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Time to Tweak our Lead-Screening Questionnaire? :
In the hierarchy of evidence, aka the "evidence pyramid," retrospective case series don't rank very highly.

January 17, 2017

In the hierarchy of evidence, aka the "evidence pyramid," retrospective case series don't rank very highly. However, this one is worth consideration for changing your practice in screening children for lead poisoning risk.

One child suffered lead poisoning from a batch of dried, spiced grasshoppers  (chapulinas) from Mexico. From Wikimedia via Olajide.TV .
One child suffered lead poisoning from a batch of dried, spiced grasshoppers (chapulinas) from Mexico. From Wikimedia via Olajide.TV .
In the hierarchy of evidence, aka the "evidence pyramid," retrospective case series don't rank very highly. However, this one is worth consideration for changing your practice in screening children for lead poisoning risk.

Source: Keller B, Faciano A, Tsega A, et al. Epidemiologic characteristics of children with blood lead levels ≥45μg/dL. J Pediatr 2017; 180:229-234. doi:10.1016/j.jpeds.2016.09.017. See AAP Grand Rounds commentary by Dr. Jeffrey Winer (subscription required).

This study describes 145 New York City children discovered to have blood lead levels (BLLs) above 45 mcg/dL during the period 2004-2010. The methods for detecting such cases changed over the study period, and the authors do a nice job explaining how this might have confounded their results. I guess one could take a glass half-full approach that there were relatively few seriously increased BLLs in such a large population, but my initial response was definitely the reverse; we really shouldn't be seeing any children in this country with dangerously elevated BLLs.

The risk factors found in this study aren't necessarily new, but are worth noting. Major risks included eating paint, spending time outside the US, being diagnosed with developmental delay, using imported products (foods, pottery, cosmetics like surma from Pakistan, and medicines), being foreign-born (Pakistani in particular in this cohort), eating soil, and having sickle cell disease. It's worth reading the article for the discussions on these risks. Black or Asian background and living in housing built before 1940 were also associated factors.

A couple other items of note caught my attention as well. First, 4 of the 145 children were newborns, reminding us that lead exposure in mothers is an important risk factor. Second, once these children were diagnosed with high BLLs, it takes a while for treatment to bring down the BLLs, with their patients requiring between 0 and 9 rounds of chelation therapy.

The AAP recommendations for lead screening, via its Bright Futures publication, references a CDC publication; check it out for the nice table on risk factors for lead exposure in pregnant and lactating women. However, lead exposure risks vary by community, and thus local and state guidelines for screening can vary as well. Please be sure you are up to date with your local guidance.

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