Table 2

Age- and sex-adjusted means of serum IGF-I, IGFBP-3, and molar ratio (IGF-I:IGFBP-3), by lifestyle and anthropometric variables, Singapore Chinese Health Study

PredictorNumber of subjectsIGF-I (ng/ml)IGFBP-3 (ng/ml)Molar ratio (IGF-I:IGFBP-3)*1000
BMI (kg/m2)
 Quartile
 1 <20.951591273800120
 2 <23.051581373935124
 3 <24.251611303899121
 4 ≥24.251601364080121
P for linear trend0.250.0060.95
Current cigarette smoking and alcohol intakea
 No/no4291343963122
 No/yes891273921115
 Yes/no791383875130
 Yes/yes411193694117
P for alcohol effectb0.060.350.04
P for smoking effectb0.960.140.11
P for interactionc0.300.450.46
Physical activity
 No weekly vigorous or strenous sports and ≥9 h of sitting/day941454068128
 Others5441313904120
P for physical activity0.020.080.08
Weekly intake of vitamin/mineral supplements
 No5891313915120
 Yes491524097132
P for supplement intake0.010.140.04
  • a Combined effect of current cigarette smoking and current intake of at least 1 alcoholic drink/month.

  • b Ps for current smoking and alcohol intake, respectively, based on three-way analysis of covariance with current alcohol intake and smoking status as independent variables, and gender and age as covariates.

  • c P for interaction term, based on four-way analysis of covariance with current alcohol intake and smoking status, as well as their interaction terms as independent variables, and gender and age as covariates.