Prevalence of asthma-like symptoms with ageing

Abstract

Background: Change in the prevalence of asthma-like symptoms in populations of ageing adults is likely to be influenced by smoking, asthma treatment and atopy.

Methods: The European Community Respiratory Health Survey collected information on prevalent asthma-like symptoms from representative samples of adults aged 20-44 years (29 centres in 13 European countries and Australia) at baseline and 10 and 20 years later (n=7844). Net changes in symptom prevalence were determined using generalised estimating equations (accounting for non-response through inverse probability weighting), followed by meta-analysis of centre level estimates.

Findings: Over 20 years the prevalence of 'wheeze' and 'wheeze in the absence of a cold' decreased (-2.4%, 95% CI -3.5 to -1.3%; -1.5%, 95% CI -2.4 to -0.6%, respectively) but the prevalence of asthma attacks, use of asthma medication and hay fever/nasal allergies increased (0.6%, 95% CI 0.1 to 1.11; 3.6%, 95% CI 3.0 to 4.2; 2.7%, 95% CI 1.7 to 3.7). Changes were similar in the first 10 years compared with the second 10 years, except for hay fever/nasal allergies (increase seen in the first 10 years only). Decreases in these wheeze-related symptoms were largely seen in the group who gave up smoking, and were seen in those who reported hay fever/nasal allergies at baseline.

Interpretation: European adults born between 1946 and 1970 have, over the last 20 years, experienced less wheeze, although they were more likely to report asthma attacks, use of asthma medication and hay fever. Decrease in wheeze is largely attributable to smoking cessation, rather than improved treatment of asthma. It may also be influenced by reductions in atopy with ageing.

Keywords: Asthma Epidemiology.

Figure 1

Study flow diagram for participants in the ECRHS III Canada (6) and Poland (1) not included—first data submitted after 1995. Note that ECRHS included follow-up of non-random sample of those selected because they had symptoms—this group is not included in this analysis. ECRHS, European Community Respiratory Health Survey.

Figure 2

Net change in prevalence (%) of ‘current use of asthma medication’ (prevalence at ECRHS III minus prevalence at ECRHS I) adjusted for non-response and estimated by generalised estimating equations No estimate for Melbourne, Australia or Basel, Switzerland, as information on asthma medication use was not recorded during postal survey. ECRHS, European Community Respiratory Health Survey.

Figure 3

Comparison of change in prevalence in first 10 years to change in prevalence in second 10 years of follow-up (ie, ECRHS III-II change in prevalence minus ECRHS II-I change in prevalence) for all symptoms: adjusted for non-response and estimated by generalised estimating equations. ECRHS, European Community Respiratory Health Survey.

Figure 4

Net change in prevalence (%) of ‘current smoking’ (prevalence at ECRHS III minus prevalence at ECRHS I); adjusted for non-response and estimated by generalised estimating equations in each centre. ECRHS, European Community Respiratory Health Survey.

Figure 5

Net change in prevalence (%) of symptoms (prevalence at ECRHS III minus prevalence at ECRHS I); adjusted for non-response and estimated by generalised estimating equations stratified by smoking history. Some differences in numbers of countries for each analysis occur as information on smoking history in some centres differed. ECRHS, European Community Respiratory Health Survey.

Figure 6

Net change in prevalence (%) of symptoms (prevalence at ECRHS III minus prevalence at ECRHS I); adjusted for non-response and estimated by generalised estimating equations stratified by use of asthma medication. ECRHS, European Community Respiratory Health Survey.