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

Table 1 The CV % of 16 parameters of level 2 internal quality control for a period of one year (Jan-Dec, 2017) and their average

Parameter	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Average
Glucose	2.04	1.81	2.12	1.98	2.99	2.07	4.74	2.96	3.07	4.01	2.94	2.17	2.74
Urea	3.13	4.27	3.87	5.84	4.08	5.30	4.43	4.08	3.89	3.70	3.61	4.39	4.21
Creatinine	7.02	8.30	8.02	7.15	4.47	3.38	6.28	4.13	3.45	4.02	4.26	4.66	5.42
Total bilirubin	2.88	3.89	3.27	2.93	2.52	4.60	4.75	4.62	2.99	2.54	4.07	4.86	3.66
Total protein	1.95	2.18	2.67	2.94	3.81	2.99	3.03	3.00	3.83	3.99	2.34	3.27	3.00
Albumin	0.99	2.55	2.04	0.96	3.40	2.18	1.86	1.86	2.27	1.94	3.00	2.47	2.12
Calcium	2.09	2.90	2.76	2.70	2.75	2.38	2.57	2.55	2.06	3.24	2.74	1.85	2.54
Phosphorus	5.48	6.83	6.70	4.47	5.40	6.72	4.52	3.58	3.87	3.68	4.22	3.54	4.91
Uric acid	3.63	4.17	2.73	3.59	3.64	3.81	2.80	3.21	3.36	2.53	2.66	2.6	3.22
Total cholesterol	2.26	1.86	3.42	2.17	2.53	4.16	3.64	2.62	2.38	2.87	3.00	3.49	2.86
Triglyceride	3.74	4.95	5.07	5.30	7.17	5.07	5.36	3.96	3.62	4.23	5.13	3.29	4.74
HDL cholesterol	5.08	3.43	5.68	1.74	4.56	2.85	4.57	3.89	3.14	2.90	2.94	3.56	3.69
AST	5.74	6.18	6.79	4.22	4.59	4.97	5.72	4.31	3.49	3.40	4.38	3.56	4.77
ALT	5.82	6.10	4.80	5.09	5.25	5.39	5.56	5.64	1.99	3.05	4.90	3.46	4.75
ALP	2.98	3.59	2.81	2.56	2.51	2.87	3.02	3.77	2.26	5.97	4.17	2.84	3.27
Amylase	4.03	5.70	4.71	4.24	4.00	3.14	5.47	4.72	4.10	3.30	3.07	3.87	4.19

CV: Coefficient of variation; IQC: Internal quality control; HDL: High-density lipoprotein; AST: Aspartate transaminase; ALT: Alanine transaminase; ALP: Alkaline phosphatase.

Table 2 The CV % of 16 parameters of level 3 internal quality control for a period of one year (Jan-Dec, 2017) and their average

Parameter	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Average
Glucose	1.20	1.31	1.59	1.50	1.96	1.65	2.80	2.05	4.32	2.45	1.76	1.90	2.04
Urea	2.60	2.91	3.50	4.40	3.23	3.84	3.41	3.36	3.65	4.02	3.28	2.60	3.40
Creatinine	3.34	3.49	5.29	4.77	2.75	1.97	3.10	3.03	2.98	2.95	2.92	2.16	3.22
Total bilirubin	2.50	2.35	2.52	2.05	2.35	3.34	2.86	3.99	2.12	3.91	2.66	2.71	2.78
Total protein	2.36	2.41	1.96	2.36	3.84	2.90	2.75	4.24	3.50	3.82	3.25	3.34	3.06
Albumin	2.25	1.95	3.29	1.73	1.69	1.84	1.99	1.69	1.86	1.74	1.96	2.02	2.00
Calcium	1.37	2.95	2.57	2.54	2.00	2.21	2.92	2.93	2.14	2.22	2.34	2.2	2.36
Phosphorus	3.50	4.85	4.77	4.78	3.85	4.02	2.22	1.88	1.62	2.78	2.41	2.61	3.27
Uric acid	2.90	3.03	2.33	2.12	2.66	2.42	3.56	2.51	2.54	1.97	3.11	2.23	2.61
Total cholesterol	2.09	1.30	2.86	2.35	2.61	4.61	2.30	3.91	2.03	2.57	2.6	2.79	2.66
Triglyceride	2.50	2.26	3.61	2.85	3.18	4.22	3.80	2.70	1.98	2.72	3.49	2.83	3.01
HDL cholesterol	3.03	3.72	4.19	1.95	5.17	4.54	5.22	2.91	1.97	4.35	4.1	2.35	3.62
AST	2.12	3.40	2.65	2.75	3.45	2.55	3.48	3.76	3.95	2.92	3.62	2.70	3.11
ALT	3.19	2.81	3.09	2.89	4.45	2.66	4.22	4.32	2.89	2.67	2.56	3.11	3.23
ALP	2.93	2.61	2.67	2.74	2.59	2.53	2.53	2.3	2.30	4.08	2.82	2.90	2.75
Amylase	3.10	3.51	3.57	3.47	3.30	2.84	5.30	2.25	3.03	3.42	2.73	3.33	3.32

CV: Coefficient of variation; IQC: Internal quality control; HDL: High density lipoprotein; AST: Aspartate transaminase; ALT: Alanine transaminase; ALP: Alkaline phosphatase.

Table 3 The bias % obtained from external quality assurance scheme from CMC Vellore for 16 parameters for a period of one year (Jan-Dec, 2017) and their average

Parameter	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Average
Glucose	10.8	-9.7	6.1	1.2	1.2	6	3.8	3.2	0.9	7.5	8.5	4.5	3.66
Urea	-3.8	-7.2	-2.5	-2.2	2.2	-12.2	-1.8	-5.4	4	-10.1	-1.6	5.3	-2.94
Creatinine	-8.3	-13.6	-18.8	-7.7	-10.9	-9.1	-9.9	14.3	-7.5	-14	0	-10.7	-8.01
Total bilirubin	0	-20	-4.8	5.4	5.9	-5.9	-4	-10	3.3	-3.8	6.2	10.9	-1.4
Total protein	-4.2	-14	-2	-6	-2	-9.6	-5.8	-8.3	-6.2	-10	-8.2	-4.1	-6.7
Albumin	-3.3	-16.1	-6.5	-9.4	-12.9	-15.6	-6.3	-10	-10	-6.5	0	-3.3	-8.32
Calcium	1.2	-0.8	4.1	-4.3	3.1	-1.6	2.2	3.4	1.1	2.1	15.7	12.6	3.23
Phosphorus	-12.8	-37.5	-20.6	-15.8	-12.5	-9.3	-25.9	-4.4	-20	1.9	-18.8	7.3	-14
Uric acid	-14.5	-20.4	-16.2	-11.6	-22.9	-3.3	-4.8	-26.7	-5.7	-7.1	-8.3	-5.5	-12.2
Total cholesterol	-0.6	-6.4	1.8	2	-1.9	-3.5	3.3	6	26.9	8.9	15.8	8.7	5.08
Triglyceride	9.1	-1.3	4	5.9	-2.8	6.5	12.2	1.5	15.5	17.5	11.5	9.4	7.41
HDL cholesterol	-12.1	-23.6	-19.4	-14.7	-18	-27.7	-13	-15	-17.4	-18	-15.3	-14.6	-17.4
AST	20	2.4	20.7	7.6	0.8	5.8	13.7	17.8	20.1	11	14.8	24.3	13.2
ALT	33.5	12.3	22	-3.6	6.7	-4.3	13.2	-11.9	18.3	7.6	29	29.6	12.7
ALP	-5.6	-5	4.3	-8.3	-6	-18.2	-6.1	-4.5	1.5	6.6	7.3	3.2	-2.56
Amylase	12.4	-0.7	17.9	4.8	8.2	4.8	15.1	15.3	17.6	5.9	-1.6	16.4	9.67

CV: Coefficient of variation; EQAS: External quality assurance scheme; HDL: High-density lipoprotein; AST: Aspartate transaminase; ALT: Alanine transaminase; ALP: Alkaline phosphatase.

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.

Table 5 Sigma metrics of various parameters

Sigma metrics	Level 2	Level 3
< 3	Glucose, urea, total cholesterol, AST, ALT	Total cholesterol, AST, ALT
3-6	Creatinine, total bilirubin, total protein, calcium, phosphorus, triglyceride	Glucose, urea, total protein, calcium, triglyceride
> 6	Albumin, uric acid, HDL-cholesterol, ALP	Creatinine, total bilirubin, albumin, uric acid, HDL-cholesterol, ALP, amylase

HDL: High-density lipoprotein; AST: Aspartate transaminase; ALT: Alanine transaminase; ALP: Alkaline phosphatase.

Table 6 Quality goal index ratio of analytes performed low for sigma for accuracy and precision problem

Analytes	Qc levels	Bias%	CV%	Sigma	QGI	Problem
Glucose	Level 2	3.66	2.74	2.31	0.89	Imprecision and inaccuracy
Urea	Level 2	-2.94	4.21	2.84	0.47	Imprecision
TC	Level 2	5.08	2.86	1.72	1.18	Inaccuracy
	Level 3	5.08	2.66	1.85	1.27	Inaccuracy
AST	Level 2	13.2	4.77	1.43	1.84	Inaccuracy
	Level 3	13.2	3.11	2.19	2.83	Inaccuracy
ALT	Level 2	12.7	4.75	1.54	1.78	Inaccuracy
	Level 3	12.7	3.23	2.26	2.62	Inaccuracy

QGI: Quality goal index ratio; AST: Aspartate transaminase; ALT: Alanine transaminase; TC: Total cholesterol.