Table 1.
Study population | Placebo |
Calcium plus Vitamin D |
HR (95% CI)a | P b | ||
---|---|---|---|---|---|---|
No. cases | IR/1000 | No. cases | IR/1000 | |||
Total sample | 325 | 1.16 | 270 | 0.95 | 0.82 (0.70 to 0.96) | .02 |
Total samplec | 325 | 1.16 | 270 | 0.95 | 0.80 (0.68 to 0.95) | .01 |
Excluding women with <1 year of follow-up | 282 | 1.11 | 233 | 0.90 | 0.81 (0.68 to 0.97) | .02 |
Excluding women with previous breast biopsy | 255 | 1.07 | 185 | 0.77 | 0.72 (0.59 to 0.86) | .001 |
Adherence 50% only | 318 | 1.61 | 260 | 1.31 | 0.82 (0.69 to 0.96) | .02 |
Adherence 80% only | 293 | 1.31 | 236 | 1.06 | 0.81 (0.68 to 0.96) | .02 |
Hazard ratios and 95% confidence intervals were based on Cox proportional hazards models with stratification by age (younger than 60 years, 60 to younger than 70 years, 70 years or older), dietary modification trial participation, hormone replacement treatment trial participation, and prior breast biopsy. CI = confidence interval; HR = hazard ratio; IR/1000 = incidence rate per 1000 person-years.
Two-sided χ2 test.
Analysis adjusted for mammogram and clinical breast exam frequency.