Trends in Multimorbidity of Multiple Noncommunicable Diseases Among Adults in the United States, 1999-2016

Background: Multimorbidity of noncommunicable diseases (NCDs) has brought enormous challenges to public health and become the main medical burden since last century. However, changes in multimorbidity of multiple NCDs over time have not been well described in the United States. Methods: A serial, cross-sectional analysis of the US nationally representative data from the National Health and Nutrition Examination Survey (NHANES) was applied. 49,512 non-institutionalized US participants, who were 20 years and older, were involved in the study. Nine NHANES cycles were included (1999-2000 to 2015-2016), and the sample size per cycle ranged from 4,880 to 6,218. Findings: Data on 49,512 individuals were analyzed from 1999-2016 NHANES data, including 17,142 youths, 19,819 middle-aged and 12,551 elders. The overall estimated prevalence of multimorbidity of NCDs was 52.69% [95%CI: 49.14% to 56.22%] in the 2015-2016, where it was 24.82% [95%CI: 21.97% to 27.93%] in the youths, 59.68% [95%CI: 55.20% to 64.02%] in the middle-aged and 87.25% [95%CI: 83.66% to 90.14%] in the old, respectively. From 1999 to 2016, the trends of multimorbidity of NCDs increased among the whole population over time (difference, 10.05% [95%CI, 6.60% to 13.51%]; P for trend <0.001), especially in the old males (difference, 13.93% [95%CI, 3.75% to 24.11%]; P for trend <0.001) and old females (difference, 8.54% [95%CI, -0.54% to 17.61%]; P for trend = 0.004). The estimated prevalence of hypertension & hyperlipidemia was 21.09% [95%CI, 18.95% to 23.40%] in 2015-2016, which was the highest among all pairs of multimorbidity, and the trend was also increased from 1999 to 2016 (difference, 10.54% [95%CI, 7.88% to 13.20%]; P for trend <0.001). Besides, the estimated prevalence of multimorbidity in the middle-aged population whose annual household income lower than $25,000 was high and noteworthily increased (difference, 13.94% [95%CI, 6.82% to 21.06%]; P for trend <0.001). Interpretation: Among the US adults, multimorbidity of multiple NCDs generally remained high and increased from 1999 through 2016. Funding Statement: This work was supported by the Science and Technology Development Plan Project of Jilin Province, China (grant number: 20180418083FG), the Natural Science Foundation of Science and Technology Department of Jilin Province, China (grant number: 20180101129JC), the Outstanding Youth Foundation of Science and Technology Department of Jilin Province, China (grant number: 20170520049JH), the National Natural Science Foundation of China (grant number: 11301213 and 11571068), the Scientific Research Foundation of the Health Bureau of Jilin Province, China (grant number: 2011Z116) and the National Key Research and Development Program of China (grant number: 2016YFC1303800). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: The NHANES obtained approval from the National Center for Health Statistics Research Ethics Review Board, and participants provided written consent.