Table 2.
Outcomes of studies included in the meta-analysis.
| All-cause pneumoniaa | All-cause mortality | |||||
|---|---|---|---|---|---|---|
| 1st Author (publication year) | Intervention | Vaccine status and ascertainment | Incidence(per person years)b | RR (95% CI)c | N (%) | RR (95% CI)c |
| Chan (2012) | FV+PV | Record of nursing home showed the vaccination status of each resident. | n/a | n/a | 42 (17.1) | FV+PV vs. FV: aHR = 0.54 (0.35–0.84) |
| FV | n/a | n/a | 57 (27) | |||
| Chang (2012) | FV+PV | Record of National Health Insurance showed re-imbursement of influenza vaccination during the free influenza vaccine period. | 2.1% (0.021 per person years) | FV+PV vs. FV: aOR = 0.85 (0.69–1.05) | 1.30% | FV+PV vs. FV: aOR = 0.74 (0.57–0.96) |
| FV | 2.4% (0.024 per person years) | 1.70% | ||||
| Kawakami (2010) | FV+PV | In this RCT, the participants received seasonal influenza vaccine in 2005, and received 23-valent PV in 1-month interval after FV in FV plus PV group. | 8.6% (0.086 per person year) | FV+PV vs. FV: aHR = 0.73 (0.44–1.23) | 23 (5.9) | n/a |
| FV | 10.5% (0.105 per person year) | 25 (6.5) | ||||
| Hung (2010) | FV+PV | In this prospective study, all participants except the 23-valent PV-alone group and the unvaccinated group were received intramuscular 2007–2008 and 2008–2009 trivalent FV. | 7.3% (0.073 per person years) | FV+PV vs. FV: aHR = 0.76 (0.62–0.93) | n/a | Vaccinated vs. unvaccinated: aHR = 0.65 (0.55–0.77) FV+PV vs. FV: aHR = 0.86 (0.64–1.16) |
| FV | 9.5% (0.095 per person years) | n/a | Vaccinated vs. unvaccinated: HR = 0.78 (0.61–1.0) | |||
| Christenson (2004) | FV+PV | In this prospective study, participants received trivalent FV alone, 23-valent PV or both FV and PV. | 1.6% (0.016 per person years) | Vaccinated vs. unvaccinated: aOR = 0.71 (0.65–0.75) FV+PV vs. FV: aOR = 0.756 (0.676–0.844) |
n/a | Vaccinated vs. unvaccinated: aOR = 0.29 (0.06–1.31) FV+PV vs. FV: aOR = 0.414 (0.047–3.64) |
| FV | 2.14% (0.0214 per person years) | Vaccinated vs. unvaccinated: aOR = 0.94 (0.86–1.02) | n/a | Vaccinated vs. unvaccinated: aOR = 0.70 (0.15–3.21) | ||
| Honkanen (1999) | FV+PV | Records from local health centers in 23 administrative districts in northern Finland (cohort I) showed trivalent FV and 23-valent PV or trivalent FV alone in autumn 1992, and this was extended to a further 12 districts (cohort II) in 1993. | 0.74% (0.0074 per person years) | FV+PV vs. FV: Risk ratio = 1.2 (0.9–1.5)d | n/a | n/a |
| FV | 0.63% (0.0063 per person years) | n/a | ||||
FV, influenza vaccination; PV, pneumococcal vaccination; RR, relative risk; aHR, adjusted hazard ratio; aOR, adjust odds ratio; n/a, not available.
Pneumonia refer to ICD-9-CM: 480–486 or ICD-10-CM: J12–18.
The incidence of all-cause pneumonia were converted to per person years for all studies.
A0 RR > 1 indicates that influenza + pneumococcal vaccination is associated with a higher pneumonia or all-cause mortality rate than influenza vaccination alone, whereas an RR < 1 indicates that dual vaccination is associated with a lower pneumonia or all-cause mortality rate than influenza vaccination alone. A RR = 1 indicates the rates are similar between the 2 treatment groups.
The definition of RR in Honkanen et al.19 was irrelevant to either OR or HR. The RR in this study was calculated based on the ratio between outcome rates per 1,000 person-years of the influenza+pneumococcal group and the influenza alone group.