Prevalence of obesity-related multimorbidity and its health care costs among adults in the United States.

backgroundOverweight and obesity are associated with many obesity-related complications (ORCs) and drive increased health care costs. However, data on the impact of obesity severity on multimorbidity and the effect of multimorbidity on cost and health care resource utilization (HCRU) in people with overweight or obesity are limited.

objectiveTo determine in reference to obesity-related multimorbidity (1) if prevalence increases with higher levels of weight class, (2) if higher levels of weight class are associated with an increased risk of multimorbidity at an earlier age, and (3) how HCRU and health care costs are impacted, including if there is a beyond-additive effect on ORC-related costs.

methodsThis retrospective cross-sectional study used linked electronic health records (EHRs) and insurance claims from Optum's de-identified Market Clarity Data. Costs were considered from January 1 to December 31, 2019. Patients continuously insured in 2018 and 2019 with at least 1 recorded body mass index (BMI) in 2019 were included. The presence of 17 prespecified ORCs was determined from the database based on the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes. ORC-related medical services costs were based on ICD-10-CM diagnosis codes in the primary position; pharmacy costs were based on National Drug Codes. Total health care costs were the sum of medical services and pharmacy costs. Weight classes were derived from the patients' median BMI in the EHR in 2019.

resultsThe prevalence of multimorbidity increased with increasing weight levels (12.3% in overweight and 33.4% in class 3 obesity for ages 19-40 years; 41.5% and 66.6% for ages 41-65 years; and 70.6%-85.9% for age ≥65 years). Ages for predicted 50% risk of having at least 2 ORCs were 59, 54, 49, and 43 years among patients with overweight and obesity classes 1, 2, and 3, respectively. The mean effect of multimorbidity on ORC-related costs was beyond additive in those with obesity, such that the ORC-related costs were about $1,082 (151%), $1,696 (218%), and $2,433 (264%) for class 1, class 2, and class 3 obesity, respectively. This effect was not present for overweight, for which the cost was $310 (42%). Individuals with multimorbidity had higher odds of emergency department visits (odds ratio [OR] = 1.74; 95% CI = 1.73-1.76) and inpatient hospitalization (OR = 3.32; 95% CI = 3.27-3.38).

conclusionsThe prevalence of obesity-related multimorbidity increased with increasing weight classes within age groups. Obesity-related multimorbidity presented at an earlier age with higher weight class, such that the predicted probability of having obesity-related multimorbidity was more than a decade younger in class 2 and class 3 obesity compared with overweight. It was associated with increased HCRU and higher-than-expected costs exceeding the sum for the ORCs. Early diagnosis and treatment of obesity may be needed to prevent or delay the onset of obesity-related multimorbidity and limit its associated health care costs.