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Summary characteristics of studies
| Characteristic | n |
|---|---|
| Location of study | |
| Italy | 4 |
| China | 4 |
| Singapore | 3 |
| France | 2 |
| Colombia | 2 |
| UK | 2 |
| US | 2 |
| Australia | 1 |
| Croatia | 1 |
| Indonesia | 1 |
| Jordan | 1 |
| Oman | 1 |
| Portugal | 1 |
| Romania | 1 |
| Saudi Arabia | 1 |
| Spain | 1 |
| Turkey | 1 |
| Multiple countries | 2 |
|
| |
| Demographic, mean (95% CI), range | |
| Age, years | 42.4 (39.6 to 45.2),a 26–55 |
| Gender, % male | 41.3 (34.6 to 48.5), 15–100 |
Based on 23 studies reporting sufficient information.
