Table 4.
The overall rating for the quality of evidence profile for COVID-19 related health outcomes based on the grading of Recommendations Assessment, Development, and Evaluation (GRADE) working group methodology.
| Certainty assessment |
№ of patients |
Effect |
Certainty |
Importance |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| № of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | Intervention | Control | Relative (95% CI) | Absolute (95% CI) | ||||
| Mortality | ||||||||||||||
| 5 | randomised trials | serious a | not serious | serious b | not serious | none | 19/276 (6.9%) | 25/276 (9.1%) | RR 0.73 (0.42–1.27) | 24 fewer per 1,000 (from 53 fewer to 24 more) | ⨁⨁◯◯ LOW |
CRITICAL | ||
| ICU length of stay | ||||||||||||||
| 3 | randomised trials | not serious | not serious | very serious b | not serious | none | 67 | 69 | – | SMD 0.29 higher (0.05 lower to 0.63 higher) | ⨁⨁◯◯ LOW |
CRITICAL | ||
| Duration of hospital stay | ||||||||||||||
| 4 | randomised trials | serious a | very serious c | serious b | very serious d | none | 170 | 168 | – | SMD 0.23 lower (1.04 lower to 0.58 higher) | ⨁◯◯◯ VERY LOW |
CRITICAL | ||
| Invasive mechanical ventilation incidence | ||||||||||||||
| 3 | randomised trials | not serious | not serious | serious b | not serious | none | 28/132 (21.2%) | 31/134 (23.1%) | RR 0.93 (0.61–1.44) | 16 fewer per 1,000 (from 90 fewer to 102 more) | ⨁⨁⨁◯ MODERATE |
CRITICAL | ||
CI: Confidence interval; RR: Risk ratio; SMD: Standard mean difference.
Explanations.
a
True randomization not done (N = 1).
b
There were differences in the follow up time points to measure the outcomes along with vitamin C dose, route and duration.
c
I2 = 92%.
d
Confidence intervals are not narrow enough for us to be confident enough regarding the true effect of intervention.