Incidence, Prevalence, and Risk for Urinary Incontinence for People with Dementia in the Community in Aotearoa New Zealand: An interRAI Study

Objectives

To identify 1-year period prevalence, 5-year incidence rate, and risks for urinary incontinence (UI) for people living with dementia.

Design

Retrospective cohort study.

Setting and Participants

Participants completed an International Residential Assessment Instrument Home Care (interRAI-HC) assessment in a 5-year period between August 1, 2016 and July 31, 2021 in Aotearoa New Zealand (N = 109,964).

Methods

For prevalence analysis, a dementia cohort was selected for a 1-year period from August 1, 2020 to July 31, 2021 (n = 7775). For incidence analysis, participants in the dementia cohort were followed from the first dementia diagnosis during the 5-year period. Dementia was identified by combining diagnoses of “Alzheimer's disease” and “Dementia other than Alzheimer's disease.” Participants were coded with UI if they were infrequently, occasionally, or frequently incontinent or if continence was managed with catheter/ostomy. Univariate and multivariate logistic regression analyses identified risk factors predicting UI onset. Cox regression analysis compared survival curves (months without UI) of the dementia and non-dementia cohorts, adjusting for variables significantly associated with incident UI in either cohort.

Results

The 1-year period (August 1, 2020 to July 31, 2021) prevalence of UI was 50.1% among people with dementia. The 5-year incident UI rate was 30.2 per 100 person-years for the dementia cohort and 24.5 per 100 person-years for the non-dementia cohort. Parkinson's disease posed the greatest risk of UI in both cohorts [dementia cohort odds ratio (OR), 3.0; 95% CI, 2.1–4.2; non-dementia cohort OR, 1.7; 95% CI, 1.4–2.0]. Controlling for risk factors, the hazard ratio for UI was 1.4 for people with dementia.

Conclusions and Implications

UI affects a significant proportion of people with dementia in Aotearoa New Zealand. Health professionals should directly ask about UI and consider living arrangements and comorbidities for people with dementia. Data-driven insights from interRAI-HC can guide resource allocation and service planning.