Seasonal patterns of acute laryngitis in preschool children: a single-center retrospective registry study

Abstract Background Acute laryngitis is a common cause of upper airway symptoms and healthcare use in preschool children. Its occurrence varies during the year, but the timing and magnitude of this pattern have not been well described in routine pediatric care. We assessed seasonal and longer-term temporal patterns in daily acute laryngitis episodes. Methods This retrospective, single-center registry study included 3,430 acute laryngitis episodes recorded at a paediatric hospital in Olsztyn, Poland, between 1 October 2017 and 8 August 2025 (2,869 days). Daily counts were analysed using negative binomial regression adjusted for day of the week and calendar time. Annual seasonality was modelled using annual and semi-annual harmonic terms. Alternative Poisson and zero-inflated negative binomial models together with an analysis excluding the main COVID-19 disruption period were used as sensitivity analyses. Results The mean daily number of episodes was 1.196, and 44.4% of days had no recorded episodes. Compared with summer, the adjusted daily episode rate was higher in autumn (IRR 1.94, 95% CI 1.55–2.42) and winter (IRR 1.64, 95% CI 1.32–2.03). October had the highest monthly mean; in the categorical model its rate was 2.65 times the August rate (95% CI 1.97–3.58). The adjusted harmonic model estimated the seasonal peak on 7 November (95% CI 24 October-27 November). The broad seasonal pattern was present in both girls and boys and did not differ significantly by sex. The more detailed monthly pattern differed between the sexes ( p = 0.027). Conclusions Acute laryngitis in preschool children showed a clear seasonal pattern, with the highest observed monthly burden in October and an adjusted seasonal peak in early November. The result was robust to alternative count models and exclusion of the main COVID-19 disruption period. These findings may support planning of paediatric healthcare services during periods of increased demand.