Evaluation of the clinical value of a simple flowmeter in the management of male lower urinary tract symptoms

Abstract

Study Type - Diagnostic (exploratory cohort) Level of Evidence 3b What's known on the subject? and What does the study add? Electronic uroflowmetry reasonably predicts the likelihood of bladder outlet obstruction (BOO) and risk of AUR. This low-cost device, Uflowmeter(™) , allows men to perform uroflowmetry at home with ease and the results are compatible with that of electronic uroflowmentry. It can also estimates risk of AUR and the need for TURP to relieve LUTS.

Objective: To show the clinical value of a simple flowmeter, which has been devised to measure uroflow on an ordinal scale (<10, 10-15, 15-19 and >19 mL/s) at home, for the management of male lower urinary tract symptoms (LUTS).

Patients and methods: A total of 186 men with LUTS were enrolled in the study. The mean (range) follow-up was 220 (68-431) days. The men's mean (range) age was 65.5 (46-83) years, mean (range) maximum urinary flow rate (Qmax) 12.8 (4.3-39.5) mL/s, mean (range) voided volume 294.8 (151-686) mL; mean (range) postvoid residual urine volume (PVR) 50 (0-303) mL and mean (range) International Prostate Symptom Score (IPSS) 13.5 (1-31). The men underwent electronic uroflowmetry ('clinic uroflowmetry') and completed an IPSS questionnaire in the clinic. They then conducted 10 measurements with the device at home ('home uroflowetry'). The uroflowmetry and IPSS questionnaire were repeated 2 weeks later. Quadratically weighted Kappa analysis (κ) of the home uroflowmetry vs. clinic uroflowmetry, and of the sensitivity and specificity of the home uroflowmetry values to correspond to the mean Qmax of clinic uroflowmetry (<10, 10-15, 15-19 and >19 mL/s) was performed. Similar analyses were performed for the IPSS. Kaplan-Meier analysis was performed to evaluate whether home uroflowmetry was able to prognosticate acute urinary retention (AUR) or the need for transurethral resection of the prostate (TURP).

Results: The home uroflowmetry values (κ= 0.84, 95% confidence interval [CI]: 0.78-0.90) were superior to the IPSS (κ= 0.083; 95% CI: 0-0.173) in correlating with the mean Qmax of clinic uroflowmetry. Home uroflowmetry was most sensitive in identifying a mean Qmax of >19 mL/s (sensitivity: 0.99; 95% CI:0.97-1.00) and most specific in identifying a mean Qmax of <10 mL/s (specificity: 0.90; 95% CI:0.83-0.94). The home uroflowmetry works best in ruling out a mean Qmax of <19 mL/s (diagnostic odds ratio [DOR]= 349.3; 95% CI:40.24-3037.7), followed by a mean Qmax of <15 mL/s (DOR = 91.02; 95% CI:31.23-265.23) and a mean Qmax of <10 mL/s (DOR = 32.04; 95% CI:14.0-73.19). Men with a home uroflowmetry value ≤10 mL/s were more likely (n= 6; 8.8%) than those with a home uroflowmetry value >10 mL/s (n= 2; 1.7%) to develop AUR or require TURP (log-rank test: P= 0.017; hazard ratio:5.61(95% CI:1.10-28.64)). The IPSS failed to display the same discriminative capability.

Conclusion: Home uroflowmetry using this simple device is a satisfactory estimation of clinic uroflowmetry using an electronic flowmeter and can predict the significant progression of male LUTS.