Obstructive sleep apnea in patients with rheumatoid arthritis: Correlation with disease activity and pulmonary function tests

Aim of the workTo assess obstructive sleep apnea (OSA) as one of the common primary sleep disorders in patients with rheumatoid arthritis (RA) and study its correlation to disease activity and pulmonary function tests.Patients and methodsThis study included 30 female patients with RA who fulfilled the American College of Rheumatology/European league against rheumatism classification criteria. All the patients were subjected to full medical history, thorough clinical examination with evaluation of the disease activity using disease activity score-28 (DAS28), laboratory assessment of highly sensitive C-reactive protein (hsCRP), pulmonary function tests (PFTs) (FVC, FEV1 and FEV1/FVC) and one night polysomnography at the sleep laboratory.ResultsPolysomnographic data revealed OSA in 14 RA patients (46.7%). Patients with OSA showed longer disease duration (7.0 ± 1.94 years), higher BMI (30.8 ± 2.48), hsCRP level (6.7 ± 0.6 mg/L) and DAS28 (4.9 ± 1.85) than patients with no OSA (4.0 ± 1.72 years, 20.3 ± 1.55, 4.9 ± 0.3 mg/L and 3.7 ± 1.28 respectively). There was non-significant difference between both groups regarding the PFTs (p > 0.05). The study showed a significant correlation between AHI (apnea-hypopnea index) and BMI, hsCRP and DAS28 (r = 0.45, 0.43 and 0.51, respectively) (p < 0.05). No significant correlation was detected between AHI and PFTs.ConclusionObstructive sleep apnea is commonly associated with RA patients; these findings possibly suggest common underlying pathological mechanisms which may be linked to chronic inflammation. Co-existence of OSA in RA patients may influence the disease activity and the level of circulating inflammatory markers. Considering diagnosis and treatment of this sleep disorder in RA patients may help in improved clinical care, better prognosis and avoid rheumatoid-associated morbidities.