A retrospective cohort study of stroke onset: implications for characterizing short term effects from ambient air pollution

<p>Abstract</p> <p>Background</p> <p>Case-crossover studies used to investigate associations between an environmental exposure and an acute health response, such as stroke, will often use the day an individual presents to an emergency department (ED) or is admitted to hospital to infer when the stroke occurred. Similarly, they will use patient's place of residence to assign exposure. The validity of using these two data elements, typically extracted from administrative databases or patient charts, to define the time of stroke onset and to assign exposure are critical in this field of research as air pollutant concentrations are temporally and spatially variable. Our a priori hypotheses were that date of presentation differs from the date of stroke onset for a substantial number of patients, and that assigning exposure to ambient pollution using place of residence introduces an important source of exposure measurement error. The objective of this study was to improve our understanding on how these sources of errors influence risk estimates derived using a case-crossover study design.</p> <p>Methods</p> <p>We sought to collect survey data from stroke patients presenting to hospital EDs in Edmonton, Canada on the date, time, location and nature of activities at onset of stroke symptoms. The daily mean ambient concentrations of NO₂and PM_2.5on the self-reported day of stroke onset was estimated from continuous fixed-site monitoring stations.</p> <p>Results</p> <p>Of the 336 participating patients, 241 were able to recall when their stroke started and 72.6% (95% confidence interval [CI]: 66.9 - 78.3%) experienced stroke onset the same day they presented to the ED. For subjects whose day of stroke onset differed from the day of presentation to the ED, this difference ranged from 1 to 12 days (mean = 1.8; median = 1). In these subjects, there were no systematic differences in assigned pollution levels for either NO₂or PM_2.5when day of presentation rather than day of stroke onset was used. At the time of stroke onset, 89.9% (95% CI: 86.6 - 93.1%) reported that they were inside, while 84.5% (95% CI: 80.6 - 88.4%) reported that for most of the day they were within a 15 minute drive from home. We estimated that due to the mis-specification of the day of stroke onset, the risk of hospitalization for stroke would be understated by 15% and 20%, for NO₂and PM_2.5, respectively.</p> <p>Conclusions</p> <p>Our data suggest that day of presentation and residential location data obtained from administrative records reasonably captures the time and location of stroke onset for most patients. Under these conditions, any associated errors are unlikely to be an important source of bias when estimating air pollution risks in this population.</p

Gastroenteritis Therapies in Developed Countries: Systematic Review and Meta-Analysis

<div><p>Context</p><p>Gastroenteritis remains a leading cause of childhood morbidity.</p><p>Objective</p><p>Because prior reviews have focused on isolated symptoms and studies conducted in developing countries, this study focused on interventions commonly considered for use in developed countries. Intervention specific, patient-centered outcomes were selected.</p><p>Data Sources</p><p>MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews, trial registries, grey literature, and scientific meetings.</p><p>Study Selection</p><p>Randomized controlled trials, conducted in developed countries, of children aged <18 years, with gastroenteritis, performed in emergency department or outpatient settings which evaluated oral rehydration therapy (ORT), antiemetics, probiotics or intravenous fluid administration rate.</p><p>Data Extraction</p><p>The study was conducted in accordance with the Cochrane Handbook for Systematic Reviews of Interventions and the PRISMA guidelines. Data were independently extracted by multiple investigators. Analyses employed random effects models.</p><p>Results</p><p>31 trials (4,444 patients) were included. <i>ORT</i>: Compared with intravenous rehydration, hospitalization (RR 0.80, 95%CI 0.24, 2.71) and emergency department return visits (RR 0.86, 95%CI 0.39, 1.89) were similar. <i>Antiemetics</i>: Fewer children administered an antiemetic required intravenous rehydration (RR 0.40, 95%CI 0.26, 0.60) While the data could not be meta-analyzed, three studies reported that ondansetron administration does increase the frequency of diarrhea. <i>Probiotics</i>: No studies reported on the primary outcome, three studies evaluated hospitalization within 7 days (RR 0.87, 95%CI 0.25, 2.98). <i>Rehydration</i>: No difference in length of stay was identified for rapid vs. standard intravenous or nasogastric rehydration. A single study found that 5% dextrose in normal saline reduced hospitalizations compared with normal saline alone (RR 0.70, 95% CI 0.53, 0.92).</p><p>Conclusions</p><p>There is a paucity of patient-centered outcome evidence to support many interventions. Since ORT is a low-cost, non-invasive intervention, it should continue to be used. Routine probiotic use cannot be endorsed at this time in outpatient children with gastroenteritis. Despite some evidence that ondansetron administration increases diarrhea frequency, emergency department use leads to reductions in intravenous rehydration and hospitalization. No benefits were associated with ondansetron use following emergency department discharge.</p></div

Correction: Gastroenteritis Therapies in Developed Countries: Systematic Review and Meta-Analysis.

[This corrects the article DOI: 10.1371/journal.pone.0128754.]

Adverse Events.

<p>IVT, Intravenous Therapy; ORT, Oral Rehydration Therapy; GI, Gastrointestinal; IV, Intravenous; NA, Not Applicable.</p><p>* Risk ratio calculated where there was at least one incidence in each group</p><p>† Statistically significant difference between groups</p><p>‡ Based on risk difference</p><p>Adverse Events.</p

Meta-graph comparing any antiemetic therapy vs. placebo.

<p>Results from meta-analysis of direct comparisons of therapy with any antiemetic agent vs. placebo on the outcomes of administration of intravenous hydration, admission to hospital from the emergency department and revisits to the emergency departments, displayed employing Forest plots.</p

Flow diagram of study selection.

<p>SR, systematic review; PICO, Population, Intervention, Comparison, Outcome; RCT, randomized controlled trial.</p

Overview of studies included in systematic review.

<p>Overview of studies included in systematic review.</p

Summary of differing recommendations of prominent gastroenteritis guidelines.

<p>Summary of differing recommendations of prominent gastroenteritis guidelines.</p