Interaction and its solution in individual matching case-control study.
OBJECTIVE
To indicate the deficiency of the classical method for analyzing data on individual matching case-control study in consideration of the interaction between the study factor (exposure) and the matching factor, and to find out a proper method for handling this deficiency.


METHODS
First, experimental data with 50 pairs of cases and controls were used for strata analysis according to the values of a matching factor to illustrate the possible interaction between a risk factor (exposure) and the matching factor. Second, a detailed procedure was proposed for analyzing such data.


RESULTS
Interaction between the study factor and matching factor was demonstrated by using strata analysis and unconditional logistic regression analysis. Therefore the results from the classical analysis for such data might be incorrect.


CONCLUSIONS
Data from individual matching case-control study design should be dealt with strata analysis or multivariate analysis to explore and evaluate the possible interaction between the study factor and matching factor. The conclusion would be valid only after such analysis is conducted.
Center for Public Health Surveillance and Information Services, Chinese Center for Disease Prevention and Control, 27 Nan Wei Road, Beijing 100050, China.
Xiao-Xin
XX
He
Shui-Gao
SG
Jin
D016022:Case-Control Studies; D015986:Confounding Factors, Epidemiologic; D016555:Matched-Pair Analysis; D017063:Outcome Assessment, Health Care; D012044:Regression Analysis; D012307:Risk Factors