. The remaining indicators did not meet our test of validity. Conclusion: Our results support the validity of one surgical quality indicator and two radiotherapy quality indicators. Explanations for our non-significant findings, including limited study power, data quality, our definition and measurement of indicators, and a true failure to predict outcome(s) are discussed, and recommendations for further research are presented.