Factors associated with increased incidence of pneumonia in chickenpox
| Country | [Ref.] | Factor | OR (95% CI) |
| UK | 16 | Chest symptoms at presentation | 28.1 (4.1–19.1) |
| USA | 26 | ||
| USA | 27, 28 | Ever smoker | 8.9 (4.1–10.1) |
| UK | 16, 29 | ||
| USA | 28 | Spots n >100 | 17.0 (2.1–134.6) |
| UK | 16 | Any contact with chicken pox | 4.8 (1.04–22.1) |
| UK | 16 | History of contact with own child | 7.8 (1.85–33.2) |
| USA | 28 | Pregnancy (third trimester) | 4.0 (1.4–11.9) |
Data from referenced studies were merged to calculate the odds ratio (OR)
ref.: reference
CI: confidence interval