Table 4.
Interaction of BMI with the Effect of Calcium Supplementation on Adenoma Outcomes
| Placebo | Calcium | RR (95% CI)3 within BMI Strata |
Pint4 | |||
|---|---|---|---|---|---|---|
| N/Total (%)1 | RR (95% CI)2 | N/Total (%)1 | RR (95% CI)2 | |||
| CPPS – Adenoma Recurrence5: | ||||||
| BMI6 <25 | 86/146 (58.9) | 1.0 (Ref) | 59/128 (46.1) | 0.83 (0.65-1.07) | 0.84 (0.66-1.07) | 0.49 |
| BMI 25-<30 | 96/204 (47.1) | 0.80 (0.64-1.00) | 80/185 (43.2) | 0.73 (0.58-0.92) | 0.90 (0.72-1.13) | |
| BMI ≥30 | 45/97 (46.4) | 0.79 (0.60-1.05) | 53/120 (44.2) | 0.74 (0.57-0.97) | 0.95 (0.68-1.31) | |
| CPPS - High Risk Findings7: | ||||||
| BMI <25 | 41/142 (28.9) | 1.0 (Ref) | 15/122 (12.3) | 0.47 (0.27-0.82) | 0.48 (0.28-0.82) | 0.03 |
| BMI 25-<30 | 34/200 (17.0) | 0.62 (0.41-0.95) | 27/178 (15.2) | 0.52 (0.33-0.82) | 0.82 (0.51-1.33) | |
| BMI ≥30 | 17/94 (18.1) | 0.60 (0.34-1.05) | 22/118 (18.6) | 0.66 (0.40-1.08) | 1.12 (0.59-2.11) | |
| VCPPS – Adenoma Recurrence5: | ||||||
| BMI <25 | 44/74 (59.5) | 1.0 (Ref) | 21/66 (31.8) | 0.56 (0.38-0.82) | 0.54 (0.36-0.80) | 0.001 |
| BMI 25-<30 | 79/172 (45.9) | 0.79 (0.60-1.04) | 69/164 (42.1) | 0.73 (0.55-0.97) | 0.95 (0.74-1.22) | |
| BMI ≥30 | 59/133 (44.4) | 0.79 (0.59-1.05) | 83/151 (55.0) | 0.94 (0.72-1.24) | 1.21 (0.95-1.54) | |
| VCPPS - High Risk Findings7: | ||||||
| BMI <25 | 16/71 (22.5) | 1.0 (Ref) | 8/66 (12.1) | 0.57 (0.26-1.25) | 0.58 (0.26-1.28) | 0.04 |
| BMI 25-<30 | 22/172 (12.8) | 0.56 (0.31-1.02) | 22/162 (13.6) | 0.63 (0.35-1.14) | 1.13 (0.64-1.97) | |
| BMI ≥30 | 19/130 (14.6) | 0.67 (0.36-1.25) | 34/149 (22.8) | 1.01 (0.58-1.75) | 1.52 (0.90-2.56) | |
Abbreviations: CCPS, Calcium Polyp Prevention Study; VCPPS, Vitamin D/Calcium Polyp Prevention Study; BMI, body mass index in kg/m2; Pint, interaction p-value; RR, relative risk; 95% CI, 95% confidence interval.
Models are adjusted for age (continuous), sex (male/female), race/ethnicity (non-Hispanic white/other), smoking status (never/former/current), baseline serum 25(OH)D.
Number of participants with outcome/total number of participants (% of participants with outcome).
Relative risks compared to referent group (BMI<25, assigned to placebo).
Relative risks for calcium supplementation within each BMI stratum.
Interactions (calcium/placebo × BMI category) were assessed with the use of Wald tests and multiplicative interaction terms.
Adenoma recurrence refers to the development of ≥1 adenomas of any type.
Median BMI values for the three categories are: 22.9, 27.3 and 33.4 (CPPS); 23.3, 27.5, 34.2 (VCPPS)
High-risk findings refers to the development of ≥1 advanced adenoma or ≥3 adenomas of any type. Advanced adenomas are defined as those with cancer, high-grade dysplasia, >25% villous features, or a diameter ≥1 cm.