Quality assessment of included studies using the Newcastle-Ottawa Scale
| Study | Selection (0–4) | Comparability (0–2) | Outcome (0–3) | Total Score (0–9) | Quality rating |
|---|---|---|---|---|---|
| Duggan et al. [17] (2014) | 4 | 2 | 3 | 9 | High |
| Fordyce et al. [18] (2006) | 4 | 2 | 2 | 8 | High |
| Gay-Bellile et al. [19] (2016) | 4 | 2 | 3 | 9 | High |
| Heaphy et al. [20] (2007) | 4 | 2 | 3 | 9 | High |
| Lu et al. [21] (2011) | 4 | 2 | 3 | 9 | High |
| Shen et al. [23] (2012) | 4 | 2 | 3 | 9 | High |
| Simpson et al. [22] (2015) | 4 | 2 | 3 | 9 | High |
| Svenson et al. [24] (2008) | 4 | 2 | 2 | 8 | High |
| Vodenkova et al. [25] (2020) | 4 | 2 | 2 | 8 | High |