Experience with multiple control groups in a large population-based case–control study on genetic and environmental risk factors


Pomp, E.R. and Stralen, K.J. van and Cessie, S. le and Vandenbroucke, J.P. and Rosendaal, F.R. and Doggen, C.J.M. (2010) Experience with multiple control groups in a large population-based case–control study on genetic and environmental risk factors. European journal of epidemiology, 25 . pp. 459-466. ISSN 03932990

Abstract:We discuss the analytic and practical considerations
in a large case–control study that had two control
groups; the first control group consisting of partners of
patients and the second obtained by random digit dialling
(RDD). As an example of the evaluation of a general lifestyle
factor, we present body mass index (BMI). Both control
groups had lower BMIs than the patients. The
distribution in the partner controls was closer to that of the
patients, likely due to similar lifestyles. A statistical
approach was used to pool the results of both analyses,
wherein partners were analyzed with a matched analysis,
while RDDs were analyzed without matching. Even with a
matched analysis, the odds ratio with partner controls
remained closer to unity than with RDD controls, which is
probably due to unmeasured confounders in the comparison
with the random controls as well as intermediary factors.
However, when studying injuries as a risk factor, the odds
ratio remained higher with partner control subjects than with
RRD control subjects, even after taking the matching into
account. Finally we used factor V Leiden as an example of a
genetic risk factor. The frequencies of factor V Leiden were
identical in both control groups, indicating that for the
analyses of this genetic risk factor the two control groups
could be combined in a single unmatched analysis. In conclusion,
the effect measures with the two control groups
were in the same direction, and of the same order of magnitude.
Moreover, it was not always the same control group
that produced the higher or lower estimates, and a matched
analysis did not remedy the differences. Our experience
with the intricacies of dealing with two control groups may
be useful to others when thinking about an optimal research
design or the best statistical approach.
Item Type:Article
Additional information:Open access journal
Copyright:© The authors
Management and Governance (SMG)
Research Group:
Link to this item:http://purl.utwente.nl/publications/76793
Official URL:http://dx.doi.org/10.1007/s10654-010-9475-z
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