Comorbid association of obstructive sleep apnea (OSA) and thrombotic primary antiphospholipid syndrome (tPAPS): A more severe phenotype?

Objective: We aimed to evaluate the frequency of obstructive sleep apnea (OSA) in patients with thrombotic primary antiphospholipid syndrome (tPAPS), to investigate the performance of screening tools for OSA in this scenario and to compare clinical/laboratorial differences in tPAPS patients with and without OSA.

Methods: We consecutively enrolled patients with tPAPS to undergo sleep studies using a portable monitor. OSA was defined as apnea-hypopnea index ≥15 events/h. Frequency of OSA in tPAPS was evaluated and compared with age-, gender-, and BMI-matched controls (1:3 ratio) from the Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil). Next, we tested the performance of three different screening tools for assessing OSA in patients with tPAPS. Finally, patients with tPAPS were stratified according to OSA status comparing their clinical and laboratory characteristics (including damage burden measured by Damage Index for Antiphospholipid Syndrome [DIAPS] and biomarkers associated with thrombosis) using standard statistical procedures.

Results: Fifty-two patients were included for analysis (females: 82.7%; mean age: 48 ± 14 years; body-mass index: 31.1 ± 6.5 Kg/m; 25% with moderate-severe OSA). When compared to matched controls from ELSA-Brasil (n = 115), there was no significant differences in the frequencies of OSA (tPAPS: 12/42 [28.6%] vs. controls: 35/115 [30.4%], p = 0.821). Among screening tools, NoSAS had the highest area under ROC curve (AUC 0.806, CI 95% 0.672-0.939, p = 0.001), followed by STOP-Bang (AUC 0.772, CI 95% 0.607-0.938, p = 0.004). Patients with comorbid tPAPS and OSA presented higher levels of von Willebrand factor (vWF) (median 38.9 vs. 32.6, p = 0.038) and DIAPS (median 5 vs. 2, p = 0.020), when compared to those without OSA. OSA remained statistically associated with higher DIAPS, even after controlling for age, disease duration and BMI.

Conclusion: OSA is common in patients with tPAPS, with rates comparable to a non-referred population. Both NoSAS and STOP-Bang scores seems to be useful for screening OSA in these patients. Patients with tPAPS+OSA had higher damage burden and higher levels of vWF, which might suggest a more severe phenotype of tPAPS in this scenario.