Mastocytosis is a heterogeneous group of diseases characterized by abnormal proliferation of mast cells. Systemic mastocytosis (SM), in which abnormal mast cells are present in tissues beyond the skin, is divided into seven subcategories with varying degrees of severity and prognosis. Very little is known about the epidemiology of SM and its subcategories. This retrospective cohort study of 548 adults with SM diagnosed 1997–2010 was constructed using linked Danish national health registries. The most common subtype of mastocytosis was indolent SM (including urticaria pigmentosa) (n = 450; 82%), followed by SM with subtype unknown (n = 61; 11%), SM with associated clonal haematological non-mast cell lineage disease (n = 24; 4%), aggressive SM (n = 8; 2%), and mast cell leukaemia (n = 5; 1%). The incidence rate for SM (all subtypes including urticaria pigmentosa) was 089 per 100 000 per year. Cumulative incidence was 1246 per 100 000, and the 14-year limited-duration revalence as of 1 January, 2011 was 959 per 100 000. This nationwide cohort from Denmark is the first population-based epidemiological study of mastocytosis. In this cohort of patients aged 15 years and older, SM was found to be overall relatively rare with notable variation by subtype for patient characteristics, survival and epidemiological measures.
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EpidStat presented "Survival Synthesis: Methods for Meta-analysis of Survival Rates and Aggregation of Survival Data" at a poster session for the International Conference on Health Policy Statistics on January 10, 2018 in Charlston, SC. The poster details the methods used in Bylsma et al. Arteriovenous Fistulae for Haemodialysis: A Systematic Review and Metaanalysis of Efficacy and Safety Outcomes. European Journal of Vascular and Endovascular Surgery, 2017. We discussed the process of digitizing survival curves from the published literature and simulating individual patient data to derive survival statistics that were not published with the article. We conclude that while labor-intensive, the methodology makes the best use of available study data.