Assessment of quality control system by sigma metrics and quality goal index ratio: A roadmap towards preparation for NABL

Table 4 Sigma metrics (Level 1 and 2) and quality goal index ratio (Level 1 and 2) of 16 parameters calculated from coefficient of variation (Level 1 and 2), total allowable error (Clinical Laboratory Improvement Act), and bias %, for a period of one year (Jan-Dec, 2017)

Parameter	CV %		Bias %	TEa (CLIA)	TE (calculated)		Sigma
	Level 2	Level 3			Level 2	Level 3	Level 2	Level 3
Glucose	2.74	2.04	3.66	10	8.18	7.03	2.31	3.11
Urea	4.21	3.4	-2.94	9	4.01	2.67	2.84	3.51
Creatinine	5.42	3.22	-8.01	15	0.93	-2.7	4.25	7.15
Total bilirubin	3.66	2.78	-1.4	20	4.64	3.19	5.85	7.7
Total protein	3	3.06	-6.7	10	-1.75	-1.65	5.57	5.46
Albumin	2.12	2	-8.32	10	-4.82	-5.02	8.64	9.16
Calcium	2.54	2.36	3.23	11	7.42	7.12	3.06	3.29
Phosphorus	4.91	3.27	-14	10	-5.9	-8.6	4.89	7.34
Uric acid	3.22	2.61	-12.2	17	-6.89	-7.89	9.07	11.19
Total cholesterol	2.86	2.66	5.08	10	9.8	9.47	1.72	1.85
Triglyceride	4.74	3.01	7.41	25	15.23	12.38	3.71	5.84
HDL cholesterol	3.69	3.62	-17.4	30	-11.31	-11.43	12.85	13.09
AST	4.77	3.11	13.2	20	21.07	18.33	1.43	2.19
ALT	4.75	3.23	12.7	20	20.54	18.03	1.54	2.26
ALP	3.27	2.75	-2.56	30	2.84	1.98	9.96	11.84
Amylase	4.19	3.32	9.67	30	16.58	15.15	4.85	6.12

CV: Coefficient of variation; TE: Total error; CLIA: Clinical Laboratory Improvement Act; HDL: High-density lipoprotein; AST: Aspartate transaminase; ALT: Alanine transaminase; ALP: Alkaline phosphatase.