With respect to risk of preterm birth, low-dose calcium noninferior in trial in India but not in trial in Tanzania
By Elana Gotkine HealthDay Reporter
THURSDAY, Jan. 11, 2024 (HealthDay News) — Low-dose calcium supplementation is noninferior to high-dose supplementation for reducing the risk of preeclampsia, according to a study published in the Jan. 11 issue of the New England Journal of Medicine.
Pratibha Dwarkanath, Ph.D., from St. John’s Research Institute in Bangalore, India, and colleagues conducted two independent randomized trials of calcium supplementation in pregnancy in India and Tanzania to assess the noninferiority of a 500-mg daily dose to a 1,500-mg daily dose. The two primary outcomes in each trial were preeclampsia and preterm birth; the noninferiority margins for the relative risks were 1.54 and 1.16, respectively.
Each trial included 11,000 nulliparous pregnant women. The researchers found that the cumulative incidence of preeclampsia was 3.0 and 3.6 percent, respectively, in the 500- and 1,500-mg groups in the India trial (relative risk, 0.84; 95 percent confidence interval, 0.68 to 1.03), and 3.0 and 2.7 percent, respectively, in the Tanzania trial (relative risk, 1.10; 95 percent confidence interval, 0.88 to 1.36); these values were consistent with the noninferiority of the lower dose in both trials. The percentage of preterm births was 11.4 and 12.8 percent in the 500- and 1,500-mg groups, respectively, in India (relative risk, 0.89; 95 percent confidence interval, 0.80 to 0.98), which was within the noninferiority margin; the corresponding percentages were 10.4 and 9.7 percent in the Tanzania trial (relative risk, 1.07; 95 percent confidence interval, 0.95 to 1.21), which exceeded the noninferiority margin.
“The 500-mg dose that we studied as a comparator reduces the pill burden and would be expected to reduce program costs,” the authors write.
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