RT Journal
A1 Kirby RS, Marshall J
T1 HOspital-based clusters and the epidemiology of gastroschisis
JF Archives of Pediatrics & Adolescent Medicine
JO Archives of Pediatrics & Adolescent Medicine
YR 2010
FD June 1
VO 164
IS 6
SP 583
OP 584
DO 10.1001/archpediatrics.2010.79
UL http://dx.doi.org/10.1001/archpediatrics.2010.79
AB 
While the authors refer to the case series as a cluster in the title and throughout the article, they provide no statistical results of analyses to determine whether the case series meets formal criteria for a statistical cluster, nor does their methodology follow established guidelines for cluster investigations.2- 3 The authors also fail to indicate whether prenatally diagnosed and electively terminated cases were included in the case series. Additionally, the authors do not indicate whether the series consisted exclusively of cases of isolated gastroschisis, yet multiple defects indicate a more complex etiology.4 For example, were cases of limb-body wall defect excluded? Third, epidemiologists typically define clusters by place of residence; of special interest here would be residence prior to conception or during the first trimester of the index pregnancy. While the reported birth prevalence estimate of 22.6 of 10 000 live births (95% confidence interval, 12.8-37.0) is higher than many recently published state-level estimates, this estimate potentially falls within normal limits if the catchment area for the denominator is broader than that used for this calculation.5