Assessment of bias in single-city studies and in pooled estimates for all-cause mortality and cause-specific mortality
| All-cause | Cardiovascular | Respiratory | |||
|---|---|---|---|---|---|
| No Adjustment* | 1.04 (0.52 to 1.56) | 0.84 (0.41 to 1.28) | 1.51 (1.01 to 2.01) | ||
| Single-city bias† | |||||
| WHO region | Amr A | Amr A | Amr B | Eur A | Amr B |
| p Value Begg | 0.14 | 0.57 | 0.32 | 0.35 | 0.32 |
| p Value Egger | 0.003 | 0.42 | NA | 0.32 | NA |
| # Estimates | 5 | 6 | 2 | 6 | 2 |
| #Trim and fill | 8 | 7 | 3 | 7 | 3 |
| Single-city‡ | 0.97 (0.46 to 1.48) | 0.78 (0.35 to 1.21) | 1.00 (0.73 to 1.27) | ||
| Multicity bias§ | |||||
| p Value Begg | 0.81 | 0.09 | 0.46 | ||
| p Value Egger | 0.36 | 0.32 | 0.52 | ||
| # Estimates | 8 | 6 | 8 | ||
| # Trim and fill | 8 | 8 | 8 | ||
| Pooled single and multicity¶ | 0.97 (0.46 to 1.48) | 0.57 (0.09 to 1.05) | 1.00 (0.73 to 1.27) | ||
*Random effects summary estimate (95% CI) per 10 μg/m3 without adjustment for small study bias.
†Analysis of bias in single-city studies by WHO region (where found): Begg's test p value, Egger's test p value, number of estimates prior to application of ‘trim and fill’ technique, number of estimates after application of ‘trim and fill’ technique.
‡Overall summary estimate calculated after application of ‘trim and fill’ technique to single-city estimates by WHO region.
§Bias between pooled single-city estimates and multicity estimates, Begg's test p value, Egger's test p value, number of estimates prior to application of the trim and fill’ technique, number of estimates after application of the ‘trim and fill’ technique.
¶Overall summary estimate after application of the ‘trim and fill’ technique to single-city estimates within WHO region and between pooled single-city estimates and multicity estimates.