Table 3.
Subgroup analysis of the association between vaccination and dementia risk.
| Subgroups | Studies | HR (95%CI) | P overall effect | Heterogeneity (I 2, PH ) | Effects model |
|---|---|---|---|---|---|
| Total | 17 | 0.65 (0.60, 0.71) | <0.001 | 91.8%, <0.001 | Random |
| Vaccine type | |||||
| Influenza | 9 | 0.74 (0.63, 0.87) | <0.001 | 97.7%, <0.001 | Random |
| Herpes zoster | 3 | 0.69 (0.67, 0.72) | <0.001 | 10.8%, 0.339 | Fixed |
| Tdap† | 3 | 0.69 (0.58, 0.82) | <0.001 | 97.1%, <0.001 | Random |
| Bacillus Calmette–Guerin | 3 | 0.42 (0.17, 1.07) | 0.069 | 91.5%, <0.001 | Random |
| Pneumonia | 2 | 0.68 (0.41, 1.13) | 0.137 | 92.8%, <0.001 | Random |
| Poliomyelitis | 2 | 0.78 (0.44, 1.40) | 0.406 | 73.6%, 0.052 | Random |
| Other | 1 | 0.78 (0.74, 0.81) | <0.001 | 21.0%, 0.256 | Fixed |
| Gender | |||||
| Male | 5 | 0.66 (0.58, 0.74) | <0.001 | 56.8%, 0.055 | Random |
| Female | 5 | 0.67 (0.63, 0.72) | <0.001 | 0.0%, 0.911 | Fixed |
| Age | |||||
| <70 years | 5 | 0.74 (0.66, 0.84) | <0.001 | 72.6%, 0.001 | Random |
| ≥70 years | 7 | 0.64 (0.57, 0.72) | <0.001 | 94.6%, <0.001 | Random |
| Dose ‡ | |||||
| 1 vaccine | 3 | 1.03 (0.98, 1.08) | 0.229 | 6.9%, 0.342 | Fixed |
| 2-3 vaccine | 3 | 0.87 (0.74, 1.02) | 0.088 | 88.9%, <0.001 | Random |
| ≥4 vaccine | 4 | 0.51 (0.32, 0.80) | 0.003 | 98.7%, <0.001 | Random |
| Dementia type | |||||
| Alzheimer’s disease | 10 | 0.63 (0.55, 0.72) | <0.001 | 87.9%, <0.001 | Random |
| Vascular dementia | 1 | 0.60 (0.45, 0.80) | <0.001 | NA | NA |
| Other dementia | 1 | 0.69 (0.62, 0.75) | <0.001 | NA | NA |
HR, hazard risk; OS, overall survival; DFS, disease-free survival; NA, not applicable; Tdap: tetanus, diphtheria, pertussis.
†This analysis group included cohorts that reported receiving one or two of the Tdap vaccines.
‡ Only the studies on influenza vaccines supported dose grouping.