Hypothesis / aims of study
Some studies have estimated that in nursing homes more than 30 % of older residents take more than two anticholinergic drugs, and 5 % take more than five. Furthermore, an estimated 51 % of the general population use anticholinergic drugs. The Anticholinergic Cognitive Burden (ACB) scale is an index that classifies anticholinergic drugs with an anticholinergic effect (which may affect mortality and worsening cognitive function) into scores of 1 to 31. A one-point increase in the mean total daily ACB scale was associated with a 16% increased risk of cognitive impairment, and it increased the likelihood of inpatient admission by 11% and the number of outpatient visits2. An increased anticholinergic burden is also likely to affect bladder, defecation, and swallowing functions. Herein, we investigated the influences of the anticholinergic burden on the lower urinary tract functions of elderly subjects.
Study design, materials and methods
We analyzed the cases of elder-care facility residents whose bladder capacity were evaluated by abdominal ultrasonography or a Lilium α-200 Bladder Volume Ultrasound System (Lilium Otsuka Co., Sagamihara, Japan)3. Residents were excluded if they were unable to respond to various questionnaires such as frailty score, barthel index, IPSS, IPSS-QOL, and OABSS, had a prostate volume of ≥35 ml, or had an indwelling urethral catheter. For the residents who could urinate in a toilet, the voided volume and residual urine volume were measured three times, and the average values were calculated. For those who urinated in a diaper all day, the bladder capacity and residual urine volume were measured continuously for 24 hr with the Lilium α-200 because the urination time could not be identified. The nadir of the bladder capacity was defined as the residual urine volume, and the difference between the maximum bladder capacity and the nadir of the bladder capacity was defined as the voided volume. Furthemore, we divided residents into two groups depending on ACB score, and examined the difference of both groups with respect to voided volume, residual urine volume, and voiding efficacy. All statistical analyses were performed using IBM SPSS 28.0 （SPSS Inc., Chicago IL, USA）. Differences between the paired measurements were evaluated by paired t tests when distribution was normal, or by Mann - Whitney U tests otherwise. All tests were two-sided, with P<0.05 considered statistically significant.
Results
Of the 342 residents in four elder-care facilities, the evaluable cases were 202 residents (43 men, 159 women). The average age was 87.7 ± 7.1 years. The comorbidities were hypertension in 133, dementia in 119, stroke in 73, chronic heart failure in 68, and diabetes in 45 cases. Median frailty score is 3, barthel index is 35, IPSS is 5, IPSS-QOL is 5, and OABSS is 5. The mean values of voided volume, residual urine volume, and voiding efficiency were 140.8 ml, 109.5 ml, and 57.6%, respectively. Since the median ACB score was 2 points, we divided the residents into two groups: those with an ACB score ≤2 points (n=119) and those with ≥3 points (n=76). Among the comorbidities, percentage of patients with hypertension was significantly higher in the group with ACB ≥3 points than that with ≤2 points (77.6% vs. 52.9%; p=0.026). The mean value of residual urine volume was significantly higher (130.1 ml) in the ≥3-points group compared to 96.3 ml in the ≤2-points group (p=0.007). Voiding efficiency was significantly lower in the ≥3-points group than in the ≤2-points group (49.2% vs. 62.3%, respectively; p<0.001). However, no significant difference was found in average voided volume between the ≥3-points and ≤2-points groups (124.9 vs. 141.6 ml; p=0.265).
Interpretation of results
These results suggest that the long-term burden of drugs with anticholinergic effects in the elderly was associated with a decrease in voiding efficiency. Hypertension was more frequent in the group with ACB ≥3 points because many patients were taking drugs classified as ACB score 1, such as Nifedipine, Captopril, Triamterene, and Furosemide.