Diagnostic values of digital rectal examination, prostate specific antigen and trans-rectal ultrasound in men with prostatism.

OBJECTIVE To determine the diagnostic values of digital rectal examination (DRE), prostate specific antigen (PSA) and trans-rectal ultrasound (TRUS) individually and in combinations in men aged 50 years and above presenting with prostatism. DESIGN A prospective, descriptive, cross-sectional, hospital-based study. SETTING The urology ward of Kilimanjaro Christian Medical Centre (KCMC), a 500 bed tertiary hospital in the Kilimanjaro region, Tanzania. SUBJECTS Ninety four consecutive admissions of men aged 50 years and above admitted with urinary symptoms suggestive of prostatism. MAIN OUTCOME MEASURES Primary outcome measures included race and age of patient; Positive predictive values, sensitivities and specificities for DRE, PSA and TRUS individually and in combinations and histology of the prostate specimens submitted after Tru-cut, TURP or open prostatectomy. The secondary outcome measures were mean PSA and PSA density. RESULTS There was a prostate adenocarcinoma incidence of 25.5%; all found among patients with PSA levels greater than 10 ng/ml. The positive predictive value (PPV), sensitivity and specificity of DRE for prostate cancer were 0.67%, 66.7% and 88.6% with an accuracy of 82.8%; while for TRUS, the respective values were 0.58%, 58.3% and 85.7% with an accuracy of 78.7%. PSA alone had a positive predictive value of 0.16. A combination of abnormal DRE and PSA (more than 4.0 ng/ml) had a positive predictive value (PPV) of 0.75 while when DRE, TRUS and PSA were all abnormal, the PPV rose to 0.80. CONCLUSION A combination of DRE and PSA yields 75% diagnostic sensitivity for prostate cancer and is reliable enough to exempt TRUS where not available since it only adds 5% to this strong diagnostic combination.