Showing papers by "Pierre Ernst published in 1996"

Canadian Asthma Consensus Conference Summary of Recommendations

Abstract: The Asthma Committee of the Canadian Thoracic Society invited a group of Canadian physicians with a particular interest in asthma to meet in Montebello, Quebec, March 9-12, 1995 to arrive at a consensus statement on the optimal approach to the management of asthma in the pediatric and adult ambulatory care settings. The societies and associations represented are listed in the appendix with the names of the contributors to this document. The objectives of the Montebello conference were: 1. To review the current ambulatory care management of asthma in Canada; 2. To develop guidelines with the participation of family physicians and specialists; 3. To develop guidelines which are evidence-based; 4. In creating evidence-based guidelines to focus attention on aspects of asthma management that are currently not supported by randomized controlled trials; 5. To develop strategies that allow for the implementation of rational guidelines at a local level. Recommendations were based on a critical review of the scientific literature by small groups prior to the meeting and are categorized according to the strength of the scientific evidence supporting each recommendation (Table 1).

Bronchodilators and Acute Cardiac Death

Abstract: Bronchodilators used in the treatment of airway disease have been shown to have a variety of cardiac effects that may contribute to the occurrence of life-threatening events such as cardiac arrhythmias and cardiac arrest. We investigated whether theophylline and beta-agonists were associated with cardiovascular mortality among a cohort of subjects prescribed antiasthma medications. We used a population-based cohort of 12,301 subjects aged 5 to 54 yr, formed from health-insurance data bases from Saskatchewan, Canada, and spanning the period 1978 to 1987. Within this cohort, we identified all 30 deaths from cardiovascular causes in which acute asthma did not appear to be a contributing factor. We identified all asthma and cardiovascular drugs dispensed to these subjects shortly before their deaths and compared this therapy to that dispensed to a random sample of 4,080 person-time controls. After adjustment for age and the prior use of cardiac drugs, the rate of cardiovascular death was greater in users of theophylline, with a rate ratio (RR) of 2.7 (95% Cl:1.2 to 6.1), and in users of beta-agonists taken orally or by nebulizer (RR = 2.4; 95% Cl:1.0 to 5.4), but not in users of beta-agonists administered by metered-dose inhaler (RR = 1.2; 95% Cl:0.5 to 2.7). The great majority of cardiovascular deaths occurred among subjects with clinical or pathologic evidence of potentially lethal conditions. These results suggest that the use of theophylline and of beta-agonists administered orally or by nebulization should be avoided in subjects with significant cardiac disease or at high risk for such disease, especially acute coronary insufficiency and congestive cardiomyopathy. On the other hand, the use of beta-agonists administered by metered-dose inhalers (MDIs) was not associated with an increased risk of cardiovascular death.

Confounding by Indication and Channeling over Time: The Risks of β2-Agonists

Abstract: A previously published nested case-control study, the Saskatchewan Asthma Epidemiologic Project (SAEP) spanning 1980-1987, investigated the risk of fatal or near fatal asthma and found different risks for two inhaled beta 2-agonists, fenoterol and salbutamol. The authors assessed whether this comparison was confounded by indication because of channeling of inhaled fenoterol to more severely afflicted asthmatics. Using three subcohorts selected from a cohort of 12,301 asthmatics assembled from the computerized databases of Saskatchewan Health and followed over 7 years, the authors studied two forms of channeling and investigated whether greater asthma severity and less well-controlled disease were associated with preferential prescribing of a first prescription of inhaled fenoterol, as opposed to inhaled salbutamol, and whether they were associated with the likelihood of a switch from inhaled salbutamol to fenoterol as well as a switch from inhaled fenoterol to salbutamol. The authors found that the initial choice between fenoterol and salbutamol was independent of the severity of the asthma and disease control, but that preferential prescribing of fenoterol occurred among users of salbutamol who showed signs of increased severity or uncontrolled asthma. The switch from inhaled fenoterol to salbutamol was, however, minimally related to asthma severity. They conclude that the comparison between inhaled fenoterol and salbutamol in the SAEP may have been biased by indication. This study demonstrates that long-term information on medication use is essential to ensure that the results of such case-control studies are not biased by indication.

Increased morbidity and mortality related to asthma among asthmatic patients who use major tranquillisers.

Abstract: Objective: To assess the potentially increased risk of death or near death from asthma in asthmatic patients with psychosis. Design: Case-control study. Setting: The computerised health databases of the Canadian province of Saskatchewan. Subjects: 131 cases of death or near death from asthma identified within a cohort of asthmatic patients; 3930 matched non-cases. Exposure and outcome measures: The exposure of interest was the use of major tranquillisers in the period before an outcome event. Outcomes included death or near death from asthma. Results: Crude analyses showed that asthmatic patients who had used major tranquillisers in the previous 12 months were at a 3.2 (95% confidence interval 1.4 to 7.5) times greater risk of death or near death from asthma than asthmatic patients who did not use major tranquillisers. Past users of major tranquillisers who had recently discontinued use were at a particularly high risk (relative risk 6.6; 2.5 to 17.6). Adjustment for use of antiasthma drugs and other confounders abolished this excess risk. Conclusions: Asthmatic patients who use major tranquillisers seem to be at an increased risk of death or near death from asthma. Physicians treating asthmatic patients with a history of use of major tranquillisers should exercise greater caution with regard to management of such patients. Key messages Key messages Past users of major tranquillisers who have recently discontinued use are at particularly high risk Physicians treating asthmatic patients should consider a history of use of major tranquillisers as a marker for identifying patients at higher risk for the serious complications of asthma

Socioeconomic status and lung function among primary school children in Canada

Abstract: We examined the relationship of lung function level to socioeconomic status (SES) using a cross-sectional design among 989 primary school children selected from 18 Montreal schools and studied between April 1990 and November 1992. Information on each child's health, demographics, home exposure to tobacco smoke, pets, and cooking and heating fuel used in the child's home was collected by questionnaire. Spirometry was performed at school. Parental occupation was used to establish SES. After adjusting for personal, familial, and environmental factors, in boys but not in girls, FEV1 and FVC were progressively larger in higher categories of SES (p < 0.001 for linear trend). After taking into account the effect of multiple comparisons and adjusting for personal, familial, and environmental factors, boys from families in the lowest category of SES were found to have an FEV1 lower by 8.2% (95% CI, -13.8 to -2.1) and an FVC lower by 8.1% (95% CI, -13.4 to -2.6) when compared with the most advantaged. These results...

Usual dietary salt intake and asthma in children: a case-control study.

Abstract: BACKGROUND: A decline in host resistance due to an alteration in diet--primarily of salt--was recently put forward as a possible explanation for rising rates of asthma. METHODS: A case-control study was conducted in participants in a prevalence survey which included 187 children with asthma (defined by prior diagnosis and/or a decline in forced expiratory volume in one second (FEV1) of > or = 10% after exercise) and 145 age and sex matched controls. Subjects were selected from 989 children aged 5-13 years attending 18 elementary schools on the island of Montreal. Usual dietary salt intake was estimated from a food frequency questionnaire administered to the mother, and a salt intake score was used to group the children into quartiles from I (lowest) to IV (highest salt intake). Bronchial hyperresponsiveness to methacholine was assessed by Yan's method. Cases and controls were combined in one group to examine the relationship of salt intake to bronchial hyperresponsiveness to methacholine. Methacholine responsiveness was expressed as a dose-response slope and ranks of dose-response slopes were used in the analysis. RESULTS: After accounting for important confounding variables, there was no association between asthma and salt intake, while methacholine dose-response slope ranks increased with increasing salt intake and methacholine responsiveness was greater in the highest quartile than in the lowest quartile of salt intake. The median dose-response slopes in % fall in FEV1 per mumol methacholine for quartiles I, II, III, and IV were 5.4, 5.9, 7.7, and 8.7. CONCLUSIONS: No association was found between asthma or exercise-induced bronchospasm and dietary salt intake. Bronchial hyperresponsiveness to methacholine did, however, appear to increase with greater salt intake, but the relevance of this association to asthma is unclear.

Antiallergic and antitussive medications: extent of use and relationship to asthma exacerbations.

Abstract: Introduction : Les asthmatiques utilisent frequemment des produits antiallergiques ou antitussifs, en plus de leur traitement respiratoire. Ces produits interferent avec des mecanismes inflammatoires communs a toutes les allergies, et pourraient donc avoir des effets sur l'asthme. Objectifs : Investiguer les liens entre l'usage de produits antiallergiques et antitussifs et la survenue d'une aggravation de l'asthme ; etudier le niveau d'utilisation de ces produits chez les patients asthmatiques. Methodes : Les utilisateurs reguliers de produits antiasthmatiques ont ete identifies dans une base de donnees medicamenteuse. Une cohorte de patients a ete composee a partir de criteres d'âge et d'utilisation. Une etude cas-temoin a ete realisee au sein de la cohorte : le resultat a ete defini comme un nouvel usage de corticoides oraux, et une comparaison a ete faite entre cas et temoins apparies quant a l'utilisation de produits antiallergiques. Des odds ratios ont ete calcules par regression logistique, et ajustes en fonction de marqueurs de severite pour l'asthme. Resultats : 680 patients asthmatiques ont ete suivis dans la cohorte pour une duree moyenne de 1.390 jours. Les produits antitussifs, les antihistaminiques et les corticoides nasaux ont ete utilises par respectivement 40, 30 et 13 pour cent des patients. 134 paires cas-temoins ont ete construites : parmi ces patients, l'usage de produits antitussifs etait significativement lie a la survenue d'un asthme, avec un OR de 3.1. La relation avait une signification limite pour les antihistaminiques, et n'etait pas significative pour les corticoides nasaux. Ces resultats n'ont pas ete affectes par un ajustement en fonction de la severite de l'asthme. Conclusions : Cette etude confirme que les antitussifs et les antihistaminiques sont frequemment utilises par les patients asthmatiques, et indique que l'usage de ces deux classes de produits est lie a la survenue d'une frequence accrue d'aggravation de l'asthme, sans qu'il soit possible d'affirmer si cette relation est causale. Les corticoides nasaux sont d'usage moins frequent, et leur usage ne semble pas lie a la survenue d'une aggravation de l'asthme. Les effets des antihistaminiques et des antitussifs devraient etre mieux etudies chez les patients asthmatiques.

Socioeconomic Status and Childhood Atopy

Abstract: BACKGROUND: Variation in the prevalence of allergic disorders among socioeconomic groups could be due either to differences in the type of allergens encountered or to actual differences in susceptibility to sensitization to any particular antigen.