Multimorbidity and disability among elderly Medicare beneficiaries

BACKGROUND: Multi-morbidity, defined as the co-existence of two or more chronic conditions (either physical or mental illnesses)is very common. Although multimorbidity and disability are related, the effect of different types of multimorbidity on disability remains unknown.

OBJECTIVE: Examine the association between disability and multimorbidity among elderly.

METHODS: Cross-sectional data from the 2005 Medicare Current Beneficiary Survey, representing 29.3 million elderly. Chronic physical conditions (arthritis, cancer, diabetes, heart disease, hypertension, respiratory diseases, and osteoporosis) and any mental illnesses were derived from self-reports. Disability was based on self-reports on Activities of Daily Living (ADL) and Instrumental Activities of Daily Living. Multinomial logistic regressions were performed to analyze the relationship between multi-morbidity and disability after controlling for demographic and socioeconomic characteristics. We defined multi-morbidity into 4 groups: 1)concurrent presence of any physical and mental illness; 2)concurrent presence of two or more physical conditions; 3)no mental illness and only one physical illness; and 4) no chronic physical or mental illness.

FINDINGS: Overall, 12% had co-occurring medical and mental illnesses and 66% had multimorbidity in physical illnesses (i.e, 2 or more physical illnesses). Based on ADL scores, elderly with mental and physical conditions were three times as likely to have moderate disability and 1.6 times as likely to have severe disability compared to those with multimorbidity in physical illnesses.

CONCLUSION: Presence of mental illness is more disabling than concurrent presence of 2 or more physical illnesses. Health improvement efforts need to identify mental health disabilities and provide relief from mental illnesses in elderly.