Overactive bladder (OAB) is a clinical syndrome whose diagnosis is at large dependent on patient-reported symptoms. The ICS-IUGA Joint Terminology Standardization Report defines OAB as the condition characterized by urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence, in the absence of urinary tract infection (UTI) or other obvious pathology. Due to the weak association between OAB and detrusor overactivity (DO) in urodynamics, the focus of researchers has been shifted to identifying biomarkers that could enhance the diagnosis of the syndrome.
In this large retrospective study of women with lower urinary symptoms, Futyma and co-authors propose flow index (FI), derived from simple uroflowmetry, as a non-invasive biomarker to distinguish women with OAB. They calculate FI as the average urethral flow divided by the maximal urethral flow and demonstrate that this biomarker is unrelated to the voided volume. By reviewing 757 urodynamic investigations in women with lower urinary symptoms, divided in 4 groups according to their most bothersome symptom, they found that women with pure OAB symptoms have a significant lower FI than women with pure SUI (mean 0.45 ± 0.08 vs. 0.53 ± 0.09, respectively; P<0.001). The same trend was observed when comparing women with OAB-predominant MUI and those with SUI-predominant OAB (0.48 ± 0.11 vs. 0.51 ± 0.09, respectively; P<0.01). Women with pure OAB or OAB-predominant MUI also demonstrated a lower flow index when compared with those reporting SUI or SUI-predominant OAB. Further analysis revealed a significant difference in the FI between patients complaining of nocturia and urgency, compared to women who were free of such symptoms (mean 0.48 ± 0.1 vs. 0.53 ± 0.1, respectively; P<0.001).
The AUC for the FI was 0.72 indicating a good marker for distinguishing OAB patients, offering a sensitivity and a specificity of almost 70%, when a cut-off value of 0.45 was considered. Previous studies have shown a poor correlation between OAB symptoms and urodynamically proven DO, and given the lack of normative uroflow values, FI appears a promising tool in helping physicians confirm the diagnosis of OAB. Other urinary, serum, and imaging biomarkers have been explored as potential diagnostic aids, however so far only increased urinary nerve growth factor levels (NGF) have been strongly linked with OAB. Further confirmation from other research groups of the potential diagnostic value of uroflow parameters in OAB patients is eagerly awaited.
Article by the Publication & Communications Committee
Use of uroflow parameters in diagnosing an overactive bladder-Back to the drawing board. Futyma K, Nowakowski, Bogusiewicz M, Ziętek A, Wieczorek AP, Rechberger T.Neurourol Urodyn. 2017 Jan;36(1):198-202. doi: 10.1002/nau.22898.