Factors associated with response to medical treatment of benign prostatic hypertrophy with alpha adrenergic blocker (tamsulosin) at the University Teaching Hospitals, Lusaka

Abstract

Benign prostatic hypertrophy (BPH) is a disease affecting the elderly men, which can be treated either medically ( alpha blockers or 5 alpha reductase inhibitors) or surgically. The aim of this study was to identify pre treatment factors that would predict or influence response to medical treatment with an alpha blocker (tamsulosin). This was a cohort study conducted at the University teaching Hospitals in Lusaka, Zambia. It was done over a period of 4 months (December 2017 to April 2018). A total of 71 men with BPH were enrolled out of which 43 (61%) presented with lower urinary tract symptoms(LUTS) and 28 (39%) presented with acute urinary retention (AUR). The pre treatment factors that were analysed included demographic factors, International Prostate Symptom Score (IPSS), duration of symptoms, prostate volume (PV) and prostate specific antigen (PSA). They were then commenced on an alpha blocker and reassessed at two weekly intervals. Outcome was measured as failed medical treatment when patient with lower urinary tract symptoms (LUTS) had no improvement in International prostate symptom score, or when the patient with acute urinary retention failed to void satisfactorily after removal of urinary catheter (TWOC). Results showed that the average age of the acute urinary retention group and lower urinary tract symptoms group was 69 and 66 years respectively. The mean prostate volume was 77.9ml for the acute urinary retention group and 56.4ml for the lower urinary tract symptoms group and this observed difference was statistically significant (P=0.012). The success rate for the lower urinary tract symptoms group was 81.3% with prostate volume being the only significant factor influencing success of treatment. Using the Receiver operating charactoristic (ROC) curve the cutoff value was 50ml (P=0.047). In the patients with acute urinary retention, 21.4% failed to void after the catheter was removed, and there was no significant factor that was associated with failure to void in this group. The pre treatment factor associated with poor response to medical treatment with an alpha blocker is prostate volume with a cutoff value of 50ml. Patients that present with symptoms of BPH with a prostate volume less than 50ml are likely to have a good outcome on medical treatment with alpha blockers. Key words: benign prostatic hypertrophy (BPH), lower urinary tract symptoms (LUTS), acute urinary retention (AUR), prostate volume (PV), International prostate symptom score (IPSS).