To determine the risk of clinical progressions in men with mild lower urinary tract symptoms of bladder outlet obstruction and identify the predictors for progression in this group of men.

A total of 397 men who presented to the urology clinics with mild symptoms of bladder outlet obstruction (International Prostate Symptom Score less than 8) were analyzed in this longitudinal study conducted during a 4-year period. They began with the watchful waiting protocol and were followed up every 3 months for 48 months. Age, International Prostate Symptom Score (IPSS), divided into obstructive symptom score and irritative symptom score, serum prostate-specific antigen level, total prostate volume, transitional zone volume, urinary flow rates, and postvoid residual urine volume were documented.

The cumulative incidence of clinical progression, defined as worsening of the IPSS with migration to the moderate symptom group (IPSS 8 to 18) or severe symptom group (IPSS 19 to 35) and an increase in IPSS of more than 2 points, was 6%, 13%, 15%, 24%, 28%, and 31% at 6, 12, 18, 24, 36, and 48 months, respectively. Nineteen patients (4.9%) developed acute urinary retention within the 48-month follow-up period. Of these 19 patients, only 2 (0.6%) required transurethral resection of the prostate. The variables of importance for disease progression in the artificial neural network analysis were, in order of statistical significance, prostate-specific antigen level, obstructive symptom score, and transitional zone volume.

The risk for men with mild symptoms of bladder outlet obstruction to progress clinically and develop complications such as acute retention of urine is moderate. Prostate-specific antigen, obstructive symptom score, and transitional zone volume were identified as important risk factors.