Metabolic-inflammatory phenotypes, osteoarthritis, and lower-extremity functional limitation in US adults: a NHANES 2007-2018 study.

INTRODUCTION

To identify metabolic-inflammatory profiles in US adults and assess their cross-sectional associations with self-reported osteoarthritis (OA) and lower-extremity functional limitation.

METHODS

We analyzed six National Health and Nutrition Examination Survey cycles from 2007-2008 to 2017-2018. Latent class analysis used body mass index, waist circumference, systolic blood pressure, diabetes, and log-transformed neutrophil-to-lymphocyte ratio. Survey-weighted logistic regression assessed prevalent OA in 9770 adults and lower-extremity functional limitation in 2189 adults with available Physical Functioning Questionnaire data.

RESULTS

Among 9770 participants, 559 met the study definition of OA. Three profiles were identified: relatively healthy, intermediate metabolic, and highest metabolic-inflammatory burden. After full adjustment, the intermediate profile was not associated with OA (OR 1.34, 95% CI 0.93-1.95), whereas the highest-burden profile was associated with higher odds of OA (OR 1.76, 95% CI 1.34-2.32). Among 2189 participants with functional data, 1239 had functional limitation; the highest-burden profile was associated with this outcome (OR 3.25, 95% CI 2.39-4.41). Seven-indicator and leave-one-adiposity-indicator-out analyses retained positive associations for the highest-burden profile, although class distributions and intermediate-profile estimates varied.

CONCLUSIONS

The highest-burden profile was associated with prevalent self-reported OA and lower-extremity functional limitation in this nationally representative cross-sectional sample. These findings do not establish temporality or causality. Prospective studies with joint-specific OA ascertainment are needed to determine whether combined systemic risk profiling can inform prevention, rehabilitation, or risk stratification. Key Points • NHANES data identified three metabolic-inflammatory profiles among US adults. • The profile with the highest combined systemic burden was associated with prevalent self-reported osteoarthritis. • The same profile was associated with lower-extremity functional limitation among 2,189 participants with available questionnaire data. • The cross-sectional design precludes causal inference; longitudinal, joint-specific validation is required.