Multimorbidity and Functional Limitations Among Adults 65 or Older, NHANES 2005-2012

Abstract

Introduction: The development of functional limitations among adults aged 65 or older has profound effects on individual and population resources. Improved understanding of the relationship between functional limitations and co-occurring chronic diseases (multimorbidity) is an emerging area of interest. The objective of this study was to investigate the association between multimorbidity and functional limitations among community-dwelling adults 65 or older in the United States and explore factors that modify this association.

Methods: We conducted a cross-sectional analysis of adults aged 65 or older using data from the National Health and Nutrition Examination Survey (NHANES) from 2005 through 2012. We used negative binomial regression to estimate the association between multimorbidity (≥2 concurrent diseases) and functional limitations and to determine whether the association differed by sex or age.

Results: The prevalence of multimorbidity in this population was 67% (95% confidence interval [CI], 65%-68%). Each additional chronic condition was associated with an increase in the number of functional limitations, and the association was stronger among those aged 75 or older than among those aged 65 to 74. For those aged 65 to 74, each additional chronic condition was associated with 1.35 (95% CI, 1.27-1.43) times the number of functional limitations for men and 1.62 times (95% CI, 1.31-2.02) the number of functional limitations for women. For those 75 or older, the associations increased to 1.71 (95% CI, 1.35-2.16) for men and 2.06 (95% CI, 1.51-2.81) for women for each additional chronic condition.

Conclusion: Multimorbidity was associated with increases in functional limitations, and the associations were stronger among women than among men and among adults aged 75 or older than among those aged 65 to 74. These findings underscore the importance of addressing age and sex differences when formulating prevention strategies.

Figure 1

Predicted mean number of limitations by the number of chronic conditions, stratified by sex and age group, National Health and Nutrition Examination Survey 2005–2012, for all 19 limitations and for ADL and IADL (7 limitations) only. Negative binomial regression was used to estimate the association between multimorbidity and functional limitation, adjusted for age, body mass index, and smoking. Abbreviations: ADL, activities of daily living; IADL, instrumental activities of daily living. [Table: see text]

Figure 2

Prevalence of 9 chronic conditions, by age and sex, among adults aged ≥65, National Health and Nutrition Examination Survey, 2005–2012. For pairwise comparisons of prevalence between sexes in each age group and between age groups of each sex, we found the following significant differences using a Bonferroni-corrected P value of <.001: between sexes in both age groups for CVD and arthritis; between women’s age groups for CVD; between women’s age groups for stroke and hypertension; between men’s age group for cancer. Error bars are 95% confidence intervals. Abbreviations: CKD, chronic kidney disease; CVD, cardiovascular disease. [Table: see text]

Figure

Prevalence among older adults of having difficulty performing 19 activities, by age group, National Health and Nutrition Examination Survey (NHANES), 2005–2012. The list of activities was derived from 19 NHANES questionnaire items, grouped into 5 domains, used to assess functional status. Responses to each question were dichotomized as either having no difficulty or having difficulty (some difficulty, much difficulty, or “unable to do”). For example, if the prevalence among adults aged 65 to 74 of having difficulty getting in and out of bed was 11%, then the prevalence of not having difficulty was 89%. [Table: see text]