Table 3.
Number of articles and number of patients studied, based on study methodology, country income, and geographic region
| Number of studies | Number of patients | |
|---|---|---|
| Methodology | ||
| Case report | 6 | 1 for each |
| Case series | 5 | 5, 5, 7, 16, 145 |
| Case–control | 1 | 157 |
| Cohort | 22 | 10–1877* |
| Cross-sectional | 27 | 8–6049* |
| Longitudinal observational | 1 | 51 |
| Qualitative | 3 | 24, 43, 114 |
| RCT | 1 | 72 |
| Level of income | ||
| High | 46 | 1–2286* |
| Upper middle | 14 | 1–6049* |
| Lower middle | 1 | 1 |
| Low | 2 | 1 for each |
| Region | ||
| Europe and Central Asia | 40 | 1–2286* |
| North America | 9 | 1–570* |
| East Asia and Pacific | 9 | 26–6049* |
| The Middle East and North Africa | 2 | 52, 1529 |
| South Asia | 1 | 1 |
| Sub-Saharan Africa | 2 | 1 for each |
| Multinational | 3 | 16, 234, 2113 |
*Range