Incidence and impact of prior history of serious infection in paediatric lymphoma: A population‐based study

Children, adolescents and young adults (CAYA) with lymphoma may have undiagnosed inborn errors of immunity (IEI). We assessed the prevalence of prior severe infections in CAYA lymphoma and evaluated its association with post-lymphoma outcomes through a population-based cohort of Ontario CAYA aged 0-21 years diagnosed with Hodgkin or non-Hodgkin lymphoma from 1992 to 2022, matching each case to five controls. Population-based healthcare data identified pre-diagnosis infection-related encounters. We also compared post-diagnosis intensive care unit (ICU) admissions and mortality in lymphoma patients with and without pre-lymphoma infection-related ICU admissions. 2950 CAYA (mean age diagnosis 15.5 ± 4.8 years) and 14 750 matched controls were included. Infection-related ICU admissions were nearly nine times more common among cases versus controls [4.8% vs. 0.6%; odds ratio [OR] 8.9 (95% confidence interval [95% CI]: 6.7-11.7); p < 0.0001]. CAYA with lymphoma and pre-lymphoma infection-related ICU admissions had significantly higher risks of post-lymphoma ICU admissions (6-month incidence: 38.5% vs. 6.6%; hazard ratio [HR] 7.3 [95% CI: 5.7-9.3]; p < 0.0001) and mortality (5-year overall survival: 66.6% vs. 93.5%; HR 6.6 [95% CI: 5.0-8.6]; p < 0.0001) than those without such a history. Findings did not differ by lymphoma subtype or age at diagnosis. A significant subset of CAYA with lymphoma likely has an undiagnosed IEI, with higher post-lymphoma infection and mortality risks. Systematic IEI evaluations may be warranted.