Table. 1. Table 1

Bias based on KEQAS ABCr PT survey data from 2011 to 2019

Trial	Total N of participating labs	N of response results^*	N of outliers^†	Bias (%)		Bias (mg/dL)

				Mean (95% CI)	SD	Mean (95% CI)	SD
2011-A	54	161	1	10.82 (9.45–12.19)	12.15	0.096 (0.080–0.112)	0.102
2011-B	56	166	0	7.12 (5.77–8.46)	11.02	0.075 (0.058–0.091)	0.108
2012-A	103	303	2	9.33 (8.33–10.33)	10.79	0.082 (0.072–0.092)	0.090
2012-B	108	323	0	6.18 (5.22–7.15)	9.86	0.062 (0.050–0.073)	0.105
2013-A	140	420	1	5.78 (4.93–6.62)	10.10	0.049 (0.036–0.061)	0.133
2013-B	139	416	0	7.63 (6.78–8.48)	10.81	0.066 (0.057–0.074)	0.091
2014-A	176	527	4	4.04 (3.29–4.80)	11.29	0.024 (0.013–0.036)	0.132
2014-B	167	501	2	–0.01 (–0.79–0.76)	7.07	–0.004 (–0.012–0.004)	0.091
2015-A	175	525	1	1.36 (0.60–2.11)	6.67	0.018 (0.011–0.026)	0.090
2015-B	178	534	1	3.64 (2.89–4.39)	7.97	0.036 (0.028–0.045)	0.100
2016-A	146	437	3	2.37 (1.54–3.20)	7.69	0.02 (0.011–0.029)	0.098
2016-B	150	450	2	4.01 (3.20–4.83)	10.04	0.027 (0.019–0.036)	0.091
2017-A	153	459	3	1.77 (0.96–2.58)	8.82	0.008 (0.000–0.015)	0.080
2017-B	167	501	3	2.05 (1.27–2.82)	8.95	0.014 (0.008–0.02)	0.068
2018-A	197	591	1	2.36 (1.65–3.07)	8.57	0.008 (0.000–0.015)	0.093
2018-B	200	600	0	3.87 (3.17–4.58)	8.11	0.033 (0.027–0.039)	0.074
2019-A	227	681	2	0.45 (–0.21–1.11)	6.40	–0.003 (–0.009–0.003)	0.077
2019-B	227	681	2	0.20 (–0.47–0.86)	7.36	–0.018 (–0.026––0.009)	0.111

^*N=3 samples per trial; ^†An outlier was defined as a result with an absolute percentage bias >50% of the target Cr concentration.

Abbreviations: ABCr PT, accuracy-based creatinine proficiency testing; Cr, creatinine; KEQAS, Korean Association of External Quality Assessment Service.

Ann Lab Med 2021;41:372~379 https://doi.org/10.3343/alm.2021.41.4.372