Detrusor underactivity (DU) is a prevalent condition, affecting up to 48% of men under 70 years old and 12-45% of women(1). While its etiopathogenesis remains to be understood completely, we know it may be consequence of a neurogenic or a non-neurogenic insult, with probable major factors including diabetes, trauma, neurological disorders, bladder outlet obstruction and age-related dysfunction. Though this condition has gained renewed interest, we are still not able to diagnose it without using invasive urodynamic exams. A variety of urodynamic criteria have been proposed to diagnose detrusor underactivity, however, none of these criteria are validated(2).
We assessed the efficacy of different sets of urodynamic criteria (previously published) to diagnose the prevalence of DU diagnosis in a sample of patients with refractory lower urinary tract symptoms. We also studied the correlation between the DU diagnosis and its associated risk factors.

We retrospectively reviewed the urodynamic findings in 506 consecutive patients who had conventional urodynamics between 01/04/2016 and 31/12/2018. 
The terminology used was defined by the International Continence Society report on the terminology for adult male lower urinary tract and pelvic floor symptoms and dysfunction of 2019(3). Patients demographic and clinical issues were assessed (namely risk factors for DU – Diabetes Mellitus, neurological disorders, previous surgeries, radiotherapy and drugs consumption). The presence of DU was assessed according to two different set of diagnostic urodynamic criteria: set A (Bladder Contractility Index (BCI)) and set B (males - BCI, Bladder Outlet Obstruction Index (BOOI) and Bladder Voiding Efficiency (BVE); females- Qmax, PdetQmax and BVE, according with previous literature).
Statistical analysis was by T-Test and Chi-Square analysis and significance determined as P < 0.05.

About 22,5% of patients (n=114) were excluded due to technical issues. A total of 53,75% of patients (n=273) didn't match the diagnostic criteria.
Details on DU patients’ urodynamic findings are detailed in Table 1.
In set A (119 patients; 19 males and 100 females), women with DU were younger than male patients (65,94 years vs 71,89 years). Regarding their comorbidities, male patients had a higher prevalence of Diabetes Mellitus, Parkinson Disease and past urological surgery; women presented with a higher prevalence of past radiotherapy. Concerning medication, women generally consumed higher rates of drugs such as tricyclic antidepressants and opioids; there was no significant difference regarding serotonin selective reuptake inhibitors. Women had more mixed urinary incontinence complaints. Considering the urodynamic findings, women presented with higher Qmax levels, post-void residuals and BVE.
In set B, there was a substantial reduction in DU prevalence; however, it still displayed the same male:female proportion. When comparing their demographics and comorbidities, women were still younger (68 years vs 74,67 years) and had less neurological disorders and consumed higher rates of drugs, as in set A. They also presented with more complaints of stress, urge and mixed type urinary incontinence. There was no difference in the prevalence of Diabetes Mellitus. 
When comparing sets A and B, there was no significant statistical difference in all categories, except in post-void residual in males (p<0,042).

DU affects a considerable proportion of patients referred to our tertiary referral functional urology unit. Using a broader diagnostic criteria (set A), DU was demonstrated in 23,52% (n=119; 84,04% females and 15,96% males)) of the patients submitted to urodynamics. Considering a different set of urodynamic characteristics (set B), the prevalence was of 8,89% (n= 45; 86,67% females and 13,33% males).
Overall, women with DU were younger and had less comorbidities than men. They also presented with higher rates of urgency symptoms and urinary incontinence.
Despite using different urodynamic criteria to classify the patients, which resulted in an important reduction in the DU prevalence, the two sets still presented the same male:female proportion and clinical and urodynamic characteristics. There was no statistical difference regarding their treatment.

Despite using different sets of diagnostic criterion, both groups presented with prevalence rates that correlate with the ones published in previous studies.
In our study, there is no significant statistical difference in clinical or urodynamic patients’ characteristics when using different urodynamic criteria to diagnose detrusor underactivity. There is also no statistical difference regarding their treatment. However, using set B narrowed the number of patients labeled with detrusor underactivity, and simultaneously the number of patients that might benefit from treatment.
There are inherent limitations of our study, since it is a retrospective analysis of an already existing database and it may not reflect the general population, as the patients were referred for an urological evaluation due to functional urological problems. However this study confirms the need for establishing a gold-standard urodynamic definition of detrusor underactivity. More prospective, longitudinal studies are mandatory to ascertain its urodynamic set of diagnostic criteria.

Gammie A, Kaper M, Dorrepaal C, Kos T, Abrams P. Signs and Symptoms of Detrusor Underactivity: An Analysis of Clinical Presentation and Urodynamic Tests From a Large Group of Patients Undergoing Pressure Flow Studies. Eur Urol. 2016;69(2):361-369. doi:10.1016/j.eururo.2015.08.014.
Osman NI, Esperto F, Chapple CR. Detrusor Underactivity and the Underactive Bladder: A Systematic Review of Preclinical and Clinical Studies. Eur Urol. 2018;74(5):633-643. doi:10.1016/j.eururo.2018.07.037.
D’Ancona C, Haylen B, Oelke M, Abranches-Monteiro L, Arnold E, Goldman H, Hamid R, Homma Y, Marcelissen T, Rademakers K, Schizas A, Singla A, Soto I, Tse V, Wachter S, Herschorn S. The International Continent Society report on the terminology for adult male lower urinary tract and pelvic floor symptoms and dysfunction. Neurourol Urodynam. 2019; 1-45. Doi:10.1002/nau.23897