Comorbidity Subgroups Among Medicare Beneficiaries Seeking Health Care for Musculoskeletal Pain.

Background: Treatment of musculoskeletal pain in older adults may be more effective if it incorporates integrated management of comorbid health conditions. The purpose of this study was to define empirically derived comorbidity subgroups among Medicare beneficiaries with an index condition of osteoarthritis (OA) or low back pain (LBP) as a precursor to the development of comorbidity-specific pain treatment pathways.

Methods: This study included Medicare beneficiaries participating in the Medicare Current Beneficiary Survey (MCBS) and seeking care for OA (n = 723) or LBP (n = 617) with data available for 3 years after entry into the survey. We identified 30 comorbidity diagnoses using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnostic codes in claims data during beneficiaries' first year in the survey. Latent class analysis defined comorbidity subgroups, and posterior probabilities were used to assign subgroup classification. Self-reported disability was compared over three consecutive years for each subgroup.

Results: We identified similar comorbidity subgroups for OA and LBP. The subgroups included (range of percent prevalence) low comorbidity (47.6%-54.4%), nonvascular (21.8%-28.6%), diabetes (12.2%-15.0%), renal disease with complicated hypertension (5.5%-5.8%), and complex cardiac disease/high comorbidity (3.3%-5.8%). OA and LBP subgroups with more complex comorbidity burden generally demonstrated higher disability over 3 years.

Conclusions: Five comorbidity subgroups were identified, with a large proportion of older adults classified into the subgroup defined by a low probability of most comorbidities. These findings provide direction for the development of pain treatment pathways that are tailored to address common comorbidity profiles among older adults.