Pooled prevalence ratio of high serum Legionella antibody level in dental healthcare workers
| Analysis | Studies | Cochran’s Q-test | Prevalence ratio | 95% CI |
| Pooled analysis | All (8) | 28.72* | 1.66 | 0.85 to 3.22 |
| Pooled analysis adjusted for study quality | All (8) | 16.13* | 1.51 | 0.55 to 4.15 |
| Dentists | 6 | 24.96* | 1.45 | 0.54 to 3.89 |
| Dental assistants | 2 | 9.47* | 2.89 | 0.39 to 21.27 |
| Dental students† | 2 | 2.95 | 0.95 | 0.56 to 1.62 |
| Studies published before 1998 | 4 | 9.99* | 2.63* | 1.12 to 6.18 |
| Studies published after 1998 | 4 | 9.61* | 0.99 | 0.38 to 2.58 |
Estimates assessed with and without adjustment for study quality. Subgroup analyses for working categories and for publication year, namely, before/after 1998. This threshold corresponds to the global dissemination of the guidelines for infection control in dental healthcare settings released for the first time by the US Centers for Disease Control and Prevention in 1993.
Included studies: Dentists references.8 18 33 65 66 Dental assistants references.18 66 Dental students references.8 65 Studies published before the year 1995 references.3 18 65 66 Studies published after the year 1995 references.8 32 33
Weighted metaregression with logarithm of prevalence ratio (x-axis), publication year (y-axis: before 1998=1; after 1998=2), inverse of the variance (weight). y=1.68–0.86 x. 95% CI of slope: −2.15 to 0.43. Pooled prevalence ratio for studies published before 1998, 2.27 (95% CI 0.63 to 8.25). Pooled prevalence ratio for studies published after 1998, 0.96 (95% CI 0.07 to 12.68).
*Statistically significant at 95% level.
†Fixed-effects method.