Contribution of individual diseases to death in older adults with multiple diseases

Abstract

Objectives: To determine empirically the diseases contributing most commonly and strongly to death in older adults, accounting for coexisting diseases.

Design: Longitudinal.

Setting: United States.

Participants: Twenty-two thousand eight hundred ninety Medicare Current Beneficiary Survey participants, a national representative sample of Medicare beneficiaries, enrolled during 2002 to 2006.

Measurements: Information on chronic and acute diseases was ascertained from Medicare claims data. Diseases contributing to death during follow-up were identified empirically using regression models for all diseases with a frequency of 1% or greater and hazard ratio for death of greater than 1. The additive contributions of these diseases, adjusting for coexisting diseases, were calculated using a longitudinal extension of average attributable fraction; 95% confidence intervals were estimated from bootstrapping.

Results: Fifteen diseases and acute events contributed significantly to death, together accounting for nearly 70% of death. Heart failure (20.0%), dementia (13.6%), chronic lower respiratory disease (12.4%), and pneumonia (5.3%) made the largest contributions to death. Cancer, including lung, colorectal, lymphoma, and head and neck, together contributed to 5.6% of death. Other diseases and events included acute kidney injury, stroke, septicemia, liver disease, myocardial infarction, and unintentional injuries.

Conclusion: The use of methods that focus on determining a single underlying cause may lead to underestimation of the extent of the contribution of some diseases such as dementia and respiratory disease to death in older adults and overestimation of the contribution of other diseases. Current conceptualization of a single underlying cause may not account adequately for the contribution to death of coexisting diseases that older adults experience.

Figure 1. The Proportional Contribution of Diseases to Death by an Empiric Method Among Older Adults According to Age and Gender

The proportional contribution of diseases to death among women and men and among individuals <80 years and 80+ years was determined empirically from claims data for the Medicare Current Beneficiary Survey 2002–2006 cohort using longitudinal extension of the average attributable fraction; 95% confidence intervals were estimated by generating 100 bootstrap samples. Abbreviations: AKI, acute kidney injury; MI, myocardial infarction * The disease contributed significantly to death only in one age group or gender.

Figure 1. The Proportional Contribution of Diseases to Death by an Empiric Method Among Older Adults According to Age and Gender

The proportional contribution of diseases to death among women and men and among individuals <80 years and 80+ years was determined empirically from claims data for the Medicare Current Beneficiary Survey 2002–2006 cohort using longitudinal extension of the average attributable fraction; 95% confidence intervals were estimated by generating 100 bootstrap samples. Abbreviations: AKI, acute kidney injury; MI, myocardial infarction * The disease contributed significantly to death only in one age group or gender.