Identification of risk factors and development of a multivariable prognostic prediction model for incontinence-associated dermatitis in older nursing home residents

Incontinence-associated dermatitis (IAD) is an inflammatory skin condition caused by prolonged exposure of the skin to urine and feces. It is common among older adults in long-term care and contributes to pain, discomfort, and increased risk for secondary infection. This study aimed to identify risk factors for IAD development and to construct a prognostic model for incontinent nursing home residents aged ≥ 65 years. A secondary analysis was conducted using data from a cluster-randomized controlled clinical trial performed in Berlin, Germany (April 2019 to June 2021). A total of 149 incontinent residents were included. At week 12, 20 residents (13.4%) newly developed IAD. The final cluster-adjusted multivariable model identified lower Barthel Index scores, severe mobility impairment, and the absence of xerosis on the legs as significant predictors. An interaction between double incontinence and Barthel Index scores indicated that the protective effect of higher functional independence was reduced in residents with double incontinence. The model demonstrated good discrimination (area under the curve 0.82), sensitivity of 78.6%, specificity of 74.2%, and satisfactory calibration (Hosmer-Lemeshow test p = 0.67). These findings support early risk identification and targeted prevention; validation in a prospective cohort is warranted to confirm the model's robustness and clinical utility.