Asthma diagnosis and treatment
Prognostic factors of asthma severity: A 9-year international prospective cohort study

https://doi.org/10.1016/j.jaci.2006.03.019Get rights and content

Background

The natural history of asthma severity is poorly known.

Objective

To investigate prognostic factors of asthma severity.

Methods

All current patients with asthma identified in 1991 to 1993 in the European Community Respiratory Health Survey were followed up, and their severity was assessed in 2002 by using the Global Initiative for Asthma categorization (n = 856). Asthma severity (remittent, intermittent, mild, moderate, severe) was related to potential determinants evaluated at baseline and during the follow-up by a multinomial logistic model, using the intermittent group as the reference category for relative risk ratios (RRRs).

Results

Asthma severity measured at baseline was a determinant of a patient's severity at the end of the follow-up. At baseline, severe persistent had a poorer FEV1% predicted, a poorer symptom control, higher IgE levels (RRR, 2.06; 95% CI, 1.38-3.06), and a higher prevalence of chronic cough/mucus hypersecretion (RRR, 4.90; 95% CI, 2.18-11.02) than patients with intermittent asthma. Moderate persistent showed the same prognostic factors as severe persistent, even if the associations were weaker. Mild persistent had a distribution of prognostic factors that was similar to patients with intermittent asthma, although the former showed a poorer symptom control than the latter. Remission mainly occurred in patients with less severe asthma and was negatively associated with a change in body mass index (RRR, 0.86; 95% CI, 0.75-0.97). Allergic rhinitis, smoking, and respiratory infections in childhood were not associated with asthma severity.

Conclusion

Patients with moderate and severe persistent asthma are characterized by early deterioration of lung function. High IgE levels and persistent cough/mucus hypersecretion are strong markers of moderate/severe asthma, which seems to be a different phenotype from mild persistent or intermittent asthma.

Clinical implications

Our results suggest that the evolution of asthma severity is to a large extent predictable.

Section snippets

Study design

The ECRHS is an international multicenter study of asthma. The first survey7 was performed in 1991 to 1993 on random samples of adults age 20 to 44 years. Each participant was sent a brief questionnaire (stage 1), and from subjects who responded, a 20% random sample was invited to undergo a more detailed clinical examination (stage 2). In addition, a symptomatic sample consisting of subjects who reported symptoms of waking with shortness of breath, asthma attacks, or using asthma medication in

Severity of asthma at the end of the follow-up (1999-2001)

At baseline (1991-1993), the mean age of the 856 patients with asthma included in the analysis was 34 years (SD, 7) and the average duration of the disease was 17 years (SD, 11). Nine years later (at the end of the follow-up), 102 (11.9%) were in remission (no symptoms, no exacerbations, no asthma medications in the last year), and 388 (45.3%) had intermittent, 69 (8.1%) mild persistent, 143 (16.7%) moderate persistent, and 154 (18.0%) severe persistent asthma.

Symptom control, lung function, and use of ICSs at baseline (1991-1993)

Patients with asthma in remission

Discussion

Asthma severity was prospectively investigated by using the GINA classification, which consists of a 3-dimensional score based on symptoms, lung function, and medication use.

The main findings of our analysis are as follows:

  • The deterioration of lung function plays a central role in predicting moderate/severe asthma, whereas the level of symptom control can help in predicting the probability of remission and whether asthma is going to be intermittent or persistent (mild, moderate, or severe)

  • The

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    The coordination of the European Community Respiratory Health Survey II was supported by the European Commission as part of their Quality of Life program.

    Disclosure of potential conflict of interest: R. De Marco has received reimbursement travel expenses from GlaxoSmithKline. The rest of the authors have declared that they have no conflict of interest.

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