(A56) Vaccine patterns among older adults diagnosed with Guillain-Barré Syndrome and matched counterparts with Medicare insurance, 2006-2019

Publication Number: 339

Background: Some vaccines have a small risk of triggering Guillain-Barre Syndrome (GBS), an autoimmune disorder characterized by progressive nerve damage that leads to paralysis. There is no guidance for patients with a history of GBS regarding subsequent vaccine use beyond a CDC warning for patients whose GBS was vaccine-triggered (GBS occurring within 42 days of receiving a vaccine). Patients and providers may consider a prior GBS diagnosis when making decisions about vaccines.

Objectives: To describe vaccine patterns before and after a GBS diagnosis.

Methods: We conducted a matched cohort study using a 20% random sample of fee-for-service Medicare beneficiaries with Parts A, B, and D coverage for years 2006-2019. We identified beneficiaries ≥ age 65 at their first observed GBS discharge diagnosis code (index date) with one year of prior continuous enrollment in Medicare (parts A and B). We matched each patient with GBS to 5 counterparts without GBS on sex, racial and ethnic category, exact age, state of residence, and month of preventive health visits. We identified claims for 12 vaccine types (measles-mumps-rubella, human papillomavirus, and the 10 CDC-recommended vaccines for ages ≥65). We used SMR weights to balance markers of healthcare use and indicators of frailty and comorbidity. We estimated weighted mean cumulative count (wMCC) functions for the number of vaccines received during one year before and year after GBS diagnosis, accounting for competing events and differential follow-up.

Results: We identified 1616 patients with a GBS diagnosis code, of whom 1576 could be matched to 5 counterpart individuals. Patients with GBS had higher wMCC (0.74 vaccines/person) in the one year prior to the index date than matched counterparts (0.71); wMCC difference 0.04 (95% CI 0.01, 0.07). Within one year after the index date, patients with GBS had lower wMCC (0.26) than matched counterparts (0.67); wMCC difference -0.41 (95% CI -0.44, -0.38), and wMCC difference in differences of -0.45. In the subgroup of patients with a GBS diagnosis code, the 1-year post-index wMCC was lower for patients whose index date occurred within 42 days of a vaccine (wMCC 0.13, n=173) compared to those with an index date that was not within this timeframe (wMCC 0.27, n=1403).

Conclusions: Patients identified with GBS received 0.41 fewer vaccines/person within the following year, compared to their matched non-GBS counterparts. The wMCC prior to the index date was higher among GBS patients. Patients with GBS occurring within 42 days of a vaccine received fewer vaccines after diagnosis than patients with a vaccine-GBS gap >42 days. Future work should assess real-world provider recommendations and patient motivations for vaccine use among adults with a history of GBS.