Patients with newly diagnosed ankylosing spondylitis (AS) are at a higher risk of developing obstructive sleep apnea (OSA), according to research results published in Frontiers in Medicine.
Investigators conducted a longitudinal, nationwide cohort study of patients with newly diagnosed AS in order to examine predisposition to subsequent OSA, which was not fully examined previously.
Researchers collected data from the Longitudinal Health Insurance Research Datasets of the Taiwan National Health Insurance program. They retrieved claim datasets from 1997 to 2013, which included information on outpatient visits, discharge records, and prescriptions.
The final cohort included 2210 patients with AS and 8840 healthy controls. Among the AS group, 79.14% of patients (64.62% men) were aged between 20 and 59 years. Patients were from a significantly lower proportion of low-income households and had longer hospital stays, but they had a higher proportion of comorbidities and medication use.
Using a univariate analysis model, investigators indicated a crude hazard ratio (HR) of 3.031 (95% CI, 1.888-4.865) of OSA among patients with AS. The adjusted HR (aHR), identified through multivariate modeling, was 2.794 (95% CI, 1.705-4.578). Significant risk factors included being men (aHR, 2.174), asthma (aHR, 2.371), esophageal disease (aHR, 2.469), and hepatitis B viral infection (aHR, 3.523).
Incidence rates of OSA were 7.54 and 22.84 per 100,000 person-months in the AS and control groups, respectively. Using 4 different proportional hazard models, researchers did not identify a large variance in the stability of the aHRs (range, 2.718-3.036).
According to the slope of Kaplan-Meier curves and a test for proportional risk assumption, investigators found that OSA risk in AS was time-dependent. At 0 to 24 months, the aHR was 7.919 and decreased to 1.816 at ≥24 months from the index date.
Age- and sex-stratified subgroup analyses indicated higher aHRs for women (4.533) and for patients aged >60 years (3.930).
Study limitations included a lack of information on potential confounding factors, including smoking status, which increases the risk for OSA, and a lack of information about the severity of AS or OSA diagnoses and a lack of relevant variables, including polysomnography results, image reports, physical examination findings, and disease activity information.
“Further studies are recommended to clarify the underlying [biologic] mechanisms of these associations [between AS and OSA],” the researchers concluded. “It is important to evaluate sleep quality and quantity for patients with AS to detect the occurrence of OSA and reduce further complications.”
Tsao C-H, Huang J-Y, Huang H-H, et al. Ankylosing spondylitis is associated with risk of new-onset obstructive sleep apnea: A nationwide population-based cohort study [published December 6, 2019]. Front Med. doi:10.3389/fmed.2019.00285