Table 3.
Summary of findings with certainty of evidence (GRADE [28]).
| Outcomes | Effect a | Number of Participants (Number of Studies) | Certainty of Evidence (GRADE) [28] |
|---|---|---|---|
| Outpatient clinic visits for any respiratory cause | All three studies observed a positive association between wildfire smoke and clinic visits for respiratory problems | 9977 (3) [15,33,35] | Low All observational studies, some concerns about risk of bias. |
| Outpatient clinic visits for asthma exacerbation | No significant effect of wildfire smoke on asthma clinic visits with only one of three studies showing a positive association | 9977 (3) [15,33,35] | Very low All observational studies, some concerns about risk of bias. |
| ED visits for any respiratory cause | Five of eight studies noted a positive association between wildfire smoke exposure and respiratory ED visits; two showed no difference and one showed a negative association | 557,454 (8) [23,33,34,36,38,39,40,42] | Moderate Observational studies however participant numbers are high and some evidence of dose–response relationship |
| ED visits for asthma exacerbation | No significant association between wildfire exposure and ED asthma visits with three of eight studies showing a positive association and five no association | 557,454 (8) [23,33,34,36,38,39,40,42] | Moderate Observational studies however participant numbers are high and some evidence of dose–response relationship |
| Hospitalization for any respiratory cause | Three of four studies showed a positive association between wildfire smoke and respiratory hospitalizations and one no association | 13,258 (4) [30,31,33,38] | Moderate Some evidence of dose response |
| Hospitalization for asthma exacerbation | No significant association between asthma hospitalizations and wildfire smoke, with two of four studies showing a positive association and two no association | 13,258 (4) [30,31,33,38] | Moderate Some evidence of dose response |
| Any respiratory symptoms or self-reported diagnoses: dry or wet cough, asthma exacerbation, bronchitis | No clear association between wildfire smoke and respiratory symptoms shown with one study positive and one smaller study showing no association | 1330 (2) [15,16] | Very low Risk of bias with exposure characterization and outcome assessment |
| Itchy/watery eyes, nasal congestion or sneezing, rhinitis and sore throat | Strong association between eye, nose and throat symptoms and wildfire smoke exposure in two studies | 1330 (2) [15,16] | Low Risk of bias for exposure characterization |
a A pooled estimate was not available for any of the outcomes due to the significant heterogeneity across studies. Instead, a qualitative synthesis of the evidence is reported.