The added value of home-uroflowmetry; Analysing an individuals' VV-Qmax curve and inflection point.

Objectives: To analyse individual VV-Qmax plots based on multiple home uroflowmetries and compare these with cross-sectional nomograms.

Methods: Healthy volunteers (16-69 years) without LUTS were asked to take a Minze Homeflow device home to register 25 uroflows. Participants reporting urinary tract disorders, malignancy or medication affecting bladder function were excluded. Dysfunctional voiding curves or participants with less than 15 acceptable flows were also excluded. For each individual, a VV-Qmax scatterplot was visually evaluated and a segmented regression was performed to determine the volume at which inflection occurred.

Results: 145 participants were enrolled. 38 were excluded based on medical history or LUTS, another 3 because the minimum amount of acceptable flows was not reached. This resulted in 104 participants (40M/64F) and 2498 acceptable uroflows with intra-individual differences based on voided volume, urge and time of the day. Individual VV-Qmax plots derived from multiple measurements do not align with the published nomograms based on cross-sectional data. The VV-Qmax curve for an individual demonstrates that Qmax increases with rising voided volumes up to a specific transitional voided volume (VVtrans) of 253ml (in men) and 214ml (in women), after which Qmax remains stable despite further increases in voided volumes.

Conclusion: A single uroflowmetry is insufficient to represents an individuals' voiding pattern. An individuals' VV- Qmax curve may give a better picture and can identify a new parameter, VVtrans, which might be a reflection of a patient's bladder function and urethra patency. Further evaluation and application in clinical LUTS scenarios are needed.