A nationwide Guillain-Barré syndrome epidemiological study in Spain during the COVID-19 years

OBJECTIVE To perform a nationwide epidemiological study of Guillain-Barré syndrome (GBS) in Spain, analysing background incidences and seasonal variation and trying to identify incidence changes during the COVID-19 years. METHODS Observational study collecting all GBS diagnoses from National Epidemiological Surveillance Network (RENAVE) collected by the Ministry of Health. Patients discharged with GBS as main diagnosis and admitted during 2018-2021 were included. Data on the incidence of SARS-CoV-2 infections and vaccinations were obtained from the National Epidemiology Centre. RESULTS In total, 3147 cases were included, 832 in 2018, 861 in 2019, 670 in 2020 and 784 in 2021. Nationwide hospital incidence was 1.78 in 2018, 1.71 in 2019, 1.41 in 2020 and 1.66 in 2021, with an increased frequency in males, elderly population, and in the winter season. Eleven percent of GBS patients needed ventilatory support. GBS and SARS-CoV-2 incidences did not correlate with one another (r=-0.29, p=0.36). GBS incidence decreased during 2020 and during COVID-19 lockdown period in comparison to the same months of 2018-2019. No relationship was found between vaccines and GBS cases during vaccination roll-out in 2021. INTERPRETATION Incidence of GBS in Spain is similar to that of other countries. Despite prior reports describing a significant increase in COVID-19-associated GBS in Spain, we detected a significant drop of GBS incidence during the SARS-CoV-2 pandemic, probably due to prevention measures. No relationship was found between SARS-CoV-2 or vaccinations and GBS incidences at the population level but data on relationship of vaccinations and GBS at the individual level were not available. ### Competing Interest Statement LQ received research grants from Instituto de Salud Carlos III, Ministry of Economy and Innovation (Spain), CIBERER, Fundacio La Marato, GBS CIDP Foundation International, UCB and Grifols, received speaker or expert testimony honoraria from CSL Behring, Novartis, Sanofi-Genzyme, Merck, Annexon, Alnylam, Biogen, Janssen, Lundbeck, ArgenX, UCB, LFB, Octapharma and Roche, serves at Clinical Trial Steering Committee for Sanofi-Genzyme and Roche and is Principal Investigator for UCB CIDP01 trial. The other authors report no disclosures. ### Funding Statement This work is supported by Fondo de Investigaciones Sanitarias (FIS), Instituto de Salud Carlos III, Spain, under grant FIS PI22/00387. LM-A was supported by a personal Juan Rodes grant JR21/00060. MC-A was supported by a personal Rio Hortega grant CM21/00101. EP-G was supported by GBS/CIDP Foundation International under personal grant Benson Fellowship. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This project has been approved by the Institutional Ethics Comittee of the Hospital de la Santa Creu i Sant Pau (IIBSP-GSB-2023-151). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes * CI : confidence intervals COVID-19 : coronavirus disease 2019, GBS : Guillain-Barré syndrome HT : hypertension OTI : orotracheal intubation SARS-CoV-2 : severe acute respiratory syndrome coronavirus 2 SD : standard deviation, UTI : urinary tract infection.