Serious complications due to acute rhinosinusitis in children up to five years old in Stockholm, Sweden - Still a challenge in the pneumococcal conjugate vaccine era.

OBJECTIVES: The aim of this study was to analyze the rate of admissions, the rate of serious complications (postseptal orbital complications and surgery) and the bacterial etiology of acute rhinosinusitis in hospitalized children under five years old in Stockholm County, eight years after the introduction of the pneumococcal conjugate vaccine (PCV). The secondary aim was to compare this period with the period four years prior to the vaccine's introduction. METHODS: This was a population-based, descriptive observational study with retrospectively collected data from 1 July 2008 to 30 June 2016 in Stockholm County. Hospital admissions of children with a discharge diagnosis of rhinosinusitis and related complications were reviewed and compared to the pre-PCV period of 2003-2007. RESULTS: A total of 215 children were admitted, for a yearly incidence of 18.8 per 100 000 children (22.8 for boys, 14.6 for girls). Computer tomography-verified postseptal orbital complications occurred in 29 cases (13.5%) and surgery was necessary in nine (4.2%). Pathogens other than Streptococcus pneumoniae were found in the cases with postseptal complication or surgery (Streptococcus pyogenes in four, Haemophilus influenzae in three and Staphylococcus aureus in one case). In comparison to the four years pre-PCV, the incidence of admission decreased from 43.81 to 20.31 and 17.45 per 100 000/year for the two four-year periods after vaccine introduction. The incidence of CT-verified postseptal complication increased slightly from 1.51 to 2.34 and 2.74 per 100 000/year. The incidence of surgeries increased marginally but continued to be very low, from 0.22 to 0.54 and 1.03 per 100 000/year. CONCLUSIONS: Complications due to acute rhinosinusitis in children living in Stockholm County continues to be very rare after the introduction of pneumococcal vaccine. Hospitalization has decreased for children under five years old after PCV introduction, but the incidence or postseptal complications and surgery in the same population increased slightly. Predominantly bacteria other than Streptococcus pneumoniae was found. There is a need of larger studies to determine trends, and a need of prospective studies to elucidate the bacterial etiology, of serious complications due to acute rhinosinusitis in children.