Reproducibility of uroflow measurement: Experience during a double-blind, placebo-controlled study of doxazosin in benign prostatic hyperplasia

Objectives. To evaluate the interindividual and intraindividual variation of uroflow measurements in men with benign prostatic hyperplasia (BPH). Methods. A total of 147 men with clinical evidence of BPH underwent two uroflow measurements at each of two screening visits prior to recruitment into a placebo-controlled study of doxazosin in the treatment: of BPH. The maximum and mean flow rates were determined on each occasion. Differences in the mean value of both parameters for the cohort were examined, The intraindividual variability was evaluated using intraclass correlation coefficients and differences in maximum uroflow at each visit were examined. Results. Uroflow measurements for the cohort were reproducible and there was no clinically significant difference in maximum and mean flow rate on each occasion, However, the intraclass correlation coefficients for the mean and maximum flow rate varied between 0.70 and 0.82, indicating that intraindividual variation accounted for a substantial component of the total variation in uroflow observed among these patients. For many individuals, test-retest differences were clinically relevant. Conclusions. For a group of patients, maximum and mean uroflow measurements are reproducible. However, for an individual, these parameters are subject to clinically significant variation and a single measurement may not be representative. This may be important when considering the need for therapeutic intervention.