title: Clinical outcome indicators, disease prevalence and test request variability in primary care.
abstract: OBJECTIVE
  To describe differences in biochemistry test request rates (adjusted for practice size) between general practices and to investigate whether differences in HbA(1c) and thyroid function test request rates are related either to the practice prevalence of hypothyroidism and diabetes or to Quality and Outcome Framework (QOF) scores.
  
  
  METHODS
  Information on test request rates, prevalence of diabetes and hypothyroidism, and QOF data over a one-year period were obtained from 58 practices covering a population of 284,609 patients. Spearman's rank correlation tests were used to investigate relationships between adjusted test request rates.
  
  
  RESULTS
  There was wide variability in adjusted test request rates (lowest for HbA(1c) and highest for immunoglobulins). The ranking of practices for different tests was highly correlated. There was no relationship between adjusted test request rates for HbA(1c) and thyroid function and the reported prevalence of diabetes and hypothyroidism, respectively, nor was there any relationship with QOF scores in diabetes and hypothyroidism.
  
  
  CONCLUSIONS
  There is wide variability in test request rates in general practice that do not appear to be related to disease prevalence or crude clinical outcome measures.
authors.affiliation: Clinical Chemistry Laboratory, Altnagelvin Hospital, Western Health and Social Care Trust, Londonderry, N. Ireland. Maurice.Okane@westerntrust.hscni.net
authors.forename: Maurice J
authors.initials: MJ
authors.lastname: O'Kane
authors.forename: Lee
authors.initials: L
authors.lastname: Casey
authors.forename: P L Mark
authors.initials: PL
authors.lastname: Lynch
authors.forename: Noel
authors.initials: N
authors.lastname: McGowan
authors.forename: John
authors.initials: J
authors.lastname: Corey
mesh_terms: D019963:Clinical Chemistry Tests / Q000706:statistics & numerical data*; D003920:Diabetes Mellitus / Q000453:epidemiology* / Q000378:metabolism; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology* / Q000378:metabolism; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data*; D011320:Primary Health Care / Q000706:statistics & numerical data*; D011786:Quality Control