Asthmatics hospitalized during the H1N1 influenza pandemic had less-severe outcomes than did nonasthmatics, U.K. researchers have found.
People with asthma saw a lower risk of dying or requiring intensive care than did nonasthmatics, including people without any comorbidities. They were just as sick as nonasthmatics at admission. And the difference in outcomes could not be wholly ascribed to asthmatics’ use of inhaled steroids: Nonasthmatics taking inhaled steroids for other conditions did not see any protective effect.
A multivariate analysis showed asthma itself to be an independent factor for less-severe outcomes in patients hospitalized with H1N1.
This finding, from a prospective cohort of 1,520 people admitted to 75 different U.K. hospitals during the pandemic, was "surprising," said Dr. Malcolm Semple, the University of Liverpool, England, who presented his findings to the European Respiratory Society annual congress in Amsterdam.
However, it did align with recent results from a global analysis of 70,000 H1N1 patients, in which asthma was also seen to be associated with less severe outcomes (PLoS Med 2011;8:e1001053).
"Respiratory viruses cause exacerbations of asthma, and so it would be tempting to assume that these people were admitted with exacerbations of asthma – that they were less sick than the rest," Dr. Semple said in an interview. "But if anything, they were more sick, with more dyspnea and the same amount of radiological changes of pneumonia" as the other patients admitted to hospital.
"Do steroids protect everyone? No. But do steroids protect asthmatics? Emphatically, yes."
For their research, Dr. Semple and his colleagues used data from a prospective cohort in a study funded by the U.K. Department of Health during the H1N1 pandemic of 2009 and 2010. The cohort was used to provide real-time information on the pandemic and its clinical features to the Department of Health, and data collected were standardized to include information on age, comorbidities, inhaled steroid use, time from symptom onset to admission, and medications administered in hospital.
"It was something innovative that we had never tried before," Dr. Semple said of the cohort, adding that its large size "allowed us to catch this signal – it would be very hard to replicate this study in a non–pandemic situation."
The researchers found that the asthmatics, who comprised a quarter of the cohort (n = 385), were half as likely as nonasthmatics to die or require intensive care (11.2% vs. 19.8%; unadjusted odds ratio, 0.51) despite similar rates of pneumonia at admission.
Three variables – inhaled steroid use, admission within the first 4 days of symptoms, and systemic steroid use – were all seen as contributing to less severe outcomes for asthmatics. However, even after adjusting for these, simply having asthma was still associated with a 45% reduced likelihood of death or intensive care (adjusted OR, 0.55).
Asthmatics taking inhaled steroids were significantly less likely to die or require intensive care (7.4%) than were those not taking inhaled steroids (15.4%).
But inhaled steroids protected only the asthmatics in the study. About a fifth of the patients taking inhaled steroids were not taking them for asthma – and these patients saw no benefit, meaning that the findings do not support the use of inhaled corticosteroids in nonasthmatics.
"Do steroids protect everyone? No. But do steroids protect asthmatics? Emphatically, yes," Dr. Semple said. "The implication for practice is that, if you have a diagnosis of asthma, you should adhere to the published guidance if you’re a physician; and if you’re a patient, you should do as you’re told and take your steroids regularly."
Dr. Semple and his colleagues’ study was funded by the U.K. Department of Health. The researchers disclosed no conflicts of interest.