Whooping cough hospitalisations among patients with chronic conditions: a retrospective analysis of incidence and costs, France, 2008 to 2020.

BACKGROUNDIn European countries, including France, the incidence and costs of whooping cough in people with chronic conditions remains understudied.AIMWe aimed to estimate cumulative incidence and costs of whooping cough hospitalisations in children, adolescents and adults with chronic conditions in France.METHODSWe extracted data from patients hospitalised with whooping cough with or without underlying chronic conditions, asthma, chronic obstructive pulmonary disease (COPD), diabetes and immunocompromising conditions between 2008 and 2020 using the Système National des Données de Santé (SNDS).RESULTSAmong the 10,893 patients hospitalised with whooping cough in 2008-2020, asthma and/or COPD were the most common chronic conditions. Of the 7,212 children and adolescents hospitalised, 1,263 (17.5%) had asthma and 68 (0.9%) had an immunocompromising condition. Of the 3,681 adults, 2,297 (62.4%) had asthma and/or COPD, 594 (16.1%) had an immunocompromising condition and 454 (12.3%) had diabetes. In children and adolescents, the highest cumulative incidence ratio (CIR) was among patients with an immunocompromising condition (adjusted CIR = 3.6; 95% confidence interval (CI): 2.8-4.6) whereas in adults, patients with asthma and/or COPD had the highest adjusted CIR (18.6; 95% CI: 17.4-19.9). Median hospitalisation costs were the highest for patients with an immunocompromising condition (EUR 4,401). No significant changes in healthcare resource utilisation were observed before and after whooping cough hospitalisation in adults.CONCLUSIONChronic conditions are associated with higher cumulative incidence of whooping cough-related hospitalisation in France. This highlights the importance of reducing whooping cough circulation, through strengthening vaccination programmes, particularly for those with chronic conditions.