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. 2020 Nov 2;223(3):416–425. doi: 10.1093/infdis/jiaa543

Table 4.

Medicare Fee-for-Service Population Early-Season and End-of-Season Self-Controlled Risk Interval Analysis Results: Odds Ratios and Attributable Risks Among Influenza-Vaccinated Beneficiaries Ages ≥65 Years, 2018–2019a

Number of GBS Cases
Population Risk Window Control Window Odds Ratio Odds Ratio 95% CI P Value Attributable Risk (Per Million Vaccinations) Attributable Risk (Per Million Vaccinations) 95% CI
Early-Season: High-Dose Influenza-Vaccinated Beneficiaries
Risk Window: Days 8–21 Postvaccination
 Claims-based 16 26 1.85 (0.99–3.44) .054 0.98 (−0.02 to 1.82)
 PPV-imputed quantitative bias analysis 11.38 18.47 1.84 (0.78–4.31) .162 0.69 (−0.29 to 1.47)
Risk Window: Days 1–42 Postvaccination
 Claims-based 34 26 1.31 (0.78–2.18) .303 1.07 (−0.97 to 2.99)
 PPV-imputed quantitative bias analysis 24.21 18.58 1.31 (0.65–2.61) .449 0.76 (−1.20 to 2.56)
End-of-Season: High-Dose Influenza-Vaccinated Beneficiaries
Risk Window: Days 8–21 Postvaccination
 Claims-based 18 33 1.64 (0.92–2.91) .093 0.81 (−0.14 to 1.63)
Risk Window: Days 1–42 Postvaccination
 Claims-based 37 33 1.12 (0.70–1.79) .633 0.46 (−1.42 to 2.29)
Early-Season: Influenza-Vaccinated Beneficiariesb
Risk Window: Days 8–21 Postvaccination
 Claims-based 22 42 1.57 (0.94–2.63) .086 0.66 (−0.09 to 1.33)
 PPV-imputed quantitative bias analysis 15.67 29.93 1.56 (0.78–3.15) .211 0.46 (−0.27 to 1.09)
Risk Window: Days 1–42 Postvaccination
 Claims-based 52 42 1.24 (0.82–1.86) .303 0.82 (−0.74 to 2.32)
 PPV-imputed quantitative bias analysis 37.03 30.01 1.24 (0.71–2.14) .449 0.58 (−0.92 to 2.00)
End-of-Season: Influenza-Vaccinated Beneficiariesb
Risk Window: Days 8–21 Postvaccination
 Claims-based 28 53 1.58 (1.00–2.51) .049b 0.72 (0.00–1.36)
Risk Window: Days 1–42 Postvaccination
 Claims-based 63 53 1.19 (0.82–1.71) .354 0.69 (−0.77 to 2.11)

Abbreviations: CI, confidence interval; GBS, Guillain-Barré syndrome; PPV, positive predictive value.

aSeasonality-adjusted results are presented in Supplementary Table S10.

bWith any influenza vaccine (including high-dose influenza vaccine).