title: Application of sigma metrics for the assessment of quality control in clinical chemistry laboratory in Ghana: A pilot study.
abstract: BACKGROUND
  Sigma metrics provide a uniquely defined scale with which we can assess the performance of a laboratory. The objective of this study was to assess the internal quality control (QC) in the clinical chemistry laboratory of the University of Cape Cost Hospital (UCC) using the six sigma metrics application.
  
  
  METHODS
  We used commercial control serum [normal (L1) and pathological (L2)] for validation of quality control. Metabolites (glucose, urea, and creatinine), lipids [triglycerides (TG), total cholesterol, high-density lipoprotein cholesterol (HDL-C)], enzymes [alkaline phosphatase (ALP), alanine aminotransferase (AST)], electrolytes (sodium, potassium, chloride) and total protein were assessed. Between-day imprecision (CVs), inaccuracy (Bias) and sigma values were calculated for each control level.
  
  
  RESULTS
  Apart from sodium (2.40%, 3.83%), chloride (2.52% and 2.51%) for both L1 and L2 respectively, and glucose (4.82%), cholesterol (4.86%) for L2, CVs for all other parameters (both L1 and L2) were >5%. Four parameters (HDL-C, urea, creatinine and potassium) achieved sigma levels >1 for both controls. Chloride and sodium achieved sigma levels >1 for L1 but <1 for L2. In contrast, cholesterol, total protein and AST achieved sigma levels <1 for L1 but >1 for L2. Glucose and ALP achieved a sigma level >1 for both control levels whereas TG achieved a sigma level >2 for both control levels.
  
  
  CONCLUSIONS
  Unsatisfactory sigma levels (<3) where achieved for all parameters using both control levels, this shows instability and low consistency of results. There is the need for detailed assessment of the analytical procedures and the strengthening of the laboratory control systems in order to achieve effective six sigma levels for the laboratory.
authors: Department of Laboratory Technology, University of Cape Coast, Kumasi, Ghana.
authors: Justice
authors: J
authors: Afrifa
authors: Department of Laboratory Technology, University of Cape Coast, Kumasi, Ghana.
authors: Seth A
authors: SA
authors: Gyekye
authors: Department of Molecular Medicine, School of Medical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
authors: William K B A
authors: WK
authors: Owiredu
authors: Department of Laboratory Technology, University of Cape Coast, Kumasi, Ghana.
authors: Richard K D
authors: RK
authors: Ephraim
authors: Department of Laboratory Technology, University of Cape Coast, Kumasi, Ghana.
authors: Samuel
authors: S
authors: Essien-Baidoo
authors: Department of Laboratory, University of Cape Coast Hospital, Cape Coast, Ghana.
authors: Samuel
authors: S
authors: Amoah
authors: Department of Laboratory Technology, University of Cape Coast, Kumasi, Ghana.
authors: David L
authors: DL
authors: Simpong
authors: Department of Laboratory, University of Cape Coast Hospital, Cape Coast, Ghana.
authors: Aaron R
authors: AR
authors: Arthur
keywords: Imprecision; inaccuracy; quality control; six sigma
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