Incidence, prevalence and mortality of anorexia nervosa in individuals with childhood-onset type 1 diabetes: a nationwide retrospective cohort study in Sweden

OBJECTIVES: To investigate the incidence, prevalence and mortality of anorexia nervosa (AN) among individuals with childhood-onset type 1 diabetes (T1D) compared with matched controls in Sweden. DESIGN: Retrospective nationwide cohort study using linked registry data. SETTING: Nationwide, Sweden; population-based registers (covering the period 1977-2019). PARTICIPANTS: 12 202 individuals diagnosed with T1D before age 15 years (5618 females; 6584 males) and 48 484 age-matched, sex-matched and municipality-matched controls without diabetes (23 618 females; 24 866 males). PRIMARY AND SECONDARY OUTCOME MEASURES: AN diagnoses (International Classification of Diseases-10 codes F50.0 and F50.1) identified via the National Patient Register. Outcomes were period prevalence, point prevalence at ages 15 and 20 years, 10-year incidence rates and proportional mortality ratios (PMR), stratified by sex. ORs and incidence rate ratios (IRR) with 95% CIs were estimated using Mantel-Haenszel methods; Kaplan-Meier analysis compared time to AN diagnosis between groups. RESULTS: The period prevalence of AN among females with T1D was 1.9% compared with 1.1% in controls (OR 1.64, 95% CI 1.31 to 2.06; p