title: Linear association between household income and metabolic control in children with insulin-dependent diabetes mellitus despite free access to health care.
abstract: BACKGROUND
  In health care systems with a user fee, the impact of socioeconomic factors on pediatric insulin-dependent diabetes mellitus (IDDM) control could be due to the cost of accessing care.
  
  
  OBJECTIVE
  There is a linear association between household income and the average glycosylated hemoglobin (HbA1c) of children and adolescents with IDDM despite free access to health care.
  
  
  METHODS
  We used a linear regression model to examine the association between normalized average HbA1c of 1766 diabetic children (diagnosed at our institution from 1980 to 2011 before 17 years of age) and the median household income of their neighborhoods (obtained from Statistics Canada, 2006 Census data).
  
  
  RESULTS
  We found a negative linear association (P < .001; r = -0.2) between the level of income and metabolic control assessed by HbA1c after controlling for sex, age at diagnosis, duration of diabetes, ethnicity, geographical factors, frequency of visits, current age (as a proxy for change in practice over time), and change of measurement methods of HbA1c across time. For every increase of $15,000 in annual income, HbA1c decreased by 0.1%.
  
  
  CONCLUSIONS
  We report a linear association of household income with metabolic control of IDDM in childhood. Given that Canada has a system of free universal access to health care, confounding by access to care is unlikely. Considering the impact of poorly controlled IDDM in childhood on the development of long-term complications, our findings suggest that the higher complication rate found in adults of low socioeconomic status might originate from the poor control that they experienced in childhood. Support for the care of IDDM children from low-income neighborhoods should be increased.
authors.affiliation: Endocrinology and Diabetes Service, Centre Hospitalier Universitaire Sainte-Justine, Department of Pediatrics, University of Montréal, Montréal, Canada H3T 1C5. johnny.deladoey@umontreal.ca
authors.forename: Johnny
authors.initials: J
authors.lastname: Deladoëy
authors.forename: Mélanie
authors.initials: M
authors.lastname: Henderson
authors.forename: Louis
authors.initials: L
authors.lastname: Geoffroy
mesh_terms: D000293:Adolescent; D002170:Canada; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D048909:Diabetes Complications / Q000191:economics / Q000517:prevention & control; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy* / Q000191:economics*; D005191:Family Characteristics; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis; D006297:Health Services Accessibility / Q000191:economics; D006801:Humans; D006943:Hyperglycemia / Q000517:prevention & control*; D007003:Hypoglycemia / Q000517:prevention & control*; D007004:Hypoglycemic Agents / Q000191:economics / Q000627:therapeutic use*; D007328:Insulin / Q000191:economics / Q000627:therapeutic use*; D008297:Male; D012111:Residence Characteristics; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D013222:State Medicine
chemical_list: D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; D007328:Insulin; C517652:hemoglobin A1c protein, human