The aging rate, proportion of elderly population among entire population, has been increasing globally, and the rate in Japan exceeded 28.1% in 2019. Urinary incontinence is regarded as one of the geriatric syndromes [1] and associated with multiple health related problems including dermatitis, falls, lower activity of daily living, impairment of dignity, and higher mortality. Double incontinence, urinary/anal incontinence, was highly prevalent in the nursing home setting [2], and significant predictors for time to developing double incontinence were preexisting urinary incontinence, greater functional or cognitive impairments, more comorbidities, older age, and lesser quality of nursing home care [3]. The aims of the present study were to investigate the prevalence of urinary incontinence, anal incontinence and double incontinence in the elderly aged 65 or older living in Japanese special elderly nursing homes nation-widely and identify the associated risk factors.

We recruited residents aged 65 and older living in special elderly nursing home since October 15th, 2015 to November 16th, 2015 from member facilities of the Japanese Council of Senior Citizens Welfare Service. We reviewed their information including age, gender, admission duration, Care-Needs level (1 (slightly impaired) to 5 (bed-ridden)), short memory and Barthel Index. We also checked fluid intake and dietary calorie. Definition of urinary incontinence and anal incontinence of the present study is any leakage of urine and feces.
Statistical analysis was performed using the JMP software, version 14.1.0 (SAS, Cary, NC). Kruskal-Wallis test was used to compare age, admission duration, Care-Needs level, Barthel Index, fluid intake and dietary calorie divided by continence status. Proportion of gender and short memory divided by continence status was analyzed by a chi-square test. We estimated odds ratios and 95% confidence interval to reveal risk factors for urinary incontinence, anal incontinence and double incontinence by using a logistic regression analysis. We put all parameters into multivariate analyses. P value of less than 0.05 was considered to be statistically significant.

We asked 2,341 member facilities registered in the Japanese Council of Senior Citizens Welfare Service to participate in the present study and 969 facilities responded to us. Total of 5,728 elderly residents aged 65 or older participated in the study. After careful exclusion of the subjects with insufficient data, finally 4,491 elderly persons (male 866 and female 3,625 persons) were enrolled for cross-sectional data analyses. Baseline characteristics divided by continence status were shown in Table 1. Venn diagram demonstrates continence status of the elderly (Figure 1); 12.3% of the residents were continent, 17.5% had urinary incontinence only, 4.2% had anal incontinence only and 65.9% had double incontinence. Overall prevalence of urinary incontinence and anal incontinence was 83.4% and 70.1%, respectively.
Multivariate analyses revealed age (Odds ratio (OR) [95% confidence interval (CI)], 1.018 [1.005 – 1.031]), Barthel Index (OR [95%CI], 0.960 [0.956 – 0.964]), impairment of short memory (OR [95%CI], 2.185 [1.788 – 2.670]) and dietary calorie for every 100 kcal increase (OR [95%CI], 1.091 [1.044 – 1.139]) were significant risk factors for urinary incontinence. As for anal incontinence, Barthel Index (OR [95%CI], 0.952 [0.948 – 0.955]), impairment of short memory (OR [95%CI], 2.492 [2.057 – 3.019]), fluid intake for every 100 ml increase (OR [95%CI] , 0.965 [0.943 – 0.988]) and dietary calorie  for every 100 kcal increase(OR [95%CI], 1.042 [1.004 – 1.082]) were significant risk factors. As for double incontinence, Barthel Index (OR [95%CI], 0.953 [0.950 – 0.957]), impairment of short memory (OR [95%CI], 2.536 [2.095 – 3.069]), fluid intake for every 100 ml increase (OR [95%CI], 0.971 [0.950 – 0.993]) and dietary calorie  for every 100 kcal increase(OR [95%CI], 1.057 [1.020 – 1.095]) were significant risk factors.

This is the first nation-wide survey of continence status conducted in the special elderly nursing home in Japan. Approximately two-thirds of elderly participants had double incontinence. Barthel Index and impairment of short memory were common risk factors for all types of incontinence. Dietary calorie was also a common risk factor; however, magnitude of effect was very low.

Prevalence of double incontinence among special elderly nursing home is very high. We need to care not only urinary incontinence but also anal incontinence. Urinary tract / gastrointestinal experts should deepen their understanding of each other's areas of expertise. Gathering wisdom to improve continence status, activity of daily living and quality of life of the frail elderly through a transdisciplinary approach is crucial issue in the globally aging society.

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