Air pollution, aeroallergens and cardiorespiratory emergency department visits in Saint John, Canada.

Existing studies of the association between air pollution, aeroallergens and emergency department (ED) visits have generally examined the effects of a few pollutants or aeroallergens on individual conditions such as asthma or chronic obstructive pulmonary disease. In this study, we considered a wide variety of respiratory and cardiac conditions and an extensive set of pollutants and aeroallergens, and utilized prospectively collected information on possible effect modifiers which would not normally be available from purely administrative data. The association between air pollution, aeroallergens and cardiorespiratory ED visits (n = 19,821) was examined for the period 1992 to 1996 using generalized additive models. ED visit, air pollution and aeroallergen time series were prefiltered using LOESS smoothers to minimize temporal confounding, and a parsimonious model was constructed to control for confounding by weather and day of week. Multipollutant and multi-aeroallergen models were constructed using stepwise procedures and sensitivity analyses were conducted by season, diagnosis, and selected individual characteristics or effect modifiers. In single-pollutant models, positive effects of all pollutants but NO2 and COH were observed on asthma visits, and positive effects on all respiratory diagnosis groups were observed for O3, SO2, PM10, PM2.5, and SO4(2-). Among cardiac conditions, only dysrhythmia visits were positively associated with all measures of particulate matter. In the final year-round multipollutant models, a 20.9% increase in cardiac ED visits was attributed to the combination of O3 (16.0%, 95% CI 2.8-30.9) and SO2 (4.9%, 95%CI 1.7-8.2) at the mean concentration of each pollutant. In the final multipollutant model for respiratory visits, O3 accounted for 3.9% of visits (95% CI 0.8-7.2), and SO2 for 3.7% (95% CI 1.5-6.0), whereas a weak, negative association was observed with NO2. In multi-aeroallergen models of warm season asthma ED visits, Ascomycetes, Alternaria and small round fungal spores accounted for 4.5% (95% CI 1.8-7.4), 4.7% (95% CI 1.0-8.6) and 3.0% (95% CI 0.8-5.1), respectively, of visits at their mean concentrations, and these effects were not sensitive to adjustment for air pollution effects. In conclusion, we observed a significant influence of the air pollution mix on cardiac and respiratory ED visits. Although in single-pollutant models, positive associations were noted between ED visits and some measures of particulate matter, in multipollutant models, pollutant gases, particularly ozone, exhibited more consistent effects. Aeroallergens were also significantly associated with warm season asthma ED visits.

The costs of cardiorespiratory disease episodes in a study of emergency department use.

OBJECTIVE: The average per person direct cost of illness of cardiorespiratory disease episodes was estimated based on a prospective study of emergency department visits. METHODS: Economic modelling of health care costs using prospectively collected resource utilization data (9/1/94 to 8/31/95) from hospital emergency department visitors assigned a diagnosis of asthma, chronic obstructive pulmonary disease (COPD), respiratory infections or cardiac conditions. RESULTS: The total direct costs (1997 CDN$) [95% C.I.] per patient were $1,043.55 [$922.65, $1,164.47] for asthma, $1,690.11 [$1,276.92, $2,103.30] for COPD, $676.50 [$574.46, $778.54] for respiratory infections, and $3,318.74 [$2,937.72, $3,699.76] for cardiac conditions. CONCLUSIONS: This study showed that on average, patients diagnosed with a cardiac condition had the highest total direct cost. Hospitalization cost was the largest component of costs for all diagnoses except asthma, for which medications were the single largest component of direct costs.

Beyond administrative data: characterizing cardiorespiratory disease episodes among patients visiting the emergency department.

We attempted to address deficiencies in administrative health service data during a study of cardiorespiratory emergency department visits. From 1994-1996, we obtained data on 9,264 visits and conducted 1,772 follow-up interviews. The median interval between symptoms and visit ranged from 0.8 days (95% CI 0-1.7) for cardiac conditions to 4.0 days for chronic obstructive pulmonary disease (COPD) (95% CI 2.7-5.3) and respiratory infections (95% CI 3.5-4.5). Infection was the most common trigger of respiratory visits. Although most had improved at follow-up, symptoms persisted following the visit for a mean of 4.5 days (95% CI 3.8-5.4) for cardiac conditions to 8.4 days (95% CI 7.2-9.5) for COPD. Among adults aged < 70, the mean number of reduced activity days per episode ranged from 4.7 (95% CI 3.9-5.4) for asthma to 6.6 (95% CI 5.9-7.4) for respiratory infections. Our data assist in interpreting epidemiological studies based on administrative data, and illustrate the broad impacts of cardiorespiratory disease episodes.

Assessing diagnostic classification in an emergency department: implications for daily time series studies of air pollution.

Seven independent assessments of diagnosis were obtained for 92 records of nontrauma emergency department visits in Saint John, New Brunswick, Canada, in 1994. The hospital database was 1.18 times as likely (p < 0.05) as six external physician raters to classify visits as cardiorespiratory, which was consistent for high- and low-pollution days. Kappa was 0.70 (95 percent confidence interval (CI) 0.68-0.73). Kappajs were: asthma, 0.69 (95% CI 0.64-0.73); chronic obstructive pulmonary disease, 0.78 (95% CI 0.74-0.83); respiratory infections, 0.53 (95% CI 0.49-0.57); cardiac, 0.84 (95% CI 0.79-0.88); and other, 0.66 (95% CI 0.62-0.71). Substantial or better interobserver agreement was seen, respiratory infections notwithstanding, and there was no evidence of diagnostic bias in relation to daily air pollution level.

Emergency management of migraine: is the headache really over?

OBJECTIVES: To observe headache frequency after release for acute migraine sufferers treated in an ED; to observe the impact after-release headaches and associated symptoms have on quality of life; and to document the variability in migraine management in an emergency setting. METHODS: Prospective observational study, including 24- and 72-hour telephone follow-up. RESULTS: Over a 4-month period, 143 patients with headaches (149 visits) were observed in the ED. Of 108 patients successfully contacted, the incidence of headache in the first 24 hours after release was 49.1%. Forty-two patients left the ED without pain; 13 of these subsequently had return of headache. Sixty-six left with some degree of pain, with 40 having headache persistence at 24 hours. The difference in 24-hour headache rate between the 2 groups is significant (p=0.008). Five patients still had headaches at 72 hours after release, but 54 of 70 contacted had taken medication for their symptoms between 24 and 72 hours after release. Forty-five percent were not back to normal function at 24 hours, while 21 of 70 were still not sleeping well at 72 hours. Finally, 8 different classes of medications were used in the ED for migraine headaches, with 20 patients receiving at least 3 types of medication. CONCLUSIONS: Treatment for acute migraine headache in this emergency setting was variable. Patients not obtaining complete relief in the ED had a higher rate of headache after release than did those who left with no pain. Migraine sufferers may have normal daily function affected for up to 72 hours or longer after ED treatment.

Management of acute asthma in Canada: an assessment of emergency physician behaviour.

The study objective was to assess Canadian emergency physicians for their management preferences and their compliance with recently developed guidelines for treatment of acute asthma in adults. The design was a cross-sectional survey sent to members of the Canadian Association of Emergency Physicians (CAEP) and to the emergency department (ED) directors of all Canadian hospitals with more than 25 beds in November 1992. ED directors who had not responded were sent a second survey in January 1993. The response rates for the survey were 60.1% (362/602) for ED directors and 53.4% (302/586) for CAEP members. Respondents were more likely to be from larger hospitals and to have completed some training beyond general practice level (CCFP, CCFP-EM, ABEM, FRCPC). There were wide variations among respondents in the use of objective measurements of asthma severity (forced expiratory volume in 1 s [FEV1] and peak expiratory flow rates [PEFR]), dosing of bronchodilators, and utilization of systemic corticosteroids. Forty-six percent of respondents used the FEV1 "occasionally" (22.3%) or "never" (23.8%), and 26.7% used PEFR "occasionally" (15.8%) or "never" (10.9%) in asthma management. Ninety-seven percent used nebulized beta agonist "always" (71.3%) or "often" (25.6%), but only 48.5% used the metered dose inhaler (MDI) "always" (11%) or "often" (37.5%). More than a quarter of respondents (27.2%) used doses of beta agonists that were less than those recommended (> every 30-60 min). Oral corticosteroids were prescribed at discharge only "occasionally" (51.1%), "seldom" (18.9%), or "never" (6.5%) in 76.6% of physicians. Physicians with more training were more likely to assess and treat patients according to current asthma treatment guidelines. The survey shows that many Canadian emergency physicians did not follow published recommendations for the care of patients with acute asthma. This finding was especially so with regard to objective evaluation of airflow, aggressive use of beta-agonists, the use of corticosteroids, and in making appropriate arrangements for patient discharge and follow-up.

Association between ozone and asthma emergency department visits in Saint John, New Brunswick, Canada.

This study examines the relationship of asthma emergency department (ED) visits to daily concentrations of ozone and other air pollutants in Saint John, New Brunswick, Canada. Data on ED visits with a presenting complaint of asthma (n = 1987) were abstracted for the period 1984-1992 (May-September). Air pollution variables included ozone, sulfur dioxide, nitrogen dioxide, sulfate, and total suspended particulate (TSP); weather variables included temperature, humidex, dewpoint, and relative humidity. Daily ED visit frequencies were filtered to remove day of the week and long wave trends, and filtered values were regressed on air pollution and weather variables for the same day and the 3 previous days. The mean daily 1-hr maximum ozone concentration during the study period was 41.6 ppb. A positive, statistically significant (p < 0.05) association was observed between ozone and asthma ED visits 2 days later, and the strength of the association was greater in nonlinear models. The frequency of asthma ED visits was 33% higher (95% CI, 10-56%) when the daily 1-hr maximum ozone concentration exceeded 75 ppb (the 95th percentile). The ozone effect was not significantly influenced by the addition of weather or other pollutant variables into the model or by the exclusion of repeat ED visits. However, given the limited number of sampling days for sulfate and TSP, a particulate effect could not be ruled out. We detected a significant association between ozone and asthma ED visits, despite the vast majority of sampling days being below current U.S. and Canadian standards.

Guidelines for the emergency management of asthma in adults. CAEP/CTS Asthma Advisory Committee. Canadian Association of Emergency Physicians and the Canadian Thoracic Society.

OBJECTIVE: To develop a set of comprehensive, standardized evidence-based guidelines for the assessment and treatment of acute asthma in adults in the emergency setting. OPTIONS: The use of medications was evaluated by class, dose, route, onset of action and optimal mode of delivery. The use of objective measurements and clinical features to assess response to therapy were evaluated in relation to the decision to admit or discharge the patient or arrange for follow-up care. OUTCOMES: Control of symptoms and disease reflected in hospital admission rates, frequency of treatment failures following discharge, resolution of symptoms and improvement of spirometric test results. EVIDENCE: Previous guidelines, articles retrieved through a search of MEDLINE, emergency medical abstracts and information from members of the expert panel were reviewed by members of the Canadian Association of Emergency Physicians (CAEP) and the Canadian Thoracic Society. Where evidence was not available, consensus was reached by the expert panel. The resulting guidelines were reviewed by members of the parent organizations. VALUES: The evidence-based methods and values of the Canadian Task Force on the Periodic Health Examination were used. BENEFITS, HARMS AND COSTS: As many as 80% of the approximate 400 deaths from asthma each year in Canada are felt to be preventable. The use of guidelines, aggressive emergency management and consistent use of available options at discharge are expected to decrease the rates of unnecessary hospital admissions and return visits to emergency departments because of treatment failures. Substantial decreases in costs are expected from the use of less expensive drugs, or drug delivery systems, fewer hospital admissions and earlier return to full activity after discharge. RECOMMENDATIONS: Beta2-agonists are the first-line therapy for the management of acute asthma in the emergency department (grade A recommendation). Bronchodilators should be administered by the inhaled route and titrated using objective and clinical measures of airflow limitation (grade A). Metered-dose inhalers are preferred to wet nebulizers, and a chamber (spacer device) is recommended for severe asthma (grade A). Anticholinergic therapy should be added to beta 2 agonist therapy in severe and life-threatening cases and may be considered in cases of mild to moderate asthma (grade A). Aminophylline is not recommended for use in the first 4 hours of therapy (grade A). Ketamine and succinylcholine are recommended for rapid sequence intubation in life-threatening cases (grade B). Adrenaline (administered subcutaneously or intravenously), salbutamol (administered intravenously) and anesthetics (inhaled) are recommended as alternatives to conventional therapy in unresponsive life-threatening cases (grade B). Severity of airflow limitation should be determined according to the forced expiratory volume at 1 second or the peak expiratory flow rate, or both, before and after treatment and at discharge (grade A). Consideration for discharge should be based on both spirometric test results and assessment of clinical risk factors for relapse (grade A). All patients should be considered candidates for systemic corticosteroid therapy at discharge (grade A). Those requiring corticosteroid therapy should be given 30 to 60 mg of prednisone orally (or equivalent) per day for 7 to 14 days; no tapering is required (grade A). Inhaled corticosteroids are an integral component of therapy and should be prescribed for all patients receiving oral corticosteroid therapy at discharge (grade A). Patients should be given a discharge treatment plan and clear instructions for follow-up care (grade C). VALIDATION: The guidelines share the same principles of those from the British Thoracic Society and the National Institutes of Health. Two specific validation initiatives have been undertaken: (a) several Canadian centres have been involved in the collection of comprehensive administrative data to assess compliance and outcome measures and (b) a survey of Canadian emergency physicians conducted to gather baseline informaton of treatment patterns, was conducted before development of the guidelines and will be repeated to re-evaluate emergency management of asthma.