Differences in the Measurement of Comorbidities Based on ICD-10-CM Coding Definitions Using Medicare Advantage...

Area of Science:

• Gerontology
• Health Services Research
• Biostatistics

Background:

• Medicare Advantage (MA) encounter data, available since 2019, presents opportunities for research.
• Concerns regarding the quality and consistency of MA encounter data persist.
• Understanding comorbidity coding in MA versus traditional Fee-For-Service (FFS) is crucial for accurate health research.

Purpose of the Study:

• To evaluate the consistency of International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) comorbidity coding between Medicare Advantage (MA) and Fee-For-Service (FFS) data.
• To assess the reliability of MA encounter data for research purposes by comparing it with FFS claims data.

Main Methods:

• Utilized data from the National Health and Aging Trends Study (NHATS) linked with Medicare enrollment, MA encounter, and FFS claims (2016-2017).
• Included participants with continuous enrollment in MA or FFS for one year prior to the study.
• Identified comorbidities using ICD-10-CM codes and estimated prevalence differences (PDs) after standardizing demographic and clinical covariates.

Main Results:

• After standardization, comorbidity prevalence was largely similar between MA and FFS beneficiaries.
• Peripheral vascular disorder and renal failure were more prevalent in MA beneficiaries.
• Fluid/electrolyte disorders and deficiency anemias showed higher prevalence in FFS beneficiaries, with other differences being minor.

Conclusions:

• Comorbidity prevalence is largely consistent between MA encounters and FFS claims, supporting MA data reliability for aging research.
• Observed discrepancies may stem from true differences or variations in coding practices influenced by provider incentives and documentation.
• Further validation studies are recommended to address remaining coding discrepancies.