Appendix Table 2. Confounders Controlled for in the Studies' Adjusted Relative Risk Estimates for the Incidence of Colorectal Adenoma (Cohort and Case-Control Studies)a

Study, Year
(Reference)		 Source of Abstracted Data Methods for Selecting Confounders Confounders Individual Study Estimate RR
(95% CI)		 Index of Heterogeneity and Pooled Estimate; RR
(95% CI)
Cohort studies: regular aspirin use (>2-3 d per week for >1 y) and risk for adenomas
Giovannucci, et al., 199426 Table 4
(p. 244)		 A priorib Age; sex (men); family history of CRC; pack-years of smoking; BMI; physical activity levels; dietary intake of fat, meat, calcium, alcohol, and vitamin D 0.65 (0.42-1.02)  
Chan, et al., 200439 Table 3
(p. 161)		 A priori and stepwise model-based selectionb Age; sex (women); pack-years of smoking; BMI; physical activity levels; history of CRC in sibling or parent; alcohol intake; postmenopausal HRT; meat, calcium, and vitamin intake 0.73 (0.61-0.87)  
  I2 = 0
RR = 0.72 (0.61-0.85)
Case-control studies: regular aspirin use and risk for adenomas
Morimoto, et al., 200234 Table 3
(p. 1016)		 Backwards stepwise model-based selectionb Age, sex, BMI, HRT, pack-years of smoking, alcohol consumption 0.70 (0.50-1.10)  
Kahn, et al., 199837 Table 3
(p. 307)		 Stepwise model-based selectionb Age; education; race; gallbladder status; BMI; exercise; smoking; alcohol and coffee consumption; multivitamin use; family history of CRC; dietary intake of eggs, vegetables, and meat 0.97 (0.89-1.06)
Sample of men		  
Kahn, et al., 199837 Table 3
(p. 307)		 Stepwise model-based selectionb Same as in men, plus parity, HRT, and menopausal status 0.85 (0.77-0.95)
Sample of women		  
Suh, et al., 199319 Table 2
(p. 1174)		 A priori and stepwise model-based selectionb Age, sex, residence, and level of education 0.61 (0.26-1.40)  
García-Rodríguez and Huerta-Alvarez, 200035 Table 5
(p. 380)		 Stepwise model-based selectionb Age, sex, ischemic heart disease, constipation 0.90 (0.60-1.30)  
Logan, et al., 199333 Table 2
(p. 286)		 A priori and stepwise model-based selectionb Age- and sex-matched case-patients and controls 0.55 (0.30-1.10)  

a. BMI = body mass index; CRC = colorectal cancer; HRT = hormone replacement therapy; RR = relative risk.
b. Multiple logistic regression model.

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