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Clinical characteristics of asthma in patients with Obstructive Sleep Apnea (Master thesis)

Χαδιά, Κωνσταντίνα/ Chadia, Konstantina

Obstructive Sleep Apnea (OSA) and asthma are two diseases with an increased prevalence in the general population and a significant impact on public health. Patients with OSA and asthma [alternative overlap syndrome (AOS)] share symptoms, risk factors and comorbidities suggesting the possible presence of common pathophysiological mechanisms between them. Aim Aim of the study was to record the clinical characteristics of asthma in patients with OSA in addition to their comorbidities, in order to reveal possible correlations between asthma control (number of exacerbations, ACT score) and OSA severity. Patients-Methods Patients fulfilling the diagnostic criteria for AOS were selected retrospectively from the records of the Sleep Unit of the Respiratory Medicine Department at the University General Hospital of Alexandroupolis. Patients’ data were collected regarding their anthropometric characteristics, their respiratory function, polysomnography data, as well as their comorbidities and asthma medication. Further analysis was also carried out according to the level of asthma control and the number of exacerbations, the asthma phenotype and the presence or absence of allergic rhinitis. Results. A total of 102 patients (53 men and 49 women) was finally included in the study. The mean age of the patients was 56.5 ± 12.8 years and almost all women (45/49) were postmenopausal. Severe OSA (AHI ≥ 30 episodes/sleep hour), moderate (AHI 15-29.9 episodes/sleep hour) and mild OSA (AHI 5-14.9 episodes/sleep hour) were observed in 49%, 27.5% and 23.5% of patients respectively. Arterial hypertension (66.7%), dyslipidemia (52%), diabetes mellitus (46.1%), allergic rhinitis (45.1%), hypothyroidism (40.4%) and GERD (29.4%) were the most frequent comorbidities recorded. Patients with AOS and allergic rhinitis had higher AHI (p = 0.043) and Charlson comorbidity index (p = 0.002). The majority of patients (55.9%) had moderate asthma control (ACT score 17.4 ± 0.9), while before CPAP treatment a negative correlation of ACT was observed with BMI (r = - 0.209, p = 0.035), AHI (r = -0.426, p < 0.001), oxygen desaturation index (r = -0.466, p < 0.001) and time with hemoglobin saturation <90% (r = -0.228, p = 0.021). Patients with asthma exacerbations (44/102) suffered more frequently from allergic rhinitis (p = 0.001) and presented with higher AHI (p = 0.022) and more severe disturbances of respiratory indices during sleep (ODI, p = 0.006; Aver SpO2%, p = 0.021; Min SpO2%, p = 0.031; T SpO2<90% p = 0.016). After treatment with CPAP, the ACT score was improved (p < 0.001) and higher scores were recorded in patients with good adherence to CPAP (p = 0.038). Also, a reduction in the number of patients who experienced an asthma exacerbation was noticed (p = 0.002). Among patients included in the study, 63 were characterized as T2 low asthma (33 men/30 women, mean age 57.3 ± 13.9 years) and 30 (20 men/19 women, mean age 55.6 ± 10.9 years) as T2 high. The mean eosinophil count for patients with T2 high phenotype was 160.5 ± 29.2 cells/μl. No statistically significant differences were recorded between the two asthma phenotypes in terms of anthropometric characteristics and OSA severity. After treatment with CPAP, an improvement in asthma control was observed in both groups, however, the patients with T2 high phenotype had a greater change in the ACT score (p = 0.027). Regarding asthma exacerbations, patients with T2 high phenotype had more frequent exacerbations compared to the group of patients with T2 low asthma (59% vs. 33.3%, p = 0.011), a difference that was alleviated after CPAP treatment. Conclusions OSA and asthma share common clinical features, comorbidities and risk factors that contribute to their bidirectional interaction. Both asthma control, exacerbations and allergic rhinitis were associated with OSA severity. The treatment with CPAP showed positive results in asthma control accompanied with a reduction in the number of asthma exacerbations in people with AOS. In addition, patients with OSA are more likely to present with a T2 low asthma phenotype, evidence that strengthens the hypothesis of altered inflammatory response of individuals with AOS.