Background/Purpose: Comorbidity is highly prevalent in osteoarthritis (OA), although the origin of this is not well understood. The presence of multi-joint symptoms in OA, and noted associations between obesity and OA in non-weight bearing joints, suggests a likely systemic component. Lung disease has also has been associated with obesity and other systemic factors. Our purpose is to investigate the association between the extent of symptomatic joint involvement in patients with OA and prevalent lung disease.

Methods: Patients with end-stage hip and knee OA were recruited from an orthopaedic clinic in 2010-2012. Patient questionnaires captured symptomatic joints, comorbidities (lung disease, heart disease, diabetes, and high blood pressure), BMI (calculated from reported height and weight), smoking status, functional limitations (Western Ontario McMaster University OA Index physical function subscale) and demographic characteristics. Bivariate analysis tested trends in lung disease prevalence by symptomatic joint count categories (1; 2-4; and 5+). Logistic regression analyses evaluated the association between symptomatic joint count (continuous) and lung disease, adjusting for other assessed study measures.

Results: Study sample: 913 individuals scheduled for joint replacement surgery (469 knees and 444 hips). Mean age was 64 years, 44% male. Lung disease was reported by 9.5%. Mean symptomatic joint count was 4.4 (range: 1-20); almost 40% reported ≥5 symptomatic joints. Comparing individuals reporting lung disease with those who did not, those reporting lung disease had significantly higher mean BMI (mean ± SD: 33.2 ± 8.0 vs 29.4 ± 6.2); more previous/current smokers 41.4% vs 23.6%, greater comorbidity (significantly more with heart disease, diabetes, and high blood pressure), and greater symptomatic joint count (mean ± SD: 6.2 ± 4.4 vs 4.2 ± 3.2). A statistically significant increasing trend in lung disease prevalence was observed with joint count categories (1; 2-4; 5+). Logistic regression showed, adjusted for study covariates, each numerical increase in symptomatic joint count was associated with a 7% (OR: 1.07, 95% CI: 1.01, 1.14) increased odds of reporting lung disease. Other independent predictors of lung disease were previous/current smoker (OR: 2.64, 95% CI: 1.32, 4, 5.26), reporting diabetes (OR: 2.37, 95% CI: 1.28, 4.40) and having functional limitations (OR: 1.03, 95% CI: 1.01, 1.06). Females were significantly more likely to report lung disease (OR: 2.40, 95% CI: 1.34, 4.28). There were no significant associations with BMI, high blood pressure or surgical hip or knee group.

Conclusion: Findings suggest that having multi-joint symptoms in OA may increase the probability of concurrent lung disease. This raises questions for OA research including the nature of possible underlying mechanisms.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-between-extent-of-symptomatic-joint-involvement-in-osteoarthritis-and-comorbid-lung-disease-in-patients-scheduled-for-joint-replacement-surgery/