Spouse controls in family case-control studies: a methodological consideration

In case-control studies on familial aggregation of disease, spouses may be chosen as convenient controls. In this article the pros and cons of this control group are discussed. It is argued that the use of spouse controls can be time- and cost-efficient, because of easy accessibility and their ability to provide proxy data on the patients' relatives if necessary. Furthermore, with spouse controls a higher response rate and less recall bias can be expected compared to population controls. A theoretical drawback is the possibility of assortative mating related to genetic susceptibility of the disease under study. Using a simulation study it is illustrated that even strong assortative mating on a factor, which is strongly correlated with a true risk factor under study, will have a negligible effect on the observed extent of familial aggregation.