title: Predictors of survival in children with methymalonic acidemia with homocystinuria in Beijing, China: a prospective cohort study.
abstract: OBJECTIVE
  (i) To determine whether clinical features and biochemical parameters help to predict survival of methylmalonic acidemia with homocystinuria; (ii) To find the cutoff values of biochemical parameters for predicting survival of methylmalonic acidemia with homocystinuria.
  
  
  METHODS
  A prospective cohort study.
  
  
  METHODS
  A pediatric tertiary hospital in Beijing; all patients were followed until death or June 2013.
  
  
  METHODS
  45 pediatric patients diagnosed with methylmalonic acidemia with homocystinuria between 2006 and 2012.
  
  
  METHODS
  The data of clinical characteristics and pretreatment biochemical parameters were collected. The Cox regression analysis was performed to identify independent risk factors for survival of patients with methylmalonic acidemia and homocystinuria. The best cutoff values for these independent factors were determined by the receiver characteristic curve.
  
  
  RESULTS
  Newborn onset (OR=6.856, 95%CI=2.241-20.976, P=0.001), high level of methylmalonic acid in urine (OR=1.022, 95%CI=1.011-1.033, P<0.001), and high level of urea in serum (OR=1.083, 95%CI=1.027-1.141, P=0.003) were independent negative risk factors for survival of patients with methylmalonic acidemia and homocystinuria. The cutoff values of maximum predictive accuracy of methylmalonic acid in urine and urea in serum were respectively 5.41 mmol/mmol creatinine and 7.80 mmol/L by receiver operating characteristic curve analysis.
  
  
  CONCLUSIONS
  The patients of methylmalonic acidemia with homocystinuria tend to have an adverse outcome if they have newborn onsets. Elevated urea and urinary methylmalonic acid are predictors of adverse outcomes for the patients. They show similar effect for predicting severe adverse prognosis. The combination of methylmalonic acid in urine concentration and urea in serum concentration provided the most accurate predictive tool.
authors.affiliation: Departments of Medical Laboratory, *Intensive Care Unit, #Neurology, ‡Nephrology and $Epidemiology and Biostatistics; Xuanwu Hospital, Beijing Children's Hospital, Capital Medical University, China. Correspondence to: Dr Wang Peichang, Department of Medical Laboratory, Xuanwu Hospital, Capital Medical University, Beijing, 100053, China. peichangwang@yahoo.com.
authors.forename: Li
authors.initials: L
authors.lastname: Qiliang
authors.forename: Song
authors.initials: S
authors.lastname: Wenqi
authors.forename: Wang
authors.initials: W
authors.lastname: Quan
authors.forename: Yang
authors.initials: Y
authors.lastname: Xinying
authors.forename: Li
authors.initials: L
authors.lastname: Jiuwei
authors.forename: Sun
authors.initials: S
authors.lastname: Qiang
authors.forename: Peng
authors.initials: P
authors.lastname: Xiaoxia
authors.forename: Wang
authors.initials: W
authors.lastname: Peichang
mesh_terms: D000592:Amino Acid Metabolism, Inborn Errors / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality*; D000068476:Beijing / Q000453:epidemiology; D005260:Female; D006712:Homocystinuria / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality*; D006801:Humans; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D016896:Treatment Outcome