Summary of findings for the main comparison. Vitamin D versus placebo or no intervention for prevention of cancer in adults.
| Vitamin D versus placebo or no intervention for prevention of cancer in adults | ||||||
|
Patient or population: healthy participants or recruited among the general population; individuals diagnosed with a specific disease in a stable phase or with vitamin D deficiency Settings: outpatients Intervention: vitamin D versus placebo or no intervention | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Control | Vitamin D versus placebo or no intervention | |||||
|
Cancer occurrence Follow‐up: 0.5 to 7 years |
Study population | RR 1.00 (0.94 to 1.06) | 50623 (18) | ⊕⊕⊕⊝ moderatea |
Trial sequential analysis of all vitamin D trials suggests that the futility area is reached after the 10th trial allowing us to conclude that any possible intervention effect, if any, is lower than a 5% relative risk reduction. | |
| 77 per 1000 | 77 per 1000 (72 to 81) | |||||
| Moderate | ||||||
| 28 per 1000 | 28 per 1000 (26 to 30) | |||||
|
Cancer occurrence in trials using vitamin D₃ (cholecalciferol) Follow‐up: 0.5 to 7 years |
Study population | RR 1.00 (0.94 to 1.06) | 49891 (14) | ⊕⊕⊕⊝ moderatea |
Trial sequential analysis of all vitamin D trials suggests that the futility area is reached after the 10th trial allowing us to conclude that any possible intervention effect, if any, is lower than a 5% relative risk reduction. | |
| 77 per 1000 | 77 per 1000 (73 to 82) | |||||
| Moderate | ||||||
| 28 per 1000 | 28 per 1000 (26 to 30) | |||||
|
All‐cause mortality Follow‐up: 0.5 to 7 years |
Study population | RR 0.93 (0.88 to 0.98) | 49866 (15) | ⊕⊕⊝⊝ lowb |
Trial sequential analysis of all trials irrespective of bias risks showed that the required information size had not yet been reached and that the cumulative Z‐curve did not cross the trial sequential monitoring boundary for benefit. | |
| 80 per 1000 | 75 per 1000 (71 to 79) | |||||
| Moderate | ||||||
| 16 per 1000 | 15 per 1000 (14 to 16) | |||||
|
Cancer mortality in trials using vitamin D₃(cholecalciferol) Follow‐up: 5 to 7 years |
Study population | RR 0.88 (0.78 to 0.98) | 44492 (4) | ⊕⊕⊝⊝ lowb |
Trial sequential analysis of all trials irrespective of bias risks showed that the required information size had not yet been reached and that the cumulative Z‐curve did not cross the trial sequential monitoring boundary for benefit. | |
| 29 per 1000 | 25 per 1000 (22 to 28) | |||||
| Moderate | ||||||
| 37 per 1000 | 33 per 1000 (29 to 36) | |||||
|
Adverse events: nephrolithiasis in trials using vitamin D₃(cholecalciferol) combined with calcium Follow‐up: 0.5 to 7 years |
Study population | RR 1.17 (1.03 to 1.34) | 42753 (3) | ⊕⊕⊝⊝ lowb |
Trial sequential analysis of all trials irrespective of bias risks showed that the required information size had not yet been reached and that the cumulative Z‐curve did not cross the trial sequential monitoring boundary for benefit. | |
| 18 per 1000 | 21 per 1000 (18 to 24) | |||||
| Moderate | ||||||
| 1 per 1000 | 1 per 1000 (1 to 1) | |||||
| Health‐related quality of life | See comment | Not investigated. | ||||
| Health economics | See comment | Not investigated. | ||||
| *The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RR: risk ratio | ||||||
| GRADE 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. | ||||||
aDowngraded by one level because of risk of attrition bias
bDowngraded by two levels because of risk of attrition bias and imprecision