Prior asthma exacerbations predict future risk
medwireNews: The risk for moderate or severe asthma exacerbations is primarily predicted by the occurrence of prior corresponding exacerbations, shows research.
The study, which monitored 330 patients with asthma at 4-monthly intervals for a year, assessed a number of different potentially predictive factors, including asthma severity, level of control, Asthma Control Test scores, atopic, functional, and inflammatory parameters, as well as exacerbation history.
But in multivariate analysis, previous severe exacerbation was the only factor that significantly predicted future severe exacerbations. Similarly, previous moderate exacerbation was the only factor that significantly predicted future moderate exacerbations.
In all, 193 (58.5%) patients experienced one or more moderate exacerbations during the 12 months of follow-up. The likelihood was increased 2.91-fold (p=0.001) for patients who had moderate exacerbations in the 4 months prior to baseline and 1.70-fold (p=0.008) for those with moderate exacerbations during the first 4 months of the study, compared with patients with no exacerbations.
The number of patients experiencing a severe exacerbation was much lower, at 27, or around 8%, and the researchers explain that this was due to the exclusion of patients whose baseline severity required more frequent follow-up than the 4-monthly schedule allowed. Indeed, the majority of patients, at more than 80%, had moderate or mild persistent asthma at baseline and so the team cautions that the findings should not be generalized to patients with more severe disease.
Nevertheless, multivariate analysis results were consistent with those of other studies, the researchers report, with previous severe exacerbations – in the 4 months prior to the start of the study and in the first 4 months of follow-up – significantly predicting future ones.
Francisco Javier Álvarez Gutiérrez (Hospital Universitario Virgen del Rocio, Seville, Spain) and colleagues highlight in BMC Pulmonary Medicine that a severe exacerbation between the baseline interview and the 4-month follow-up had the greatest effect, increasing the risk 6.89-fold (p=0.002).
“This, therefore, appears to be important not only in patients with severe asthma but also in patients with different levels of disease severity receiving treatment in outpatient clinics,” they observe.
A severe exacerbation in the 4 months prior to the study was associated with a 4.22-fold (p=0.005) increased risk of future severe exacerbations.
The team believes that “these results could reveal a particular [severe exacerbation] patient profile or phenotype, irrespective of other clinical, functional or inflammatory parameters.”
One other parameter that significantly predicted severe exacerbations was poor inhalation technique, which at the baseline visit predicted the occurrence of severe exacerbations, at an odds ratio of 4.22. But the researchers comment that this was “a solvable factor,” with the inhaler technique considered correct by the end of follow-up in 96% of patients, improving rates of controlled disease from 27% to 51%.
By Lucy Piper
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