Seasonal changes in the incidence of Escherichia coli bloodstream infection: variation with region and place of onset.

Previous research has shown that Escherichia coli infection rates peak in the summer; however, to date there has been no investigation as to whether this is seen in both hospital and community-onset cases, and how this differs across regions. We investigated and quantified E. coli bloodstream infection (BSI) seasonality. A generalized additive Poisson model was fitted to mandatory E. coli BSI surveillance data reported in England. There was no impact of seasonality in hospital-onset cases; however, for the community-onset cases, there was statistically significant seasonal variation over time nationally. When examined regionally, seasonality was significant in the North of England only. This variation resulted in an absolute increase of 0.06 (95% CI 0.02-0.1) cases above the mean (3.25) in each hospital trust for each week of the peak summer season, and a decrease of (-) 0.07 (95% CI -0.1 to -0.03) in the autumn. We estimate that fewer than one hospital bed-day per week per hospital is lost because of seasonal increases during the summer. Our findings highlight the need to understand the distinct community and hospital dynamics of E. coli BSI, and to explore the regional differences driving the variation in incidence, in order to design and implement effective control measures.

Impact of Caesarean section on subsequent fertility: a systematic review and meta-analysis.

STUDY QUESTION: Is there an association between a Caesarean section and subsequent fertility? SUMMARY ANSWER: Most studies report that fertility is reduced after Caesarean section compared with vaginal delivery. However, studies with a more robust design show smaller effects and it is uncertain whether the association is causal. WHAT IS KNOWN ALREADY: A previous systematic review published in 1996 summarizing six studies including 85 728 women suggested that Caesarean section reduces subsequent fertility. The included studies suffer from severe methodological limitations. STUDY DESIGN, SIZE, DURATION: Systematic review and meta-analysis of cohort studies comparing subsequent reproductive outcomes of women who had a Caesarean section with those who delivered vaginally. PARTICIPANTS/MATERIALS, SETTING, METHODS: Searches of Cochrane Library, Medline, Embase, CINAHL Plus and Maternity and Infant Care databases were conducted in December 2011 to identify randomized and non-randomized studies that compared the subsequent fertility outcomes after a Caesarean section and after a vaginal delivery. Eighteen cohort studies including 591 850 women matched the inclusion criteria. Risk of bias was assessed by the Newcastle-Ottawa scale (NOS). Data extraction was done independently by two reviewers. The meta-analysis was based on a random-effects model. Subgroup analyses were performed to assess whether the estimated effect was influenced by parity, risk adjustment, maternal choice, cohort period, and study quality and size. MAIN RESULTS AND THE ROLE OF CHANCE: The impact of Caesarean section on subsequent pregnancies could be analysed in 10 studies and on subsequent births in 16 studies. A meta-analysis suggests that patients who had undergone a Caesarean section had a 9% lower subsequent pregnancy rate [risk ratio (RR) 0.91, 95% confidence interval (CI) (0.87, 0.95)] and 11% lower birth rate [RR 0.89, 95% CI (0.87, 0.92)], compared with patients who had delivered vaginally. Studies that controlled for maternal age or specifically analysed primary elective Caesarean section for breech delivery, and those that were least prone to bias according to the NOS reported smaller effects. LIMITATIONS, REASONS FOR CAUTION: There is significant variation in the design and methods of included studies. Residual bias in the adjusted results is likely as no study was able to control for a number of important maternal characteristics, such as a history of infertility or maternal obesity. WIDER IMPLICATIONS OF THE FINDINGS: Further research is needed to reduce the impact of selection bias by indication through creating more comparable patient groups and applying risk adjustment.