Summary of findings for the main comparison.
Calcium supplementation/fortification compared to control for prevention of primary hypertension
| Calcium supplementation/fortification compared to control for prevention of primary hypertension | ||||
| Patient or population: People who may be at risk for primary hypertension Settings: US (8), New Zealand (3), and one each in The Netherlands, Belgium and Denmark, Guatemala and Iran Intervention: Calcium supplementation/fortification Comparison: Placebo | ||||
| Outcomes | Illustrative blood pressure in control groupb | Mean Difference in mmHg (95% CIa) | No of Participants (studies) | Quality of the evidence (GRADE)c |
| Systolic blood pressure | 115.64 | 1.43 lower (2.15 lower to 0.72 lower) | 3048 (16 studies) | ⊕⊕⊕⊕ high |
| Diastolic blood pressure | 78.20 | 0.98 lower (1.46 lower to 0.50 lower) | 2947 (15 studies) | ⊕⊕⊕⊕ high |
| Systolic blood pressure. Dose less than 1000 mg a day | 101.60 | 0.08 higher (2.16 lower to 2.32 higher) | 263 (2 studies) | ⊕⊕⊕⊝ moderate1 |
| Systolic blood pressure. Dose between 1000 mg a day and less than 1500 mg a day | 122.43 | 1.14 lower (2.01 lower to 0.27 lower) | 2435 (8 studies) | ⊕⊕⊕⊕ high |
| Systolic blood pressure. Dose 1500 mg a day or more | 112.85 | 2.79 lower (4.71 lower to 0.86 lower) | 350 (7 studies) | ⊕⊕⊕⊝ moderate1 |
| Systolic blood pressure. Less than 35 years of age | 113.25 | 2.11 lower (3.58 lower to 0.64 lower) | 399 (7 studies) | ⊕⊕⊕⊝ moderate1 |
| Systolic blood pressure. 35 years or older | 121.43 | 0.96 lower (1.83 lower to 0.09 lower) | 2649 (9 studies) | ⊕⊕⊕⊕ high |
| aCI: Confidence interval; bEstimated using Comprehensive Meta‐Analysis Software Software; cGRADE Working Group grades of evidence | ||||
| High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||
1. Small number of participants and studies.