Table 4.
Sensitivity analysis of the effect of helmet use on head injuries
| Parameter | No. of studies | OR (95% CI) | Heterogeneity, I2 value, % |
|---|---|---|---|
| Methodologic quality* | |||
| High (score ≥ 18) | 6 | 0.68 (0.55–0.82) | 75.8 |
| Low (score < 18) | 4 | 0.59 (0.35–1.00) | 73.1 |
| Study design | |||
| Case–control | 9 | 0.66 (0.55–0.79) | 75.7 |
| Cohort | 1 | 0.48 (0.48–0.34) | NA |
| Adjusted for confounding | |||
| Yes | 6 | 0.68 (0.55–0.82) | 75.8 |
| No | 4 | 0.59 (0.35–1.00) | 73.1 |
| Adequate outcome assessment | |||
| Yes | 9 | 0.69 (0.58–0.82) | 69.3 |
| No | 1 | 0.43 (0.29–0.64) | NA |
| Adequate exposure assessment | |||
| Yes | 7 | 0.66 (0.54–0.79) | 74.0 |
| No | 3 | 0.63 (0.30–1.34) | 79.7 |
| Adequate selection of cases and controls | |||
| Yes | 8 | 0.66 (0.54–0.79) | 70.0 |
| No | 2 | 0.66 (0.29–1.49) | 89.6 |
Note: CI = confidence interval, NA = not applicable, OR = odds ratio.
*
Overall scores for methodologic quality were determined with use of the Downs and Black checklist (maximum score 28).28