Dementia as a Risk Factor for Falls and Fall Injuries Among Nursing Home Residents

Carol van Doorn, PhD, Ann L. Gruber-Baldini, PhD, Sheryl Zimmerman, PhD, J. Richard Hebel, PhD, Cynthia L. Port, PhD, Mona Baumgarten, PhD, Charlene C. Quinn, PhD, George Taler, MD, Conrad May, MD, Jay Magaziner, PhD, MSHyg


J Am Geriatr Soc. 2003;51(9) 

In This Article


Person-time rates were used to describe the incidence of falls and injurious falls. Event rates and relative risks were derived from Poisson regression models. Numbers of falls and injurious falls were the dependent variables; an offset term in the model took into account the patient's length of follow-up. Fall risk factors served as the independent variables. Generalized estimating equations (GEEs) were used to account for clustering within nursing homes,[21] and an exchangeable covariance structure was used to model this dependence.

For the analyses focusing on dementia as the risk factor of primary interest, other variables were evaluated as potential confounders by the inclusion of each, one at a time, in the model with dementia. Those whose inclusion altered the relative risk of falls for dementia by 10% or more were regarded as confounders and were included in a multivariate model. The use of this change-in-estimate confounder selection procedure has been found to function well in simulation studies to protect against type 1 statistical error.[22]

Logistic regression was used to estimate the odds ratio of injury associated with dementia. Fall episodes were the units of analysis, and GEEs were fit to account for clustering within residents. All analyses were performed using the SAS and STATA statistical software packages (SAS Inc., Cary, NC, and STATA Corp., College Station, TX).


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