Changes in age composition and epidemiology of candidaemia, Iceland, 2012 to 2023

BACKGROUND Candidaemia places a substantial burden on healthcare systems. Long-term, population-based studies of candidaemia rates with appropriate adjustments for changes in age composition are lacking. AIM We aimed to determine trends in candidaemia incidence rates, species distribution, antifungal susceptibility, and concurrent antifungal use in Iceland between 2012 and 2023, as well as long-term (2000–2023) trends in age-standardised incidence rates (ASRs). METHODS We analysed patient data with blood cultures positive for Candida species, or yeasts previously assigned to the genus Candida. We calculated ASRs, standardised to the 2023 Icelandic population, and performed susceptibility testing on all available isolates. RESULTS Overall, we identified 207 candidaemia episodes in 193 patients. The average ASR was 5.2 cases per 100,000 population. The ASR increased significantly from 2012 to 2023 (incidence rate ratio (IRR) = 1.07; p = 0.001), mainly driven by increased rates among males (IRR = 1.10; p = 0.001). From 2000 to 2023, the ASR remained stable (average 5.8/100,000; IRR = 1.00). The ASR was higher among males, both during 2012–2023 (p = 0.014) and long-term (2000–2023, p = 0.001). Age-specific incidence rate was highest among > 80-year-old males (44.0/100,000). Candida albicans was the most frequent species (41.0%), followed by Nakaseomyces glabratus (27.2%) and Candida tropicalis (11.1%). Fluconazole susceptibility remained high (C. albicans 99%, C. tropicalis 75%, Candida parapsilosis 100%), and echinocandin resistance was rare (1.9%). CONCLUSION Despite an apparent increase from 2012 to 2023, candidaemia incidence in Iceland has remained stable in a long-term (24-year) perspective, when appropriate adjustments are made for the ageing population. Concurrently, the epidemiology has shifted towards non-albicans Candida infections.