Individualized volume-corrected maximum flow rate correlates with outcome from bladder outlet surgery in men with lower urinary tract symptoms

Abstract

Objectives: To develop a per-patient volume correction for maximum flow rate using multiple home uroflowmetry, and to carry out a pilot study to determine the most prognostically useful volume at which to evaluate this measurement and estimate its relationship with outcome from disobstructive bladder outlet surgery. Methods: A total of 30 men carried out home uroflowmetry using a portable device and completed symptom scores before surgery. This was repeated at least 4 months after surgery. For each man's presurgery flow data, voided volume was plotted against maximum flow rate, and a line of best fit with logarithmic form calculated. This allowed maximum flow rate to be corrected for any volume. Percentage reduction in symptom score and increase in mean maximum flow rate were correlated with volume-corrected maximum flow rates. Results: Corrected maximum flow rate at all volumes showed the expected negative correlation with both outcome measures. A statistically significant correlation occurred for volumes >190 mL, with the best performance at volumes >300 mL. Conclusions: We have devised a novel method allowing estimation of maximum flow rate at any volume, which is a step forward for non-invasive diagnostics. We found this volume-corrected maximum flow rate to correlate significantly with treatment outcome at sufficiently high volumes.