Comorbidities in Osteoarthritis: A Systematic Review and Meta-Analysis of Observational Studies

Objective: Osteoarthritis (OA) is a common chronic condition in older individuals, but its association with other chronic conditions is largely unknown. This study aimed to systematically review the literature on comorbidities in individuals with OA compared to those without. Methods: We searched 4 databases for observational studies on comorbidities in individuals with OA. Studies of OA only or in comparison with non-OA controls were included. The risk of bias and study quality were assessed using the Newcastle-Ottawa Scale. The prevalence of comorbidities in the OA group and the prevalence ratio (PR) and 95% confidence interval (95% CI) between OA and non-OA groups were calculated. Results: In all, 42 studies from 16 countries (27 case-only and 15 comparative studies) met the inclusion criteria. The mean age of participants varied from 51 to 76 years. The pooled prevalence of any comorbidity was 67% (95% CI 57–74) in individuals with OA versus 56% (95% CI 44–68) in individuals without OA. The pooled PR for any comorbidity was 1.21 (95% CI 1.02–1.45). The PR increased from 0.73 (95% CI 0.43–1.25) for 1 comorbidity to 1.58 (95% CI 1.03–2.42) for 2, and to 1.94 (95% CI 1.45–2.59) for ≥3 comorbidities. The key comorbidities associated with OA were stroke (PR 2.61 [95% CI 2.13–3.21]), peptic ulcer (PR 2.36 [95% CI 1.71–3.27]), and metabolic syndrome (PR 1.94 [95% CI 1.21–3.12]). Conclusion: Individuals with OA are more likely to have other chronic conditions. The association is dose-dependent in terms of the number of comorbidities, suggesting multimorbidities. Further studies on the causality of this association and clinical implications are needed.