Studying time to pregnancy by use of a retrospective design
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Studying time to pregnancy by use of a retrospective design. / Joffe, Michael; Key, Jane; Best, Nicky; Keiding, Niels; Scheike, Thomas; Jensen, Tina Kold.
In: American Journal of Epidemiology, Vol. 162, No. 2, 2005, p. 115-24.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Studying time to pregnancy by use of a retrospective design
AU - Joffe, Michael
AU - Key, Jane
AU - Best, Nicky
AU - Keiding, Niels
AU - Scheike, Thomas
AU - Jensen, Tina Kold
N1 - Keywords: Bias (Epidemiology); Cohort Studies; Cross-Sectional Studies; Female; Fertility; Fertilization; Humans; Infertility; Male; Maternal Age; Pregnancy; Pregnancy, Unplanned; Research Design; Retrospective Studies; Smoking; Time Factors
PY - 2005
Y1 - 2005
N2 - Biologic fertility can be measured using time to pregnancy (TTP). Retrospective designs, although lacking detailed timed information about behavior and exposure, are useful since they have a well-defined target population, often have good response rates, and are simpler and less expensive to conduct than prospective studies. This paper reviews retrospective TTP studies from a methodological viewpoint and shows how methodological problems can be avoided or minimized by appropriate study design, conduct, and analysis. Sensitivity analyses using data from four European retrospective TTP studies are presented to explore the issues. Although the identified biases tend to have small impacts, the effects are not systematic across studies, and sensitivity analyses are recommended routinely. Planning bias can be checked by comparing propensity to report contraceptive failures in different exposure groups. Medical intervention bias can be avoided by censoring and inclusion of unsuccessful pregnancy attempts. Truncation bias can be a serious problem if unrecognized, but it is avoidable with appropriate study design and/or analysis. Behavior change bias can be minimized by assessing the covariates at the beginning of unprotected intercourse. More complete inference is possible if the study design covers the whole population, not just those who achieve a pregnancy.
AB - Biologic fertility can be measured using time to pregnancy (TTP). Retrospective designs, although lacking detailed timed information about behavior and exposure, are useful since they have a well-defined target population, often have good response rates, and are simpler and less expensive to conduct than prospective studies. This paper reviews retrospective TTP studies from a methodological viewpoint and shows how methodological problems can be avoided or minimized by appropriate study design, conduct, and analysis. Sensitivity analyses using data from four European retrospective TTP studies are presented to explore the issues. Although the identified biases tend to have small impacts, the effects are not systematic across studies, and sensitivity analyses are recommended routinely. Planning bias can be checked by comparing propensity to report contraceptive failures in different exposure groups. Medical intervention bias can be avoided by censoring and inclusion of unsuccessful pregnancy attempts. Truncation bias can be a serious problem if unrecognized, but it is avoidable with appropriate study design and/or analysis. Behavior change bias can be minimized by assessing the covariates at the beginning of unprotected intercourse. More complete inference is possible if the study design covers the whole population, not just those who achieve a pregnancy.
U2 - 10.1093/aje/kwi172
DO - 10.1093/aje/kwi172
M3 - Journal article
C2 - 15972942
VL - 162
SP - 115
EP - 124
JO - American Journal of Epidemiology
JF - American Journal of Epidemiology
SN - 0002-9262
IS - 2
ER -
ID: 14359772