Characteristics and outcomes of asthmatic outpatients with COVID-19 who receive home telesurveillance

Discussion

In a large French cohort of patients from the Greater Paris area receiving initial ambulatory care and home monitoring with a telesurveillance solution for COVID-19, asthma was independently associated with clinical worsening, but no asthmatic died within the 30-day follow-up.

Asthmatic patients accounted for 12.8% of this cohort total population, whereas the prevalence of asthma in France has been recently reported at 6.4% [11]. Although it might reflect a higher risk of SARS-CoV-2 infection among asthmatic patients, several factors must be taken into consideration when interpreting this finding. Firstly, we found an over-representation of women in the entire cohort (which is consistent with better healthcare programmes adherence in women, as previously described [12]); since asthma is more frequently diagnosed in adult women [13], this unbalanced sex ratio may contribute to overestimate its prevalence. Likewise, we can assume that asthmatic patients were more likely to accept registration on a home-monitoring telesurveillance solution than patients without respiratory comorbidity [14]. Consistent with our results, the study from Chhiba et al. [15] found that 14% of 1526 COVID-19 outpatients were asthmatic; the mortality rate was low in these patients and did not differ significantly from the non-asthmatic patients.

In the present study, asthma was independently associated with clinical worsening, which was not found in a previous study describing factors associated with clinical worsening among COVID-19 outpatients managed with the Covidom telesurveillance solution [10]. In the present work we included more patients and reached statistical significance, which could be clinically relevant, but could also have enhanced some bias. Indeed, in the context of real-life settings we cannot exclude overdiagnosis of asthma, as already reported in industrialised countries [14] and among obese patients [16]. As defined in the Global Initiative for Asthma (GINA) report [17], the diagnosis of asthma should be based on both history of variable respiratory symptoms and evidence of airflow limitation. In this large cohort, we were not able to verify that those criteria were obtained for each individual, and self-reported comorbidities might have resulted in misdiagnoses (i.e., misclassification of asthma by respondants). We can also hypothesise that asthmatic patients are more likely to report symptoms, which may precipitate hospitalisation. Given the real-life setting of our study, COVID-19 was clinically diagnosed by a physician, regardless of the positivity of RT-PCR. Despite the fact that COVID-19 was a major cause of viral symptoms in the Greater Paris area during the study period (March 2020–April 2021), diagnostic errors cannot be excluded. Notably, similar results were obtained in the subset of patients with available and positive RT-PCR. Other conditions associated with COVID-19-related clinical worsening can masquerade as asthma (such as cardiac insufficiency or COPD) [17], which would impact our main outcome. In the study of Choi et al. [7], asthma was not an independent risk factor for the clinical outcomes of COVID-19 after adjustment. Other authors emphasised the prognostic impact of asthma control during the previous year in COVID-19 patients, reporting an increase in COVID-19-related mortality in asthmatic patients who experienced an exacerbation within 1 year [18, 19]. As highlighted elsewhere, chronic use of systemic corticosteroids is an independent risk factor for worse COVID-19 severity and all-cause mortality in asthmatic patients infected with SARS-CoV-2 [20]. Of note, we did not observe any deaths in our study of 4276 asthmatic patients with COVID-19.

Alerts were more often triggered by asthmatic patients; however only a few led to EMS call. We found that asthmatic patients were more prone to experiencing respiratory symptoms such as cough and shortness of breath. Symptoms of asthma exacerbation may overlap with those of COVID-19, and the distinction between those two clinical presentations might be difficult. Thus, the proportion of alerts related to asthma worsening remains uncertain. We can speculate it was low and some respiratory discomfort might be due to anxiety and dysfunctional breathing disorders, which are notably more frequent in asthmatic women [21] and prevalent among post-COVID-19 patients [22–26]. In a subset of 61 patients with accessible medical records, we found that SARS-CoV-2 pneumonia was the main cause for hospitalisation. Only three patients (5%) required admission in an intensive care unit, and the only patient diagnosed with an asthma exacerbation had a quick recovery. Moreover, we did not find an over-representation of severe asthmatic patients treated with biologics. The presence of other comorbidities such as obesity is probably a crucial element that determines the prognosis of asthmatic patients infected with SARS-COV-2 [5, 27, 28]. Findings also suggest that the risk of SARS-CoV-2 infection and disease severity depends on asthma phenotype and may be reduced by Th2-high inflammation [29]. Several hypotheses have been proposed to explain the limited impact of asthma on COVID-19-related outcomes: lower bronchial expression of ACE2 viral receptor in asthmatic patients, protective role of bronchial mucus, advantageous immune profile and better compliance with medical recommendations during the COVID-19 pandemic (social distancing, hand washing, use of mask, etc.) [30]. There is also moderate evidence for a protective role of inhaled corticosteroids [31], which was not analysed in our study because this information was not systematically collected. In addition, we can hypothesise that careful telesurveillance with the Covidom solution had beneficial effects on asthma control, as previously described with other home-monitoring devices [32]. The Covidom solution does not allow self-monitoring of lung function using mobile spirometry at home, as previously described by others [33]. This might be a relevant option, as long as enhanced coaching and education by video and telemedicine can be provided [34].

In conclusion, asthma appeared independently associated with clinical worsening in outpatients receiving ambulatory care for COVID-19 using the Covidom telesurveillance solution for home monitoring, but no death was reported among asthmatic patients. These results may reflect an increased risk of COVID-19-related clinical worsening among asthmatic patients, but we cannot exclude underlying epidemiological biases inherent to this particular population in our convenience sample (i.e., patients who were more likely to get medical attention and over-interpret symptoms). Further research is needed to investigate the potential benefits of home monitoring among asthmatic patients during the COVID-19 pandemic.