Mortality-related factors and 1-year survival in nursing home residents

Abstract

Objectives: To identify factors associated with 1-year mortality in newly admitted and long-stay (in nursing home longer than 1 year) nursing home residents by linking Minimum Data Set (MDS) information with data from the National Death Index and use these factors to create a useful tool for estimating risk levels for 1-year mortality.

Design: Retrospective cohort study with development and validation cohorts.

Setting: All 643 Medicare and Medicaid certified nursing homes in New York State during the study period.

Participants: The study included data on residents collected during full MDS assessments from June 1994 through December 1997. A total of 100,669 nursing home residents met the inclusion criteria for the newly admitted resident analysis. The newly admitted development cohort included 60,341 residents, and the newly admitted validation cohort included 40,328 residents. A total of 36,125 nursing home residents met inclusion criteria for the long-stay (residing in nursing home>1 year) cohort. The long-stay development cohort included 22,749 residents, and the long-stay validation cohort included 15,068 residents.

Measurements: The analytical approach was similar for the newly admitted and long-stay resident cohorts. Resident characteristics that were considered potential risk factors for mortality were examined individually in bivariate proportional hazards models, and factors with P <.05 were entered into a proportional hazards regression stepwise model. The strongest factors based on their chi-square values were selected for entry into a multivariate proportional hazards analysis. Hazard ratios (HRs), 95% confidence intervals, and P-values were derived from this model. A mortality risk index score was created for each resident by summing the value of each HR in the multivariate model for those who had the risk factor. A sensitivity analysis was performed to determine the effect of residents with an unknown death status. A similar analysis was performed on the validation cohort to validate the original results.

Results: Major factors associated with 1-year mortality were identified in both the newly admitted and long-stay cohorts. In both newly admitted and long-stay residents, a higher mortality risk index score was associated with increased 1-year mortality in both the development and validation cohorts.

Conclusions: MDS data can identify major factors associated with 1-year mortality in newly admitted and long-stay nursing home residents. These factors can be used to stratify residents into risk categories for 1-year mortality. This information could be important to residents, their families, and their physicians when developing care plans, as well as to agencies interested in healthcare resource planning.