Table 12.
GRADE assessment – O3 annual exposure and respiratory mortality.
| Domain | Judgement | Down/Up Grade |
|---|---|---|
| Limitations in studies | Only 4 studies; all rated low or moderate risk of bias | No downgrading |
| Indirectness | All studies included the desired population, exposures and outcomes | No downgrading |
| Inconsistency | The 80% prediction interval included 1 & PI > 2 × CI (Fig. 7). Substantial heterogeneity amongst small number of studies. | Downgrade one level |
| Imprecision | The number of person years in the included studies was greater than 940 000 | No downgrading |
| Publication Bias | No analysis of publication bias – too few studies (n = 4) | No downgrading |
| Large Effect Size | Summary RR = 0.99 | No upgrading |
| Plausible confounding towards null | Confounding direction unknown but precision may be affected. | No upgrading |
| Dose-response relation | A linear dose–response relationship was assumed in all studies. 95% CI for linear RR included 1. None of the studies reported dose–response relationship. | No upgrading |
| GRADE conclusion | Downgrade one level and no upgrade | LOW CERTAINTY EVIDENCE MEAN RR UNADUSTED FOR CO-POLLUTANTS EQUALS 0.99 PER 10μ/m3 |