Open AccessImmortal Time Bias in the Study of Stillbirth Risk Factors
Author(s) -
Jennifer A. Hutcheon,
Verena Kuret,
K. S. Joseph,
Yasser Sabr,
Kenneth Lim
Publication year - 2013
Publication title -
epidemiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.901
H-Index - 173
eISSN - 1531-5487
pISSN - 1044-3983
DOI - 10.1097/ede.0b013e3182a6d9aa
Subject(s) - gestational diabetes , medicine , obstetrics , gestation , confidence interval , relative risk , pregnancy , diabetes mellitus , cohort study , cohort , endocrinology , biology , genetics
Current understanding of the increased risk for stillbirth in gestational diabetes mellitus is often based on large cohort studies in which the risk of stillbirth in women with this disease is compared with the risk in women without. However, such studies could be susceptible to immortal time bias because, although many cohorts begin at 20 weeks' gestation, pregnancies must "survive" until 24-28 weeks in order to be screened and diagnosed with gestational diabetes.