TABLE 2.
The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE).
| Outcome | Certainty assessment | No. of patients | Effect | Certainty | |||||||
| Study design | No. of studies | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | Vitamin D | Control | Relative risk (95% CI) |
||
| Mortality | Cohort studies | 8 | Seriousa | Not serious | Seriousb | Not serious | None | 105/976 (10.8%) | 201/1065(18.9%) | RR 0.33(0.23–0.47) | ⊕⊕○○ Low |
| Randomized controlled trials | 8 | Seriousa | Not serious | Seriousb | Seriousd | None | 59/677 (8.7%) | 65/641(10.1%) | RR 0.94(0.69–1.29) | ⊕○○○ Very low | |
| ICU admission | Cohort studies | 2 | Seriousa | Seriouscc | Seriousb | Seriousd | None | 36/575 (6.3%) | 95/460 (20.7%) | RR 0.32(0.08–1.29) | ⊕○○○ Very low |
| Randomized controlled trials | 6 | Seriousa | Seriouse | Seriousb | Seriousd | None | 86/605(14.2%) | 103/562 (18.3%) | RR 0.64(0.38–1.08) | ⊕○○○ Very low | |
| Mechanical ventilation or intubation | Cohort studies | 3 | Seriousa | Not serious | Seriousb | Seriousd | None | 64/536 (11.9%) | 61/232 (26.3%) | RR 0.93(0.55–1.58) | ⊕○○○ Very low |
| Randomized controlled trials | 5 | Seriousa | Not serious | Seriousb | Seriousd | None | 49/331(14.8%) | 69/325 (21.2%) | RR 0.66(0.39–1.10) | ⊕○○○ Very low | |
CI, confidence interval; RR, risk ratio.
aSome do not concern with the method of randomization used/allocation concealment/blinding of participants/blinding of outcome assessment/selective reporting.
bThere were differences in vitamin D dosages and duration.
cI2 = 90%;
dThe confidence interval was not narrow enough for us to be confident that this is the effect or does it reduce and has no effect.
ei2 = 60%. Grades of evidence: High: Further research is very unlikely to change our confidence in the estimate of effect; Moderate: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate; low: 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: Any estimate of effect is very uncertain. The number of plus symbols shows the degree of certainty, more plus symbols indicate a higher degree of certainty.