BSPED2009 Oral Communications Oral Communications 3 (8 abstracts)
1Royal Manchester Childrens Hospital, Manchester, UK; 2University of Manchester, Manchester, UK.
Introduction: Factors determining remission and relapse in children with thyrotoxicosis include ethnicity, age and thyroid hormone levels at diagnosis. We investigated if similar factors influence remission and relapse in a contemporary cohort of children with autoimmune thyrotoxicosis treated by dose titration of carbimazole.
Methods: Forty-seven children (39 females) with thyrotoxicosis, treated with carbimazole, were followed up for ≥2 years. Initial remission was defined as first cessation of carbimazole and long term remission was defined if remission lasted >2 years. Relapse was defined as recommencement of carbimazole following remission or a dose increment on existing treatment.
Results: First remission was achieved in 28 (60%) children after a median (range) of 1.5 (0.3, 3.1) years after diagnosis, while long-term remission was achieved in 8 (17%). Relapse occurred in 37 (78%) children 1.9 (0.2, 6.7) years after diagnosis. Following remission, relapse occurred in 20 (71%) children, while remission after relapse was rare at 14%. Treatment with surgery or radiotherapy was given to 22 (46%) children. In survival analysis, risk of relapse was associated with a lower body mass index at diagnosis (hazard ratio (HR) (95% confidence interval) 14.5 (1.6, 126.2), P=0.02) and a higher dose of carbimazole 6 months after diagnosis (HR 1.17 (1.0, 1.3), P=0.03) but not with non-Caucasian ethnicity, younger age or high serum free thyroxine levels. In linear regression (R2=0.68, P=0.02), time between initial remission and relapse was negatively correlated with time to achieve initial remission (P=0.002) and initial dose of carbimazole (P=0.01), when controlling for ethnicity, age, sex and weight, suggesting an association of greater disease severity with a higher risk of relapse.
Conclusion: Most children with thyrotoxicosis treated with dose titration of carbimazole relapse after remission, especially if they are thin at diagnosis and remain on high treatment doses at 6 months after diagnosis.