Disparities in the burden and progression of multi-morbidity across adulthood

PROJECT SUMMARY
RELEVANCE: Approximately 1 in 4 U.S. adults suffers from multimorbidity, or two or more concurrent
chronic diseases. People with multimorbidity experience more disability and higher mortality risk and have
higher medical costs than people with 1 chronic condition. Our understanding of the onset and progression of
multimorbidity is limited. OBJECTIVES: To develop clinical practice guidelines and interventions, it is
necessary to have accurate information about the progression of multimorbidity, the age and timing of onset,
and differences in these across population groups. AIMS: 1) Harmonize and bridge national longitudinal data
to track the incidence of chronic diseases and multimorbidity in the U.S. starting at age 30. We will combine 7
premier national cohort datasets of adult health (Add Health, NLSY79, NLSY97, PSID, REGARDS, H-EPESE,
HRS) to create a synthetic nationally representative cohort of adults starting at age 30 years, compiling over 1.7
million person-years of follow-up and include sizeable number of racial/ethnic minorities. 2) Estimate the
progression to multimorbidity starting at age 30 years. We will identify the age-specific progression rate of
common chronic disease clusters and the sentinel conditions associated with higher risks of progression to
additional diseases. 3) Develop measures of age-specific risk of multimorbidity for the US adult population and
calculate the lifetime risk of developing multimorbidity and years spent with multimorbidity. 4) For major
race-ethnic, sex, economic, and geographic groups, identify the sentinel conditions, age-specific progression,
and lifetime risk of multimorbidity. We will estimate differences across groups and quantify the implications of
reducing these disparities on disease-free life expectancy, with the additional innovation of adjusting for biases
due to differential mortality and institutionalization. DESIGN: Bridging and reweighting procedures will be
applied to develop a new data infrastructure with nationally representative longitudinal birth cohorts and
synthetic cohorts. We will use Poisson regression to model the ages at which disparities in multi-morbidity
emerge. To capture the sequencing and pacing of multimorbidity, we will estimate the probability of
experiencing an additional (k+1th) condition for those with k prior chronic conditions. We will estimate
cumulative probabilities based on Kaplan-Meier survival probabilities. Disparities will be quantified using
Greenwood’s estimator. IMPACT: This project will advance understanding of the nature, onset, and
progression of multimorbidity. To inform clinical practice and healthcare guidelines, we will identify
conditional risks of transitioning to additional diseases given age of onset and sentinel disease. With particular
relevance to policy, we will model the years of disease-free life expectancy that would be gained by
interventions that delay or avert the onset of sentinel diseases. The data infrastructure generated from this
project will be made available to the research community and will be useful for a variety of aging-related
research questions.

Grant Number: 5R01AG074019-04
NIH Institute/Center: NIH
Principal Investigator: Solveig Argeseanu Cunningham