Predicting excess cost for older inpatients with clinical complexity: A retrospective cohort study examining cognition, comorbidities and complications.

Hospital-acquired complications increase length of stay and contribute to poorer patient outcomes. Older adults are known to be at risk for four key hospital-acquired complications (pressure injuries, pneumonia, urinary tract infections and delirium). These complications have been identified as sensitive to nursing characteristics such as staffing levels and level of education. The cost of these complications compared to the cost of admission severity, dementia, other comorbidities or age has not been established.To investigate costs associated with nurse-sensitive hospital-acquired complications in an older patient population 157,178 overnight public hospital episodes for all patients over age 50 from one Australian state, 2006/07 were examined. A retrospective cohort study design with linear regression analysis provided modelling of length-of-stay costs. Explanatory variables included patient age, sex, comorbidities, admission severity, dementia status, surgical status and four complications. Extra costs were based on above-average length-of-stay for each patient's Diagnosis Related Group from hospital discharge data.For adults over 50 who have length of stay longer than average for their diagnostic condition, comorbid dementia predicts an extra cost of A$874, (US$1,247); any one of four key complications predicts A$812 (US$1,159); each increase in admission severity score predicts A$295 ($US421); each additional comorbidity predicts A$259 (US$370), and for each year of age above 50 predicts A$20 (US$29) (all estimates significant at p