Table 4 Cumulative evidence scale (low is rated 0, moderate 1, and high 2 for each item. The final rating is very low (< 2), low (2–4), moderate (5–6), high (> 6))
Quality | Risk of bias score (mean of the 32-score) | Number of studies (n) | Heterogeneity (I2) | Cumulative sample size | Â |
|---|---|---|---|---|---|
High | > 22 | > 10 | < 30% (low heterogeneity) | > 400 |  |
Moderate | 16–22 | 3–10 | 30–75% (moderate) | 200–400 |  |
Low | < 16 | 0–3 | > 75% (high heterogeneity) | < 200 |  |
Score | Â | Â | Â | Â | Total |