Analysis of causes and outcomes of principal secondary thrombotic microangiopathy: a 9-year cohort study from a tertiary pediatric center in China

Background Few large-scale cohort studies have reviewed consecutive cases of thrombotic microangiopathy (TMA), especially in children. Methods The aim of our study was to evaluate causes and outcomes of TMA at a tertiary pediatric center in China over a 9-year period. Results We retrospectively analyzed 303 consecutive pediatric patients with a first-episode TMA. Secondary TMA was the most common type (n = 172; 57%), followed by atypical hemolytic uremic syndrome (aHUS: n=93; 31%), thrombotic thrombocytopenic purpura (TTP: n=24; 8%), and Shiga toxin–associated HUS (STEC-HUS: n=14; 5%). Among the 172 cases of secondary TMA, the most common causes were hematopoietic stem cell transplantation (n = 95; 55%) and systemic diseases (n = 40; 23%). After a 35-month median follow-up, death or kidney failure occurred in 53 (31%), 7 (8%), 1 (4%), and 0 patients with secondary TMA, aHUS, TTP, and STEC-HUS, respectively. Multivariate Cox regression analysis showed that secondary TMA (HR = 3.57; 95% CI, 1.53–8.30; P < 0.01), the presence of heart failure and/or shock at onset (HR = 2.21; 95% CI, 1.24–3.93; P=0.01), and the need for mechanical ventilation support due to respiratory failure (HR = 3.88; 95% CI, 2.19–6.88; P < 0.001) were the independent risk factors for death or kidney failure. Conclusion This study shows that secondary TMA is the predominant form of pediatric TMA. Secondary TMA, heart failure/shock, and the requirement for mechanical ventilation were identified as independent risk factors for death or kidney failure in children.