Outcome | Author [Ref] | Crude OR (95% CI) | Adjusted OR (95% CI) | Off-season adjusted OR (95% CI) | Risk of bias |
---|---|---|---|---|---|
Mortality | Â | Â | Â | Â | Â |
All-cause mortality | Â | Â | Â | Â | |
 | Bond et al.1 [25] | 0.79 (0.72–0.87) | 0.73 (0.67–0.81)2 | 0.90 (0.77–1.10)2 | Unclear |
 | Gilbertson3 [24] | – | 0.77 (0.65–0.90)4 |  | High |
 | McGrath [26] | 0.77 (0.76–0.78)5 | 0.71 (0.70–0.72)5 | 0.45 (0.41–0.50)6 | High |
 | Wang [23] | 0.88 (0.73–1.07)7 | 0.49 (0.41–0.59)7 | – | High |
 | Pooled estimate | 0.77 (0.75–0.80), I2 = 10% | 0.68 (0.61–0.76), I2 = 83% | – | – |
Cardiac death # | Â | Â | Â | Â | Â |
 | Gilbertson3 [24] | – | 0.84 (0.71–0.98)4 | – | High |
Infectious death § |  |  |  |  | |
 | Gilbertson3 [24] | – | 0.83 (0.65–1.05)4 | – | High |
Hospitalization | Â | Â | Â | Â | Â |
All-cause hospitalization | Â | Â | Â | Â | |
 | Gilbertson3 [24] | – | 0.95 (0.85–1.07)4 |  | High |
 | Wang [23] | 1.11 (0.96–1.28)7 | 0.80 (0.69–0.94)7 | – | High |
 | Pooled estimate | – | 0.88 (0.74–1.04), I2 = 70% | – | – |
Hospitalization due to influenza or pneumonia | Â | Â | Â | ||
 | Gilbertson3 [24] | – | 0.90 (0.70–1.16)4 |  | High |
 | McGrath [26] | 0.90 (0.87–0.92)5 | 0.84 (0.82–0.84)5 | 0.74 (0.64–0.85)6 | High |
 | Slinin [27] | – | 0.93 (0.86–1.01) | – | High |
 | Wang [23] | 1.30 (1.08–1.56)7 | 0.77 (0.64–0.93)7 | – | High |
 | Pooled estimate | 1.07 (0.75–1.53), I2 = 93% | 0.86 (0.80–0.93), I2 = 58% |  | – |
Hospitalization due to bacteremia, viremia, or septicemia | Â | Â | Â | Â | |
 | Gilbertson3 [24] | – | 0.73 (0.32–1.68)4 | – | High |
Hospitalization due to respiratory infection | Â | Â | Â | Â | |
 | Gilbertson3 [24] | – | 0.87 (0.69–1.09)4 | – | High |
ICU admission | Â | Â | Â | Â | Â |
 | Wang [23] | 0.38 (0.27–0.53)7 | 0.19 (0.14–0.27)7 | – | High |
Other outcomes | Â | Â | Â | Â | Â |
Influenza-like illness | Â | Â | Â | Â | Â |
 | McGrath [26] | 0.93 (0.91–0.95)5 | 0.88 (0.86–0.90)5 | 0.77 (0.68–0.88)6 | High |