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OBJECTIVE: Airflow obstruction is relatively uncommon in young adults, and may indicate potential for the development of progressive disease. The objective of the present study was to enumerate and characterize airflow obstruction in a random sample of Canadians aged 20 to 44 years.SETTING: The sample (n=2962) was drawn from six Canadian sites.DESIGN: A prevalence study using the European Community Respiratory Health Survey protocol was conducted. Airflow obstruction was assessed by spirometry. Bronchial responsiveness, skin reactivity to allergens and total serum immunoglobulin E were also measured. Logistic regression was used for analysis.RESULTS: Airflow obstruction was observed in 6.4% of the sample, not associated with sex or age. The risk of airflow obstruction increased in patients who had smoked and in patients who had lung trouble during childhood. Adjusted for smoking, the risk of airflow obstruction was elevated for subjects with past and current asthma, skin reactivity to allergens, elevated levels of total immunoglobulin E and bronchial hyper-responsiveness. Of the subjects with airflow obstruction, 21% were smokers with a history of asthma, 50% were smokers without asthma, 12% were nonsmokers with asthma and 17% were nonsmokers with no history of asthma. Bronchial hyper-responsiveness increased the prevalence of airflow obstruction in each of these groups.CONCLUSION: Smoking and asthma, jointly and individually, are major determinants of obstructive disorders in young adults. Bronchial hyper-responsiveness contributes to obstruction in both groups.

In this issue of the Canadian Respiratory Journal, Blais et al (pages 27 to 32) publish an interesting study of the use of inhaled steroids in chronic obstructive pulmonary disease (COPD). Using the Quebec provincial database from the years 1990 to 1996, they found that these medications were given to more and more patients during the period of the study, and that the patients tended to be sicker than those who were not given inhaled steroids: they saw more physicians, including specialists; took more bronchodilators; and had more exacerbations. This is the result that I would have predicted if asked and is therefore not surprising. What surprised me is the fact that patients did not continue to use inhaled steroids once they had been started on them; of those given these drugs for the first time, one-half stopped them after approximately 18 months, and after five years, approximately only 20% were still taking them. Further, as the number of patients given inhaled steroids increased, persistence decreased. What are we to make of this? One could argue that the dates covered by the study of Blais et al preceded the clinical trials (1) showing that inhaled steroids reduced exacerbations in COPD and that they were not prescribed with the conviction that present-day physicians would employ. On the other hand, it seems unlikely that COPD patients were given these medications as a temporary expedient; presumably, most prescriptions for inhaled steroids were for chronic maintenance therapy. It is therefore unlikely that the prescribing physicians told COPD patients to take the drugs until they felt better and then discontinue them. It is also possible that inhaled steroids were unique respiratory drugs in that they were expensive and that this impacted persistence negatively. Although these patients had provincial drug insurance coverage, it was probably on a reimbursement basis, as in Manitoba, and inhaled steroids presented a cash flow problem.

In this issue of the Canadian Respiratory Journal, Gulmez et al (pages 287-290) review the presentation, management and outcome of malignant mesothelioma in central Anatolia, Turkey. There is nothing particularly new about the disease here; it presents with chest pain, dyspnea and pleural effusion, is diagnosed by biopsy and has a miserable outcome whatever is done for it, just like malignant mesothelioma in Canada. Mesothelioma in Anatolia is unusual in that it is very common, with an approximately equal sex distribution, and frequently occurs in relatively young people. The reasons for this are not a mystery. Anatolia is a volcanic area; there is a lot of asbestos on or near the surface, and it is widely used as construction material, in painting, and as insulation (pages 287-290)! Asbestos related disease is due to environmental, not occupational exposure, and exposure is more intense and occurs at an earlier age than in Canada. Not only that, but some areas of Anatolia are rich in erionite, and people build homes in and on erionite-bearing rocks. Erionite is apparently something like asbestos but worse in terms of carcinogenicity (1), perhaps because its crystals have large surface areas, and areas with erionite have an even higher incidence of mesothelioma.

In this issue of the Canadian Respiratory Journal, Cowie et al (pages 555-558) make the startling claim that "inhaled corticosteroid therapy does not control asthma". This sounds crazy: if inhaled steroids don't control asthma, what does? It turns out not to be crazy. Cowie et al reported on the effectiveness of asthma control according to Canadian guidelines (1) in several large groups of asthmatics evaluated by cross-sectional, one-point-in-time questionnaires. They found that patients on inhaled steroids were less well-controlled than those who were not on inhaled steroids, and that there was a dose effect, in that the larger the dose of inhaled steroids the worse the control. There is, of course, a simple explanation for this; patients with hard-to-control asthma are likely to be prescribed inhaled steroids, and the harder the disease is to control, the higher the dose. However, these findings are compatible with inhaled steroids having a minor effect on asthma control, something that we do not believe (2). There are excellent data from clinical trials (3) that inhaled steroids work, and in population studies (4), their use is associated with improved survival.

In this issue of the Canadian Respiratory Journal, Bourbeau et al (pages 480-486) publish what could be loosely described as a validation of a French-Canadian translation of the Chronic Respiratory Questionnaire (CRQ) (1) and the St George's Respiratory Questionnaire (SGRQ) (2). They translated the questionnaires and went over them in detail until they were convinced that the questionnaires actually asked the questions that they were supposed to. They then administered them to two groups of chronic obstructive pulmonary disease (COPD) patients. One group had stable COPD and was tested twice with a two-week period between tests to examine test-retest reproducibility. The second group consisted of patients who either had an exacerbation of their COPD or who underwent rehabilitation for their disease. Both situations are associated with improvements in quality of life that should be detectable by the questionnaires. These results were compared with a third standard quality of life questionnaire. The results were very good. The questionnaire results met expectations: they were reproducible in stable patients and showed when patients improved. In psychometric terms, they were reliable and valid. I recommend the paper to people who are interested in developing and testing such instruments, both for the knowledge displayed by the authors and for the clarity of their presentation.

In this issue of the Canadian Respiratory Journal, Gutierrez et al (pages 414-424) present normal lung function values and prediction equations for white Canadians. They had six laboratories across the country each test approximately 100 volunteer, nonsmoking white adults (the target was 120 each), with appropriate variation in age and sex. Adequate representation of different ages and sex were obtained, although it appeared to be harder to recruit elderly men than elderly women. A full battery of tests was performed on each person. The equipment was not standardized and varied from centre to centre, and some centres performed slightly different tests than others; in other words, the study was done under field conditions. The results were analyzed for each centre and pooled to produce the Canadian model. This was compared with several similar models developed in Europe and the United States (1-5).

In this issue of the Canadian Respiratory Journal, LindenSmith et al (pages 111 to 116) present data that strongly suggest that patients who do not have asthma frequently acquire this diagnosis. They recruited 90 adults who thought that they had asthma and, in fact, had symptoms of asthma, and found that over 40% of them did not have objective evidence of the disease; of these, 43% were taking inhaled corticosteroids. Objective evidence was defined as demonstrable reversible airways obstruction, meaning spirometric response to inhaled bronchodilators, diurnal peak flow variability and/or methacholine responsiveness. Of these, methacholine response was by far the most important; in fact, a confirmed diagnosis amounted to symptoms plus methacholine sensitivity. The authors discussed possible reasons for lack of methacholine responsiveness in people who really have asthma, but were unconvinced that these were important confounders in their study and cited other studies that have also found that asthma is overdiagnosed.

In this issue of the Canadian Respiratory Journal, Demeter et al (pages 435-441) describe lung cancer outcomes in a recent Alberta cohort. Not much is new; outcomes are bad, not much better than they were when I was in medical school more than 40 years ago. This is a particularly sad state of affairs in view of the fact that lung cancer is a self-inflicted phenomenon related to smoking. Further, this has been known for 40 years, and only recently have lung cancer rates levelled off in men, though they have continued to increase in women.

BACKGROUND:Standard methods for population studies of asthma include surveying population samples using questionnaires and examining people in laboratories. These procedures are extremely expensive. It would be helpful if, at least for some purposes, they could be replaced by cheaper techniques with adequate validity. OBJECTIVES: To determine agreement between survey and database in regard to the prevalence of asthma.METHODS: Responses to survey questions about asthma symptoms in the past 12 months were linked to physician claims in the Manitoba Population Health Repository.RESULTS: The overall agreement was moderate (κ=0.45 to 0.50) and increased if two years of physician claims were studied (κ=0.55 to 0.59); studying additional years had no further effect on agreement. Sex and smoking did not significantly affect the kappa scores.CONCLUSIONS: There were several plausible reasons for discrepancies. Symptoms recorded on the survey were intrinsically different from those recorded for physician visits. Physicians also used other respiratory codes instead of asthma, and survey participants did not see a physician every year for asthma. The estimates of prevalence derived from the survey and the administrative database included two overlapping groups of people. In each, the diagnosis of asthma seems justifiable, although the agreement between the two groups was only moderate to substantial. Both methods are useful, although they are useful for different purposes. Health care utilization estimates may be particularly useful for studying trends over time.