Applicability of the Brighton Collaboration Case Definition for seizure after immunization in active and passive surveillance in Canada.

BACKGROUND: The Canadian Adverse Event Following Immunization Surveillance System (CAEFISS) receives reports via active syndromic surveillance for selected serious AEFI from the Canadian Immunization Monitoring Program Active (IMPACT) and via targeted passive surveillance from Federal/Provincial/Territorial health jurisdictions. Post-immunization seizure is a target of active and passive surveillance. Since 2009, the revised national AEFI reporting forms enable capture of terms specific to several Brighton Collaboration Case Definitions (BCCD) including generalized seizure and fever. OBJECTIVE: To evaluate feasibility of applying the BCCD for generalized seizure to adverse event following immunization (AEFI) reports collected by IMPACT and targeted passive surveillance (non-IMPACT). METHODS: Reports to CAEFISS coded as seizure in children <2 years of age (vaccination dates 1998-2011) were reviewed retrospectively. A BCCD level (1-5 or unclassifiable) was assigned. The effects of reporting source (IMPACT versus non-IMPACT), seriousness [serious (e.g., hospitalized) versus non-serious], vaccination year (1998-2008 versus 2009-2011), and data submission method to CAEFISS (electronic versus paper) were assessed by stratified analysis. RESULTS: There were 459 IMPACT and 908 non-IMPACT cases analyzed, of which 99.6% and 27%, respectively, were serious reports. The revised reporting form that captured the BCCD components (2009-2011) was associated with increased proportions of IMPACT and non-IMPACT cases meeting the BCCD for generalized seizure. CONCLUSIONS: Incorporating the BCCD components (level of consciousness, motor manifestations and fever ≥38°C) into the national reporting form and guidelines appeared to improve the feasibility of their use in AEFI surveillance. This effect was more pronounced among active syndromic surveillance compared to targeted passive surveillance reports.

The risk of adverse pregnancy outcomes is increased in preeclamptic women who smoke compared with nonpreeclamptic women who do not smoke.

OBJECTIVE: Maternal smoking and preeclampsia independently increase the risk of adverse pregnancy outcomes; however, smoking decreases the risk of preeclampsia. We sought to estimate the risk of adverse pregnancy outcomes among preeclamptic women who smoke and hypothesized that this risk would be increased, compared with nonpreeclamptic women who smoke or preeclamptic women who do not smoke. STUDY DESIGN: With the use of the Niday Perinatal Database and multiple logistic regressions, we estimated the risk of adverse pregnancy outcomes in nonpreeclamptic women who smoke, preeclamptic women who do not smoke, and preeclamptic women who smoke in relation to nonpreeclamptic women who do not smoke. RESULTS: The incidence of adverse pregnancy outcomes was more than twice as high among preeclamptic women who smoke as among nonpreeclamptic women who do not smoke. The following data were observed: small-for-gestational-age infant (odds ratio [OR], 3.40; 95% CI, 2.27-4.89), preterm birth (OR, 5.77; 95% CI, 4.50-7.35), very preterm birth (OR, 5.44; 95% CI, 3.51-8.11), abruption (OR, 6.16; 95% CI, 3.05-11.01), Apgar <4 at 5 minutes (OR, 3.11; 95% CI, 1.48-5.72), and stillbirth (OR, 3.39; 95% CI, 1.33-6.99). CONCLUSION: Smoking decreases the risk of preeclampsia, but smokers with preeclampsia have an increased risk for adverse pregnancy outcomes.

Quantifying the impact of community quarantine on SARS transmission in Ontario: estimation of secondary case count difference and number needed to quarantine.

BACKGROUND: Community quarantine is controversial, and the decision to use and prepare for it should be informed by specific quantitative evidence of benefit. Case-study reports on 2002-2004 SARS outbreaks have discussed the role of quarantine in the community in transmission. However, this literature has not yielded quantitative estimates of the reduction in secondary cases attributable to quarantine as would be seen in other areas of health policy and cost-effectiveness analysis. METHODS: Using data from the 2003 Ontario, Canada, SARS outbreak, two novel expressions for the impact of quarantine are presented. Secondary Case Count Difference (SCCD) reflects reduction in the average number of transmissions arising from a SARS case in quarantine, relative to not in quarantine, at onset of symptoms. SCCD was estimated using Poisson and negative binomial regression models (with identity link function) comparing the number of secondary cases to each index case for quarantine relative to non-quarantined index cases. The inverse of this statistic is proposed as the number needed to quarantine (NNQ) to prevent one additional secondary transmission. RESULTS: Our estimated SCCD was 0.133 fewer secondary cases per quarantined versus non-quarantined index case; and a NNQ of 7.5 exposed individuals to be placed in community quarantine to prevent one additional case of transmission in the community. This analysis suggests quarantine can be an effective preventive measure, although these estimates lack statistical precision. CONCLUSIONS: Relative to other health policy areas, literature on quarantine tends to lack in quantitative expressions of effectiveness, or agreement on how best to report differences in outcomes attributable to control measure. We hope to further this discussion through presentation of means to calculate and express the impact of population control measures. The study of quarantine effectiveness presents several methodological and statistical challenges. Further research and discussion are needed to understand the costs and benefits of enacting quarantine, and this includes a discussion of how quantitative benefit should be communicated to decision-makers and the public, and evaluated.