Duration of detrusor overactivity as an independent predictive factor of upper urinary tract deterioration in patients with traumatic spinal cord injury: results of a retrospective cohort study

Objective
To determine whether duration of detrusor overactivity (DO) during a cystometric study is an independent predictive factor of upper urinary tract deterioration (UUTD) in patients with traumatic spinal cord injury (TSCI).

Study design
Retrospective cohort study.

Setting
A rehabilitation facility in Chiang Mai, Thailand.

Methods
Data were obtained from medical records of patients who underwent cystometric evaluation at 6–12 months after TSCI. The independent predictor of interest is the duration of DO, which was evaluated by the DO/cystometry ratio (DOratio). Other conventional urodynamic parameters (maximum detrusor pressure, cystometric capacity, bladder compliance, and detrusor-sphincter dyssynergia) and clinical parameters (age, sex, level and severity of injury, comorbidities, bladder emptying method, and history of urinary tract infection) were determined. The outcome was UUTD, which is indicated by chronic kidney disease (GFR < 60 ml/min/1.73 m2), hydronephrosis, and/or vesicoureteral reflux. Multivariable Cox regression analysis was used to determine the independent associations between DOratio and UUTD by adjusting with all other parameters.

Results
Medical records of 194 patients with TSCI were included in the study. During a combined total of 1260 follow-up years of those patients, 34 UUTD events were identified, indicating an incidence rate of 27.0 cases per 1000 person-years. After adjusting for all other parameters, a high DOratio (≥0.33) was significantly associated with UUTD (hazard ratio = 3.00 [95% CI: 1.12–7.99], p = 0.025).

Conclusion
DOratio may be an independent cystometric predictor of UUTD in patients with TSCI. However, further prospective study is needed prior to applying DOratio as a predictor of UUTD in clinical settings.