{"id":300,"date":"2013-02-12T17:46:29","date_gmt":"2013-02-12T16:46:29","guid":{"rendered":"http:\/\/stg-blogs.bmj.com\/adc-archimedes\/?p=300"},"modified":"2013-03-15T17:15:06","modified_gmt":"2013-03-15T16:15:06","slug":"chorio-and-nec","status":"publish","type":"post","link":"https:\/\/stg-blogs.bmj.com\/adc\/2013\/02\/12\/chorio-and-nec\/","title":{"rendered":"Chorioamnionitis and NEC – the challenge of significant small associations"},"content":{"rendered":"

\"CoverIn a recent flurry of twittering, Archimedes noticed a meta-analysis linking chorioamnionitis with necrotising enterocolitis<\/a>. Although a long time since doing neonates has passed, the consequences of NEC were profound enough to stick, and a potential association, perhaps a route in to stopping it happen, would be welcome.<\/p>\n

The meta-analysis showed that, on univariate examination, there was a positive relationship between clinical chorioamninonitis and significant NEC (Bell stage 2 or worse), with an OR of approximately 1.3.<\/p>\n

To convert this to something more clinically useful – say, the proportion of chorioamnionitis-born-babies who’d develop NEC, and the proportion who didn’t have a mum with CC but got NEC anyway – needed to know approximate average rates of NEC and CC.<\/p>\n

A large multicentre US study by Yee<\/a> helps us out here, with around 5% of preterm infants getting NEC and about 11% on non-NEC babies having mums with CC.\u00a0Popping these values into a theoretical cohort of 1000 neonates leads to:<\/p>\n\n\n<\/colgroup>\n\n\n\n\n\n
<\/td>\nNEC<\/td>\nNot<\/td>\n<\/tr>\n
CC<\/td>\n7<\/td>\n105<\/td>\n<\/tr>\n
Not<\/td>\n43<\/td>\n845<\/td>\n<\/tr>\n
<\/td>\n50<\/td>\n950<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The positive predictive value of CC for NEC is about 6.2%, and the rate of ‘unsuspected’ NEC in the non-CC group would be 4.8%<\/p>\n

This highlights the trouble with relative measures of association in relatively rare conditions; you don’t actually end up knowing a lot more than when you started.<\/p>\n

Archi<\/p>\n

(Many thanks for the leads into this from @PaedsRH<\/a> and @Jfphol<\/a>)<\/p>\n","protected":false},"excerpt":{"rendered":"

In a recent flurry of twittering, Archimedes noticed a meta-analysis linking chorioamnionitis with necrotising enterocolitis. Although a long time since doing neonates has passed, the consequences of NEC were profound enough to stick, and a potential association, perhaps a route in to stopping it happen, would be welcome. The meta-analysis showed that, on univariate examination, […]<\/p>\n

Read More…<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[79],"tags":[],"class_list":["post-300","post","type-post","status-publish","format-standard","hentry","category-archimedes"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts\/300","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/comments?post=300"}],"version-history":[{"count":0,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/posts\/300\/revisions"}],"wp:attachment":[{"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/media?parent=300"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/categories?post=300"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stg-blogs.bmj.com\/adc\/wp-json\/wp\/v2\/tags?post=300"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}