Effect of digital rectal examination on prostate specific antigen levels among patients with lower urinary tract symptoms in Uganda

Abstract

Introduction Prostatic cancer is a major contributor to mortality among men globally. Prostate-specific antigen (PSA) is a screening investigation for cancer of the prostate. The combination of serum PSA and digital rectal examination (DRE) allows early detection of prostate cancer. Studies have revealed that DRE causes an elevation in serum PSA levels. This rise following DRE may be mistaken for the rise associated with malignancy. Most clients in our setting come to the urology clinic as referrals from primary physicians when DRE has been done. There is a significant knowledge gap regarding whether the PSA change following DRE is significant enough to warrant withholding PSA measurement in these patients that come after having DRE; the reason this study was done. Methods This was a single centre prospective longitudinal study done at Ishaka Adventist hospital in which an interviewer administered questionnaire was filled for each patient that consented. After filling the questionnaire, a venous blood sample was drawn, DRE done and 1-hour later, another blood sample drawn. Total PSA was measured for both samples and data analyzed using SPSS version 22. Results Data for 102 participants was analyzed, whose mean age was 61.85 ± 12.73 years. The paired samples T test revealed a small mean increase in PSA following DRE (0.40 ng/ml) that was not significant (p = 0.061). The number of patients whose clinical decision would be affected (changed) by the PSA measured after DRE was 3 (2.9%, CI = 0.0%-6.9%) if cutoff was 3 ng/ml and 2 (2.0%, CI = 0.0%-4.9%) at 4 ng/ml cutoff. The confidence intervals in both scenarios included 0.0%, suggesting that there would be no significant effect on the clinical decision if the PSA was done post DRE. Conclusion. DRE can be used in screening and clinical assessment of prostate cancer without fear of interfering with PSA result interpretation and patient management.