The ACB (anticholinergic cognitive burden) score is an index that classifies 115 types of drugs with an anticholinergic effect (which may affect cognitive function) into scores of 1 to 3. A one-point increase in the mean total daily ACB score 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 visits. 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.

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). Residents were excluded if they were unable to respond to various questionnaires (Frailty index, 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. Furthemore, we divided residents into two groups depending on ACB score, and compared voided volume, residual urine volume, and voiding efficacy between two groups. All statistical analyses were performed using IBM SPSS 26.0 （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.

Of the 211 residents in four elder-care facilities, the evaluable cases were 155 residents (27 men, 128 women). We excluded the 22 residents with an indwelling urethral catheter, four with benign prostatic hyperplasia, and 23 who could not respond to various questionnaires. The average age was 88.4 ± 6.9 years. The comorbidities were dementia in 115, hypertension in 96, stroke in 61, chronic heart failure in 57, and diabetes in 38 cases. The mean Frailty index is 2.1 ± 1.1, Barthel index 43.0 ± 29.9, IPSS 9.2 ± 8.4, IPSS-QOL 2.6 ± 1.5, and OABSS 5.1 ± 3.9. Abdominal ultrasonography was performed in 26 residents, and the Lilium α-200 was used in 129 residents. Forty-five out of 129 residents were measured continuously for 24hr. The mean values of voided volume, residual urine volume, and voiding efficiency were 141.2 ± 90.0ml, 109.1 ± 95.0ml, and 57.6 ± 21.0%, respectively. Since the average ACB score was 2.2 ± 0.15 points, we divided the residents into two groups; those with ACB score ≤2 points (n = 92) and with ≥3 points (n = 63). Among the comorbidities, number of patients with hypertension was significantly higher in the group with ACB ≥3 points than that with ≤2 points (49 vs. 47; p = 0.006). The mean value of residual urine volume was significantly higher (130.9 ± 95.9ml) in the ≥3-points group compared to 94.0 ± 91.8ml in the ≤2-points group (p = 0.007). Voiding efficiency was significantly lower in the ≥3-points group than in the ≤2-points group (51.2 ± 21.5 vs. 62.4 ± 19.4%, respectively; p = 0.000). However, no significant difference was found in average voided volume between the ≥3-points and ≤2-points groups (136.2 ± 86.9 vs. 144.7 ± 92.5ml; p = 0.584).

These results suggest that the long-term burden of drugs with anticholinergic effects in the elderly was associated with a decrease in voiding efficiency, caused by an increase in residual urine volume. 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.

Clinicians must keep in mind that the anticholinergic burden already increases the residual urine volume and reduces the voiding efficiency of elderly individuals.

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