INTRODUCTION

Obesity has emerged as a pervasive public health issue since the late 1980s. As of 2018, 42% of adults in the United States (US) had a body mass index (BMI) greater than or equal to 30 kg/m2.1 Obesity is commonly categorized by BMI into class I obesity (30.0-34.9 kg/m2), class II obesity (35.0-39.9 kg/m2), and class III obesity (≥40.0 kg/m2), reflecting increasing levels of obesity severity.2 Obesity is associated with a spectrum of chronic conditions including, but not limited to, chronic kidney disease (CKD), hypertension, coronary artery disease, heart failure, stroke, type 2 diabetes (T2D), and metabolic dysfunction-associated steatohepatitis (MASH).3,4 Obesity is also associated with increased rate of progression of these conditions and increased risk of all-cause mortality; each 5-unit increase in BMI is associated with a 31% rise in risk of premature death.5 From an economic perspective, obesity poses significant financial challenges, with the US healthcare system spending $260.6 billion in 2016 on obesity-related costs, which equates to around $2505 per person with obesity.6 Addressing obesity, therefore, has implications for both public health and healthcare spending.

The treatment landscape for obesity care is rapidly evolving, giving patients and providers more treatment options. The American Society for Metabolic and Bariatric Surgery now advises bariatric surgery for all patients with a BMI of 35 kg/m2 or more, regardless of other health conditions.7 Furthermore, the Food and Drug Administration has approved the use of three glucagon-like peptide-1 receptor agonists (GLP-1 RA) for chronic weight management.8 These medications are now options for patients with a BMI ≥30 kg/m2 or 27 ≥kg/m2 with a weight-related comorbidity like CKD or T2D. These new care options, characterized by improved safety and effectiveness compared to prior weight management treatments, mark a significant development in the way providers and patients manage obesity.

In turn, the payer landscape for managing obesity is rapidly evolving. As commercial and public insurers’ as well as employer coverage policies for these new obesity treatments evolve, there is a pressing need to explore the clinical and economic outcomes associated with these treatments. However, there are uncertainties surrounding the completeness and accuracy of documentation of obesity through International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) coding in medical claims, a common real-world data source fit-for-purpose for cost and outcome evaluations. Specifically, there is lack of clarity around how often and for whom obesity ICD-10-CM diagnosis codes are used in medical claims. This ambiguity impacts accurate obesity patient identification in claims databases. Consequently, this affects the ability to effectively study this population and to identify the full population of patients eligible for chronic weight loss interventions, like bariatric surgery and GLP-1 RAs. Therefore, this study aims to validate obesity diagnosis codes in medical claims data and determine the factors that influence their use.