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Global Evidence for the Use of Calcium for PE/E Prevention Jeffrey Michael Smith, MD, MPH Jhpiego / Johns Hopkins University Maternal Health Team Leader MCHIP Kathmandu, 9 December 2013
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2 Pre-eclampsia Quick reminder: Blood pressure ≥ 140 / 90 Proteinuria In a pregnant woman ≥ 20 weeks or greater, with no pre-pregnancy history of pre-eclampsia
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Dietary modification program in Sydney RHJ Hamlin Lancet 1952
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Experience in Ethiopia Hamlin RHJ. Prevention of pre-eclampsia. Lancet 1962;1:864-865
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Pre-eclampsia and dietary calcium Low incidence of pre-eclampsia noted in Guatemala (Belizan 1980) Postulated due to high calcium diets Belizan JM, Villar J. The relationship between calcium intake and edema, proteinuria, and hypertension-gestosis: an hypothesis. American Journal of Clinical Nutrition 1980;33:2202-10.
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Calcium supplementation among low calcium intake women: WHO randomized trial Villar J, Abdel-Aleem H, Merialdi M, Mathai M, Ali M, Zavaleta N, Purwar M, Hofmeyr GJ, thi Nhu Ngoc N, Campódonico L, Landoulsi S, Carroli G, Lindheimer M et al. Am J Obstet Gynecol 2006;194: 639-649 ↓ Revised Systematic Review: Hofmeyr GJ, Lawrie TA, Atallah ÁN, Duley L. Cochrane Database of Syst Reviews 2010
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Calcium vs Placebo: Pre-eclampsia
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Calcium vs Placebo: Proteinuria
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Calcium vs Placebo: Eclampsia
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Calcium vs Placebo: Maternal Death
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Calcium vs Placebo: Maternal death / severe morbidity
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Calcium vs Placebo: Preterm birth
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Calcium and pre-eclampsia Epidemiological association of dietary calcium deficiency with pre-eclampsia / eclampsia Calcium supplementation reduces: Pre-eclampsia by 64% (but only 8% in WHO trial) Severe morbidity by 20% Preterm birth by 10% (borderline significance) Increases HELLP syndrome
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Hypothesis: Calcium supplementation in 2 nd half of pregnancy: ↓ blood pressure (↓ vascular tone) ↓ serious complications related to hypertension No effect on ‘underlying pre-eclampsia process’ ↓ early deliveries in Ca group → more women went on to develop HELLP syndrome To prevent underlying pre-eclampsia process may need adequate calcium from before pregnancy Hofmeyr G, Duley L, Atallah A.Hofmeyr G, Duley L, Atallah A. Dietary calcium supplementation for prevention of pre-eclampsia and related problems: a systematic review and commentary. BJOG. 2007; 114: 933-943
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Based on this evidence: World Health Organization recommends (2011) calcium supplementation with 1.5 to 2g calcium daily to pregnant women with low dietary calcium intake BUT: Large dose difficult to implement May be unnecessarily large, or even harmful
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Daily intake of calcium per capita in developing/developed countries (FAO, 1990) REGIONCALCIUM (mg) World472 Developed countries860 Developing countries346 Africa 363 Latin America499 Near East498 Far East352 Others402 About 500 mg
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Cochrane methodology Primary inclusion criteria: Calcium supplementation <1g without co-supplements Secure allocation concealment (low risk of bias) Double blinding with placebo If the above criteria failed to produce adequate data, we planned to include: quasi-randomized trials trials without placebo control trials of multiple supplements, with appropriate caution in the interpretation
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Cochrane review: Low dose calcium
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Results All trials used 500mg daily Consistent 60% reduction in pre-eclampsia across all 9 trials (2234 women) Significant reduction for all high quality trials; and all trials of calcium alone An unexpected finding in one high quality trial of calcium plus antioxidants commencing at 8-12 weeks of pregnancy was a trend to reduced miscarriage (1/29 versus 8/31, RR 0.06, 95% CI 0.00 to 1.04).
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Conclusions Available evidence supports the probable effectiveness of low-dose calcium supplementation Low quality of evidence requires further research If the WHO recommendation of 1.5 to 2g calcium daily is not achievable, it is reasonable to use a lower dosage (eg 500mg daily)
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The Calcium and Pre-eclampsia (CAP) study (WHO Study A65750) Randomized trial: calcium 500mg daily vs placebo commencing before conception till 20 weeks All women receive routine calcium in second half of pregnancy Participants: women with previous pre-eclampsia who intend to conceive If effective, next step will be food fortification Analysis plan includes measuring effect on conception and miscarriage.
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22 THANK YOU
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