Problems of Comorbidity in Mortality After Prostatectomy

OBJECTIVE: In recent studies of patients with benign prostatic hyperplasia (BPH), men undergoing transurethral resection of the prostate (TURP) had higher long-term mortality than men undergoing open prostatectomy. We tested the hypothesis that the higher mortality for patients undergoing TURP could have occurred if these patients were older and sicker at the time of surgery than patients undergoing open prostatectomy. DESIGN AND SETTING: Retrospective cohort study at Yale-New Haven (Conn) Hospital. PATIENTS: Two hundred fifty-two men who underwent TURP or open prostatectomy from 1979 through 1981 for the treatment of BPH. MAIN OUTCOME MEASURES: Five-year mortality adjusted for age and severity of comorbid illness at the time of surgery. RESULTS: The crude 5-year mortality rates were 17.5% (22 of 126 patients) for the TURP group and 13.5% (17 of 126 patients) for the open group. At the time of surgery, however, patients in the TURP group were sicker and older than patients in the open group. As the detail and quality of the assessment of comorbidity increased, the adjusted risk of TURP decreased. Improved classifications of comorbidity in three different forms of statistical analysis did not show an effect of type of prostatectomy on long-term mortality (Mantel-Haenszel relative risk, 1.03; 95% confidence interval, 0.57 to 1.87). CONCLUSIONS: These results suggest that TURP does not increase long-term mortality after surgery for the treatment of BPH. Inadequate accounting for severity of illness may also affect other statistical "adjustments" used in research concerned with patient outcomes.