Seasonality in the incidence of anti‐GQ1b antibody syndrome—A territory‐wide study

AIMS: To investigate any seasonality in the incidence of anti‐GQ1b antibody syndrome (AGS). METHODS: We conducted a retrospective observational study in all hospitalized patients in local public hospitals from January 2013 to December 2018. AGS was defined by hospitalized patients with positive serum anti‐GQ1b IgG, presumably encompassing Miller‐Fisher syndrome, Bickerstaff brainstem encephalitis and Guillain–Barré syndrome (GBS) variants. GBS cases were retrieved from the computerized database by diagnostic label. Campylobacter jejuni infection (CJI) injection was identified by positive stool culture. Monthly incidence rates of AGS, GBS and CJI were calculated. Poisson and negative binomial regression models with long‐term time trend were fitted to characterize the seasonal pattern. RESULTS: A total of 237, 572 and 2434 cases of AGS, GBS and CJI were identified, respectively, in a population of 7.3 million. The annual incidence rate of AGS was 0.54 per 100,000 person‐years. AGS was demonstrated to have an annual peak in the spring season, from March to April, which was congruent with that of GBS and slightly lagged the annual peak of CJI from February to March (likelihood ratio tests all p < .001 for the seasonal terms). CONCLUSION: The incidence of AGS peaks in springtime, which is congruent with that of GBS and lags around one month after that of CJI. We demonstrated that AGS has a clear seasonality in occurrence.