Quality of care indicators and their related outcomes: A population-based study in prostate cancer patients treated with radical prostatectomy.

Introduction: We evaluated the validity of 8 quality of care indicators for prostate cancer patients treated curatively with radical prostatectomy (RP) by examining their association with indicator-relevant outcomes.

Methods: We conducted a population-based retrospective cohort study of 646 prostate cancer patients diagnosed between 1990 and 1998 who received RP within 6 months of diagnosis. Data were collected from treating charts and linked to registry and administrative data. Quality indicators included: hospital volume, pre-treatment risk assessment, consultation with a radiation oncologist, appropriate follow-up care, nerve-sparing surgery, units of blood transfused, surgical margin status, and pelvic lymph node dissection during RP. Indicator-relevant outcomes were selected a priori by clinical members of the research team. The associations between indicators and their relevant outcomes were analyzed using regression techniques, to control for potential confounders.

Results: Of the quality indicators evaluated, only hospital volume was statistically significantly associated with the gradient in the expected direction. Patients treated in the lowest-volume hospitals (<1 RP/month) had lower cause-specific survival rates compared to patients treated in the highest-volume hospitals (≥7 RP/month) (HR=4.71 95%; CI 1.06-20.82). Completeness of follow-up care was associated with cause-specific survival but in the opposite direction to our hypothesis.

Conclusion: The structural indicator of hospital volume was associated with cause-specific survival in accordance with our a priori hypothesis. Our negative findings for completeness of follow-up care call its validity into question. Issues of statistical power and measurement accuracy may have affected our validation of the remaining indicators underscoring the challenges in assessing the impact of accepted quality indicators.