EFFECT OF DIGITAL RECTAL EXAMINATION ON SERUM PROSTATE-SPECIFIC ANTIGEN IN A PRIMARY-CARE SETTING

Background: Measurement of serum prostate-specific antigen (PSA) and d igital rectal examination (DRE) are commonly used for prostate cancer screening. Clinicians have been advised to avoid measuring serum PSA a fter DRE because of the possibility of spurious elevation. However, st udies in healthy volunteers have found no change. We sought to determi ne whether DRE performed by internists affects PSA levels in a primary care clinic population. Methods: Men older than 49 years enrolled in a Veterans Affairs internal medicine clinic were eligible for the stud y. For all patients, prostate size and nodularity were assessed by DRE . Blood for determination of PSA levels was drawn immediately before D RE and 30 minutes after DRE. All patients completed a questionnaire re garding voiding. Results: Two hundred two men aged 50 to 85 years (mea n, 67 years) were enrolled and had complete data. The mean PSA level i ncreased by 0.26 mu g/L after DRE (P<.001). Six patients (2.9%; 95% co nfidence interval, 0.6% to 5.3%) bad an increase in PSA level from les s than 4 mu g/L to more than 4 mu g/L after DRE. There was a statistic ally significant but weak correlation between voiding score and PSA le vel (coefficient, .17; P=.02). Patients with an enlarged prostate glan d had higher PSA levels than did patients with normal prostates or bor derline results of examination. Nodularity did not predict an increase d PSA level. Conclusions: We conclude, in an elderly veteran populatio n, that DRE causes a statistically significant but clinically insignif icant increase in serum PSA level. Additionally, we found that symptom s and physical examination results cannot be used to select a populati on for whom PSA screening would likely be useful.