Neil W. Johnston

The September epidemic of asthma exacerbations in children: A search for etiology

Background Predictable peaks of asthma exacerbation requiring hospital treatment, of greatest magnitude in children and of uncertain etiology, occur globally after school returns. Objective We wished to determine whether asthmatic children requiring emergency department treatment for exacerbations after school return in September were more likely to have respiratory viruses present and less likely to have prescriptions for control medications than children with equally severe asthma not requiring emergent treatment. Methods Rates of viral detection and characteristics of asthma management in 57 (of 60) children age 5 to 15 years presenting to emergency departments with asthma in 2 communities in Canada between September 10 and 30, 2001, (cases) were compared with those in 157 age-matched volunteer children with asthma of comparable severity studied simultaneously (controls). Results Human picornaviruses were detected in 52% of cases and 29% of controls (P =.002) and viruses of any type in 62% of cases and 41% of controls (P =.011). Cases were less likely to have been prescribed controller medication (inhaled corticosteroid, 49% vs 85%; P < .0001; leukotriene receptor antagonist, 9% vs 21%; P =.04). Conclusion Respiratory viruses were detected in the majority of children presenting to emergency departments with asthma during the September epidemic of the disease and in a significant minority of children with asthma in the community. The latter were more likely to have anti-inflammatory medication prescriptions than children requiring emergent treatment. Such medication may reduce the risk of emergency department treatment for asthma during the September epidemic.

Attenuation of the September Epidemic of Asthma Exacerbations in Children: A Randomized, Controlled Trial of Montelukast Added to Usual Therapy

BACKGROUND. A recurring epidemic of asthma exacerbations in children occurs annually in September in North America when school resumes after summer vacation. OBJECTIVE. Our goal was to determine whether montelukast, added to usual asthma therapy, would reduce days with worse asthma symptoms and unscheduled physician visits of children during the September epidemic. PATIENTS AND METHODS. A total of 194 asthmatic children aged 2 to 14 years, stratified according to age group (2–5, 6–9, and 10–14 years) and gender, participated in a double-blind, randomized, placebo-controlled trial of the addition of montelukast to usual asthma therapy between September 1 and October 15, 2005. RESULTS. Children randomly assigned to receive montelukast experienced a 53% reduction in days with worse asthma symptoms compared with placebo (3.9% vs 8.3%) and a 78% reduction in unscheduled physician visits for asthma (4 [montelukast] vs 18 [placebo] visits). The benefit of montelukast was seen both in those using and not using regular inhaled corticosteroids and among those reporting and not reporting colds during the trial. There were differences in efficacy according to age and gender. Boys aged 2 to 5 years showed greater benefit from montelukast (0.4% vs 8.8% days with worse asthma symptoms) than did older boys, whereas among girls the treatment effect was most evident in 10- to 14-year-olds (4.6% [montelukast] vs 17.0% [placebo]), with nonsignificant effects in younger girls. CONCLUSIONS. Montelukast added to usual treatment reduced the risk of worsened asthma symptoms and unscheduled physician visits during the predictable annual September asthma epidemic. Treatment-effect differences observed between age and gender groups require additional investigation.

Understanding the september asthma epidemic

The highly predictable increase in emergency department visits, hospital admissions, and unscheduled physician consultations for childhood asthma in North America every September is uniquely related to school return. Rhinovirus infection is likely the major trigger, initially affecting asthma in school-age children, followed by similar but lesser increases in asthma morbidity in younger children and in adults. Low use of asthma medications during summer may fuel the epidemic, which may be attenuated by the short-term addition of an effective controller therapy.

Detection of COPD Exacerbations and Compliance With Patient-Reported Daily Symptom Diaries Using a Smartphone-Based Information System

Background Paper-based diaries and self-report of symptom worsening in COPD may lead to underdetection of exacerbations. Epidemiologically, COPD exacerbations exhibit seasonal patterns peaking at year-end. We examined whether the use of a BlackBerry-based daily symptom diary would detect 95% or more of exacerbations and enable characterization of seasonal differences among them. Methods Fifty participants with GOLD (Global Initiative for Chronic Obstructive Lung Disease) stage I to IV COPD began a community-based study in December 2007. Another 30 began in December 2008. Participants transmitted daily symptom diaries using a BlackBerry. Alerts were triggered when symptom changes, missed diary transmissions, or medical care for a respiratory problem occurred. Participant encounters were initiated if COPD exacerbations were suspected. Participants used their BlackBerrys to report returns to normal breathing. Results Participants transmitted 99.9% of 28,514 possible daily diaries. All 191 (2.5/participant-year) COPD exacerbations meeting Anthonisen criteria were detected. During 148 of the 191 exacerbations (78%, 1.97/participant-year), patients were hospitalized and/or ordered prednisone, an antibiotic, or both. Respiratory viruses were detected in 78 of the 191 exacerbations (41%). Those coinciding with a respiratory viral infection averaged 12.0 days, and those without averaged 8.9 days (P < .04), with no difference in Anthonisen score. Respiratory symptom scores before exacerbations and after normal breathing return showed no differences. Exacerbations were more frequent during the Christmas period than the rest of the year but were not more frequent than in the rest of winter alone. Conclusions Smartphone-based collection of COPD symptom diaries enables near-complete identification of exacerbations at inception. Exacerbation rates in the Christmas season do not reach levels that necessitate changes in disease management.

Biomedical surveillance: rights conflict with rights.

Medical screening and biomedical monitoring violate individual rights. Such conflicts of right with right are acted upon synergistically by uncertainty which, in some important respects, increases rather than decreases as a result of research. Issues of rightness and wrongness, ethical issues, arise because the human beings who are subjects of medical screening and biological monitoring often have little or no option whether to be subjected to them. We identify issues of rightness and wrongness of biomedical surveillance for various purposes of occupational health and safety. We distinguish between social validity and scientific validity. We observe that principles are well established for scientific validity, but not for social validity. We support guidelines as a way forward.

Seasonal and geographic variations in the incidence of asthma exacerbations in the United States

ABSTRACT Background: Exacerbations drive the burden of asthma and lead to significant morbidity and consumption of health care resources. Many prior studies of the epidemiology of asthma exacerbations have relied upon data from hospital care. Objective: The objective of this study was to determine US patterns of geographic and seasonal variations of asthma exacerbations being defined as asthma episodes requiring hospital care and/or a prescription for oral steroid. Methods: The study was a retrospective observational cohort study using administrative claims data for insured individuals from the HealthCore Integrated Research Database, including around 43 million members in the United States. Analyses examined 3 age groups, 6–17, 18–64, and ≥65 years and four US regions, Northeast, Southeast, Central, and Western. Results: Monthly rates of asthma exacerbations showed the greatest variation over the year in children, less so in adults and in the elderly. Clinically important differences in rates of asthma exacerbation were observed between regions with the Western Region having the lowest in all three age groups followed by the Northeast, Central, and Southeast regions. Peaks in children occurred in the early fall following troughs in the summer months, and peaks at year-end occurred in adults, particularly in those over 65 years. Conclusions: There is a striking seasonal variation in asthma exacerbations in the United States. Substantial differences between regions of the United States in asthma exacerbation rates cannot readily be explained and invite further investigation.

Colds as predictors of the onset and severity of COPD exacerbations

Rationale Common colds are associated with acute respiratory symptom exacerbations in COPD patients. Objective To determine exacerbation risk and severity in COPD patients with/without coincident self-reported colds. Methods Global initiative for chronic Obstructive Lung Disease stage I–IV COPD patients electronically transmitted respiratory symptom diaries to research staff daily between December 2006 and April 2009. Respiratory symptom worsening prompted contact by a study nurse and patient assessment to determine if a cold was present or an exacerbation underway. A composite daily symptom score was derived for each subject from diarized symptom data. The exacerbation/cold/virus relation was examined using a Poisson regression model, the relation of colds to respiratory symptom severity using generalized estimating equation models. Results Daily diary transmission compliance of >97% enabled detection of all possible exacerbations. Among 262 exacerbations meeting Anthonisen criteria, 218 (83%) had cold-like symptoms present at their inception, but respiratory viruses were detected in only 106 (40%). Within-subject exacerbation risk was 30 times (95% confidence interval [CI]: 20, 47; P<0.001) greater with colds present. Compared to cold- and virus-negative exacerbations (n=57), the mean increase in composite symptom score in those cold and virus positive (n=79) was 0.93 (95% CI: 0.61, 1.25; P<0.001), cold-positive and virus-negative exacerbations (n=100) 0.51 (95% CI: 0.21, 0.81; P<0.001), cold-negative and virus-positive exacerbations (n=26) 0.58 (95% CI: 0.23, 0.94; P<0.001). Conclusion This study emphasizes the importance of colds in COPD exacerbation risk and severity, even in the absence of virus detection. COPD patients should act promptly when cold symptoms appear to facilitate early intervention for exacerbation prevention or management.

Gender Differences in the Effectiveness of Asthma Treatment: In Reply

We did not explicitly acknowledge the possible role of dysanapsis in our findings in the report of our study of the effectiveness of montelukast in children during the September epidemic of asthma.1 We appreciate the letter by de Benedictis et al, which offers an …