Hypothesis / aims of study
Detrusor underactivity (DU) is not a rare voiding dysfunction associated with lower urinary tract symptoms (LUTS) in the community-dwelling elderly population. However, there have been no urodynamic DU criteria universally applicable in daily practice and the lack of fundamental treatment to restore contractile function of detrusor muscle is an obstacle to establishing a standard strategy for the management of DU. In addition, there is a lack of research on the natural history of the disease and the characteristics of the use of each treatment method, which hinders the establishment of a comprehensive understanding of the disease. Previously, we investigated the prevalence and clinical features of idiopathic DU in the community-dwelling elderly aged over 65 years [1]. In the present study, a cohort of 327 elderly patients with idiopathic DU was followed up over 10 years to investigate the characteristics of the use of each treatment method for DU and urodynamic changes over time.
Study design, materials and methods
The cohort was prospectively followed up over 10 years with a pre-defined protocol which consists of periodic evaluations with International Prostate Symptom Score (IPSS), 3-day frequency-volume chart, free uroflowmetry, and measurement of post-void residual (PVR) volume. Urodynamic DU was defined as a bladder contractility index (BCI)＜100 for male patients and a maximum flow rate (Qmax)≤12 mL/s combined with a detrusor pressure at Qmax (PdetQmax) ≤10 cmH2O for female patients based on a pressure-flow study (PFS). Urodynamic evaluation was conducted repeatedly every 5 or 10 years and additionally after consultation with the patients when the patient's LUTS changed significantly during follow-up. The treatment methods applied to the patients in routine practice were classified into seven categories; medication for the decrease of bladder outlet resistance, endoscopic surgery on the prostate, cholinergics, clean intermittent catheterization, maintenance of indwelling catheter, medication for the improvement of storage symptoms, and observation without treatment. Treatment methods administered at 1 year and 10 years after DU diagnosis were compared, and LUTS, voiding efficacy, and urodynamic index including BCI in male patients and Qmax and PdetQmax in female patients were evaluated at baseline and 10 years after treatment.
Results
The average age of patients was 73.3 years, and 77.7% were male patients. BCI averaged 78.1 in male patients and PFS Qmax and PdetQmax averaged 10.2 mL/s and 7.9 cmH2O in female patients. At 10-year follow-up, evaluation on the treatment methods was performed in 206 (63.0%; male 158, female 48) patients. After 10 years, there was no significant difference in the rate of use of medication for the decrease of bladder outlet resistance, but the use of medication for storage symptoms, cholinergics, and clean intermittent catheterization tended to decrease. On the other hand, the number of observation cases increased significantly to 12.1% (Fig. 1). The storage and voiding score of the IPSS tended to deteriorate. Free Qmax also showed a tendency to decrease from 8.6 mL/s to 7.4 mL/s, and free PVR volume showed a significant deterioration from 78.2 mL to 122.3 mL. Among the patients who repeatedly underwent urodynamic study, BCI deteriorated significantly from 77.5 to 61.7 in male patients, but there were no significant differences in PFS Qmax and PdetQmax in female patients during follow-up.
Interpretation of results
Our study was conducted to improve understanding of natural history of idiopathic DU and to explore what treatment methods are used in actual clinical field. Medications for the decrease of bladder outlet resistance were used in more than 60% of the patients, and, for the same purpose, endoscopic surgery on the prostate was performed on 31% of male patients. Cholinergics were used in 10.9% of the patients during the first year, but its use tended to decrease to 5.1% after 10 years. Presumably, cholinergics may not be an effective medication for the management of idiopathic DU. One of notable findings among the use of treatment methods is that medications for storage symptoms were used in around 40% of the patients both in the first year and 10 years. The number of observation cases without treatment increased significantly from 4.4% to 12.1% and this may imply that there is a group who are reconciled to observation without treatment because all the treatment for idiopathic DU is ineffective. During the 10-year follow-up period, most of LUTS and voiding efficacy tended to deteriorate even though various treatment methods were applied. In particular, free PVR volume showed a significant deterioration over time. Moreover, a significant deterioration in BCI was observed in male patients, while there were no significant differences in PFS Qmax and PdetQmax in female patients during follow-up. Taken together, DU may be a disease condition that progresses slowly and worsens.