Vaccination is the most effective prevention of the severe course of COVID-19 (even in mutated strains of SARS-CoV-2).6,7 Acceptance of vaccination recommendations varies among different patient groups, and most developed countries have reached vaccination coverage above 70%.6 In general, it seems reasonable to expect better acceptance of vaccination in people with good health care adherence in other areas. If left untreated, OSA carries an increased risk of potentially life-threatening illnesses. It has been suggested to be associated with hypertension, heart rhythm disorders, ischemic heart disease, stroke, traffic accidents and premature death.8–16 Positive airway pressure (PAP) therapy remains the standard treatment in OSA, especially in patients with moderate to severe sleep apnea.17 Achieving adequate long-term compliance with positive airway pressure therapy is often problematic. In most studies, an average use of CPAP for more than 4 hours a night is considered adequate. However, this amount of CPAP use may only significantly affect OSA symptoms, with even better adherence to CPAP (up to 6 h nightly) required to reduce cardiovascular morbidity and mortality.18–22 The COVID pandemic has changed every part of our lives. There is clear evidence that it also changed the behavior of patients, including CPAP patients. Most studies found that in people with good adherence to CPAP, its use improved even more, and many people with previously inadequate CPAP use had improved compliance.23,24 On the other hand, data on the acceptance of vaccination in patients with SAA are not available. Furthermore, the impact of CPAP adherence and vaccination on the risk of severe COVID courses is also unknown. The study aimed to compare OSA patients who were adherent to CPAP therapy and OSA patients who refused any type of treatment (CPAP, surgery or other) in relation to: The cases were as follows:

Methods

This study is prospective. Patients were enrolled from 2005 to 2012 and followed for more than ten years at routine visits.

The inclusion criteria

Exclusion criteria

Contraindications for CPAP therapy. Indication for other treatment methods (BPAP, oxygen therapy, surgical treatment). Dominant etiology of central apnea. Use of drugs or substances associated with a high incidence of central apnea (especially alcohol abuse and opioid medication). Conditions associated with a high frequency of central apnea (especially recent history of stroke and decompensated heart failure).

The course of study

Sleep monitoring was performed with respiratory sleep polygraphy (Stardust, Easyscreen). each recording lasted at least 6 hours and was evaluated by sleep laboratory technicians according to the current American Academy of Sleep Medicine scoring manual.25 At the initial examination, the patient’s medical history was obtained. Daytime symptoms (ie, sleepiness and presence of microsleeps) have been assessed based on patient statements and the Epworth sleepiness score. The optimal therapeutic pressure was titrated using automatic CPAP for at least three consecutive nights during which the patient was hospitalized in the sleep laboratory. Subjects who agreed to use CPAP therapy at home were followed up further. The first check was done after three months of CPAP use. In this audit, the effect of CPAP therapy (measured by residual AHI), mean CPAP use per night, and Epworth sleepiness scale score were assessed. Annual follow-up was performed regularly for ten years with the same objective measures as at the first check-up. Individuals with adequate compliance over the past ten years (with an average CPAP use of more than 4 hours or more) and a residual AHI below 10% of pretreatment values ​​or below five at the first check-up were classified into group A. Individuals with a significant change in weight were excluded as this may alter the severity of OSA and reduce or increase risk for the course of COVID-19. Subjects who refused CPAP therapy at baseline or shortly after initiation of home therapy were observed longitudinally (group B). COVID-19 infection and vaccination data were obtained from the national registry from February 1, 2022 to February 7, 2022.

Retrospective exclusion criteria

Significant change in the patient’s body weight (more than 10% of the body weight at the start of treatment). Ineffectiveness of CPAP therapy (residual AHI higher than 10% of pre-treatment values ​​or higher than 5). Technical problems with CPAP therapy (especially problems with data collection or mask application). Poor CPAP compliance (less than 4 hours of CPAP use per average night). Death of the subject during follow-up from a cause other than COVID-19 by FEBRUARY 1, 2022.

Statistical analysis

Qualitative data were described using absolute numbers and relative frequency. The Shapiro-Wilk test was used to assess the normality of the distribution of values. Differences between study groups were assessed using Fischer’s exact test. Between-group differences in ordinal data were assessed using the Mann-Whitney U-test. Shapiro–Wilks normality tests indicated that quantitative data, except for circumferences (neck, waist, and waist/hip ratio), were normally distributed. The Mann-Whitney test assessed parameters with a non-normal distribution, and a two-tailed t test assessed parameters with a normal distribution. Forward Stepwise (Likelihood Ratio) logistic regression analysis was used to determine the significant factors affecting the overall risk of severe COVID-19. All tests were performed at an alpha level of 0.05. The statistical software used for the calculations was IBM SPSS Statistics for Windows, version 23.0. Armonk, NY: IBM Corp.

Informed consent was obtained from all individual participants included in the study.

Ethical Approval

All procedures performed in studies involving human participants followed the ethical standards of the ethics committee of the Bavarian Medical Association (approval number: 08064) and the 1964 Declaration of Helsinki and its subsequent amendments or comparable ethical standards. The local Ethics Committee of Olomouc University Hospital approved the study (decision number EC 98/21, date of issue June 7, 2021).

Results

From 2005 to 2012, our sleep laboratory consecutively examined 670 subjects with suspected sleep-disordered breathing. Of these, 405 were diagnosed with sleep apnea syndrome with an indication for CPAP therapy. In 278, CPAP therapy was initiated following the standard procedures reported. One hundred sixty-seven patients reached a mean compliance level of 4 hours per night and were classified into group A. In group A the mean number of hours of CPAP use last year was 6.98 ± 1.41 per night (min 4.14, max 11.1 ). One hundred and eleven subjects met one or more of the exclusion or retrospective criteria defined in the methods. Of those, 24 died from causes other than COVID-19 (20 of them before the COVID-19 pandemic even started). Forty-five subjects did not reach an adequate level of compliance and eighteen subjects had low efficacy of CPAP therapy. Only a small number of patients presented other reasons for exclusion (total, 24 subjects – indicated for other treatment modalities, eg, BPAP, surgical treatment or significant change in body weight). These patients were not eligible for any study group. One hundred and six rejected treatment early or shortly after starting home treatment. This group is designated as group B. More men were in group A (77.8% vs. 66% in group B). Age between study groups did not differ significantly (64.7 ± 10.6 vs. 65.9 ± 12.3). Similarly, BMI was comparable between groups (33.9 ± 6.1 vs. 34.08 ± 7.0). In anthropometric parameters, only differences were found in neck circumference, which was higher in the CPAP adherent group (43.6 ± 4.1 vs. 42.0 ± 4.4, p < 0.01). There were more non-smokers in group A (60% vs. 50.9%). All parameters of OSA severity (AHI, ODI, t90 and mean saturation) were worse/more severe in group A at baseline. Similarly, the symptoms of SAA, especially the ESS level, were significantly higher in group A. However, the total number of comorbidities was higher in the non-adherent group. Notably, the presence of pulmonary fibrosis was significantly higher in the nonadherent group. We analyzed our patient records and found that…