title: Prevalence and impact of initial misclassification of pediatric type 1 diabetes mellitus.
abstract: OBJECTIVE
  To characterize rates of initial misclassification of type 1 diabetes mellitus as type 2/unspecified diabetes mellitus in a cohort of children/adolescents and to examine the impact of misclassification on the risk of diabetes-related complications.
  
  
  METHODS
  An 11-year dataset (1996-2006) was analyzed. Inclusion criteria included age 17 years and younger, enrollees in South Carolina State Medicaid, and diagnosis of type 2/unspecified or type 1 diabetes mellitus for at least two visits, 15 days apart. Survival analysis was used to assess the association of "misclassification" with the incidence of diabetic ketoacidosis (DKA), and the cumulative incidence of neuropathy, nephropathy, and cardiovascular complications, after controlling for individual risk factors and comorbid conditions.
  
  
  RESULTS
  A total of 1130 individuals meeting the inclusion criteria were studied for a median of 7 years. Of the 1130 individuals, 669 (59.2%) maintained a diagnosis of type 2/unspecified diabetes mellitus, 205 (18.1%) were consistently diagnosed as type 1 diabetes mellitus, and the remaining 256 individuals (22.7%) were misclassified. Insulin treatment was used in 100% of the type 1 diabetes mellitus group and 73% of the misclassified group. Compared with the type 2 diabetes mellitus group, being misclassified was associated with earlier development of DKA (adjusted hazard ratio [aHR] 5.08, 95% confidence interval [CI] 3.09-8.37), neuropathy (aHR 1.94, CI 1.31-2.88), and nephropathy (aHR 1.72, CI 1.19-2.50), whereas being consistently classified with type 1 diabetes mellitus was associated only with earlier development of DKA (aHR 4.96, CI 2.56-9.61).
  
  
  CONCLUSIONS
  Proper categorization of pediatric diabetes can be challenging, especially with comorbid obesity. Failure to ascertain type 1 diabetes mellitus in a timely manner in a pediatric population may increase the risk of substandard care and diabetes-related complications.
authors.affiliation: Department of Epidemiology and Biostatistics, University of South Carolina Arnold School of Public Health, Columbia, SC 29203, USA.
authors.forename: Avnish
authors.initials: A
authors.lastname: Tripathi
authors.forename: Ali A
authors.initials: AA
authors.lastname: Rizvi
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Knight
authors.forename: Jeanette M
authors.initials: JM
authors.lastname: Jerrell
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D048909:Diabetes Complications / Q000453:epidemiology / Q000209:etiology; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis*; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis; D016883:Diabetic Ketoacidosis / Q000453:epidemiology / Q000209:etiology; D003928:Diabetic Nephropathies / Q000453:epidemiology / Q000209:etiology; D003929:Diabetic Neuropathies / Q000453:epidemiology / Q000209:etiology; D003951:Diagnostic Errors / Q000009:adverse effects / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D013022:South Carolina / Q000453:epidemiology