Interrupted time-series analyses of routine vaccination program for elderly pneumonia patients in Japan; an ecological study using aggregated nationwide inpatient data

Figures & data

Figure 1. The estimated PPSV23 coverage rates of subjects aged ≥65 years in Japan. The estimated coverage rates were calculated based on the number of shipped PPSV23 syringes in each prefecture, information that was provided by Japan MSD (Tokyo, Japan), the manufacturer of PPSV23

Figure 2. Flow-diagram of patient selection. We identified 717,156 patients aged ≥65 years who were hospitalized for pneumonia and treated with antibiotics. Patients without a recorded zip code and those in Iwate, Miyagi and Fukushima prefectures were excluded. Overall, 655,746 eligible pneumonia cases were analyzed

Table 1. Results of segmented linear regression analysis of incidence of hospitalized elderly patients with pneumonia before and after the PPSV23 vaccination program

	Trend in pre-immunization period	Trend change following immunization
All	−0.000060 (−0.0021 to 0.0020), p = .95	−0.0039 (−0.0084 to 0.00064), p = .098
Age (years)
65–84	0.000095 (−0.0018 to 0.0020), p = .92	−0.0040 (−0.0085 to 0.00041), p = .081
≥85	−0.0023 (−0.0046 to 0.000020), p = .057	−0.0031 (−0.0082 to 0.0020), p = .24

Data are shown as regression coefficients (95% CI)

Table 2. Results of segmented linear regression analysis of in-hospital mortality before and after the PPSV23 vaccination program

	Trend in pre-immunization period	Trend change following immunization
All	‐0.0039 (‐0.0050 to ‐0.0027), p < .01	‐0.00099 (‐0.0036 to 0.0016), p = .46
Age (years)
65‐84	‐0.0032 (‐0.0045 to ‐0.0020), p < .01	‐0.0022 (‐0.0051 to 0.00082), p = .16
≥85	‐0.0046 (‐0.0061 to ‐0.0031), p < .01	0.00024 (‐0.0032 to 0.0037), p = .89
CCI
0‐1	−0.0040 (−0.0054 to −0.0026), p < .01	−0.00096 (−0.0043 to 0.0023), p = .57
2‐3	‐0.0038 (−0.0053 to ‐0.0023), p < .01	‐0.0020 (−0.0055 to 0.0014), p = .26
≥4	−0.0018 (−0.0038 to 0.00017), p = .078	−0.011 (‐0.015 to −0.0064), p < .01

Data are shown as regression coefficients (95% CI)

Figure 3. Incidence of admissions for pneumonia among the elderly. The numbers of inpatients in the registered facilities per 100,000 individuals are plotted by month. The predicted incidence calculated from the regression model is also shown (solid line). The period excluded from the analysis is shown as a gray region. The arrow shows the time-point when routine PPSV23 vaccination was started

Figure 4. In-hospital mortality of elderly pneumonia patients. Mortality is plotted by month. The predicted mortality calculated from the regression model is also shown (solid line). The period excluded from the analysis is shown as a gray region. The arrow shows the time-point when routine PPSV23 vaccination was started