Estimating the Quantitative Relationship of Disease Control and Spouse Control for Lung Cancer in Case-control Study by Cross-walk Model

Background Disease control (DC) and spouse control (SC) are commonly used in case-control study. The exposure risk of these two kinds of control may be different, especially in tobacco exposure status which attribute to diseases. However, few study concentrates on the association of DC and SC. Based on this situation, this study aims to explore the quantitative relationship of DC and SC for lung cancer. Methods In this study, the data of cases, DC and SC were collected from the National Retrospective Survey of Deaths, including one million deaths during 1986 to 1988. Referring to cross-walk model, four forms of model, stratified by urban/rural areas and genders, were established to explore the suitable one, for adjusting the Odds Ratio (OR) of DC OR _dc and SC OR _sc ). Results A total of 51217 cases, 29871 SCs, and 215018 DCs were collected, among which the male accounted for 68.00%, 24.60% and 54.86%, respectively. Accordingly, the smoking prevalence were 66.83%, 24.39%, 40.21%. The case had the highest smoking rate, following by DC and SC in both genders of urban and rural area. In both urban and rural areas, the OR _sc of males and females were higher than OR _dc . The OR _sc and OR _dc value gradually increases with the age group, reaching its maximum at 60–64 in urban area and 55–59 in rural area. After establishing the cross-walk model, in urban area, logit ( OR _sc )=1.33 logit ( OR _dc ) and logit ( OR _sc )=-0.34+1.35 logit ( OR _dc ) were used for males and females, respectively. In rural area, logit ( OR _sc ) =1.09 logit ( OR _dc ) and logit ( OR _sc ) =1.15 logit ( OR _dc ) were used for males and females, respectively. Conclusions OR _sc are commonly larger than OR _dc in the same urban/rural, gender and age group. Thus, when different types of control are used in the design or analysis of case-control study, the distinction of controls should be considered, especially the quantitative relationship. This study provided an adjustable method for two definitions, which will provide methodological reference for further research.