Evaluation of Guillain-Barré Syndrome (GBS) following Respiratory Syncytial Virus (RSV) Vaccination Among Adults 65 Years and Older
|
Design
|
Self-controlled case series (SCCS) post-market analysis
N= 3,226,689 doses
|
Objective
|
To assess the risk of GBS following RSV vaccinations in adults aged 65 years and older
|
Study Groups
|
RSVPreF3+AS01 (AREXVY®; n= 2,202,247)
RSVPreF (ABRYSVO®; n= 1,024,442)
|
Inclusion Criteria
|
Medicare Fee-for-Service (FFS) (Parts A, B and D) beneficiaries aged 65 years and older; enrolled on date of first observed RSV vaccination and during 1-year prior to vaccination; incident GBS case during the observation period (i.e., no GBS event in the clean window); vaccinated with either RSVPreF3+AS01 or RSVPreF prior to Jan 28, 2024
|
Exclusion Criteria
|
Not disclosed
|
Methods
|
Data was collected from Medicare FFS beneficiaries for the incidence of GBS, either during early-season (through April 6, 2024) or end-of-season (through July 13, 2024) vaccination. Patients were observed for 90 days after vaccination, with the incidence of GBS being categorized as within the risk interval (days 1-42) or control interval (days 43-90). GBS was determined inpatient- primary position only, through billing codes (i.e., ICD-10-CM DGN G61.0).
|
Duration
|
Study duration: May 2023 to July 2024
Risk interval: 1 to 42 days
Control interval: 43 to 90 days
|
Outcome Measures
|
Incidence of GBS (total); GBS cases during the 90-day observation period; GBS cases after applying clean window restriction; positive predictive value and attributable risk of GBS; incidence rate ratio of GBS
|
Baseline Characteristics
|
|
Early-Season SCCS Analysis
|
End-of-Season SCCS Analysis
|
|
Vaccine
|
RSVPreF3+AS01 |
RSVPreF |
RSVPreF3+AS01 |
RSVPreF |
|
Doses administered |
~872,000 |
~456,000* |
2,2,00,000* |
1,000,000* |
|
GBS Cases
Total GBS cases**
90-day observation period
After applying clean window restriction
|
160
105
55
|
92
74
36
|
236
119
<70
|
130
89
<50
|
|
GBS cases qualifying for SCCS analysis |
11 |
17 |
56 |
39 |
|
*Medicare beneficiaries that received one RSV vaccination and eligible for early- and end-of-season SCCS analysis are presented. Product-specific and total dose counts may not equal due to rounding
** Days per study period: Early season RSVPreF3+AS01= 339; early season RSVPreF3= 311; end of season RSVPreF3+AS01= 437; end of season RSVPreF3= 409
|
Results
|
Endpoint
|
SCCS qualifying cases (N= 95) |
Total GBR medical records
Chart-confirmed GBS case (Level 1,2,3)
Insufficient evidence/not a case (level 4,5)
Records not returned
|
95
51
24
20
|
|
Positive predictive value (PPV) |
95% Confidence Interval (CI) |
|
|
Overall PPV of GBS
Risk interval*
Control interval*
|
68.0%
62.3%
81.8%
|
56.8% to 77.5%
48.8% to 74.1%
61.5% to 92.7%
|
|
|
|
Incidence rate ratio (IRR) |
95% CI |
|
|
Early vs. end-of-season GBS
RSVPreF3+AS01
RSVPreF3
|
2.46
2.02
|
1.19 to 5.08
0.93 to 4.40
|
|
|
|
Attributable risk (AR) |
95% CI |
|
|
AR per 100,000 doses
RSVPreF3+AS01
RSVPreF3
|
0.65
0.90
|
0.18 to 1.12
-0.02 to 1.81
|
|
|
AR Per 100,000 person-years
RSVPreF3+AS01
RSVPreF3
|
5.71
7.82
|
1.61 to 9.80
-0.17 to 15.81
|
|
|
*Cases in risk and control intervals are the average number of true cases in the multiple imputation process Small cell sizes <11; suppressed to protect patient confidentiality
|
Adverse Events
|
See Results
|
Study Author Conclusions
|
The study suggests an increased risk of GBS following RSV vaccinations, consistent with pre-licensure trials and VAERS data, although the risk is rare. There was no difference in risk with concomitant vaccinations.
|
InpharmD Researcher Critique
|
As diagnosis was confirmed via diagnostic codes, misclassifications may have occurred. Data was recorded through chart reviews and not a controlled setting. Therefore, results may be impacted by confounding variables. |