Table 2.
Current CVs of each group categorized by control material vendors for HbA1c from 2012 to 2016 (%)a
| Manufacturer of control materials | Percentage of labs % (N/total) | Mass fraction | Current CVs | ||
|---|---|---|---|---|---|
| Median | IQRb | Median | IQRb | ||
| 2012 | |||||
| Bio‐Rad | 45.1 (138/306) | 5.70 | 0.32 | 2.12 | 1.93 |
| TOSOH | 10.9 (33/306) | 5.52 | 0.29 | 1.30 | 0.77 |
| Roche | 11.9 (36/306) | 6.20 | 0.88 | 4.10 | 2.86 |
| RANDOX | 5.5 (17/306) | 5.68 | 0.35 | 4.02 | 2.97 |
| In‐house preparation | 5.1 (16/306) | 6.10 | 0.67 | 2.16 | 1.91 |
| Others | 21.5 (66/306) | 5.52 | 0.67 | 3.00 | 3.17 |
| 2013 | |||||
| Bio‐Rad | 51.6 (158/306) | 5.61 | 0.21 | 2.00 | 1.09 |
| TOSOH | 12.0 (37/306) | 5.53 | 0.45 | 1.11 | 0.94 |
| Roche | 10.0 (31/306) | 6.10 | 0.60 | 3.27 | 2.19 |
| RANDOX | 4.8 (14/306) | 5.63 | 0.34 | 4.21 | 5.39 |
| In‐house preparation | 2.4 (7/306) | 5.90 | 0.89 | 1.44 | 1.25 |
| Others | 19.2 (58/306) | 5.43 | 0.56 | 2.71 | 3.06 |
| 2014 | |||||
| Bio‐Rad | 54.6 (167/306) | 5.34 | 0.22 | 2.01 | 1.36 |
| TOSOH | 14.9 (45/306) | 5.56 | 0.39 | 1.49 | 1.00 |
| Roche | 7.1 (22/306) | 6.30 | 0.84 | 3.32 | 2.37 |
| RANDOX | 4.3 (13/306) | 5.38 | 0.55 | 2.00 | 2.12 |
| In‐house preparation | 2.8 (9/306) | 5.80 | 1.23 | 2.39 | 2.58 |
| Others | 16.3 (50/306) | 5.37 | 0.45 | 1.79 | 1.58 |
| 2015 | |||||
| Bio‐Rad | 54.5 (166/306) | 5.33 | 0.21 | 1.98 | 1.46 |
| TOSOH | 15.1 (46/306) | 5.16 | 0.79 | 1.26 | 1.08 |
| Roche | 6.1 (19/306) | 5.70 | 0.45 | 2.59 | 1.97 |
| RANDOX | 3.6 (11/306) | 5.56 | 0.54 | 2.14 | 3.22 |
| In‐house preparation | 5.4 (16/306) | 5.67 | 1.09 | 1.82 | 1.41 |
| Others | 15.4 (47/306) | 5.39 | 0.32 | 1.64 | 2.66 |
| 2016 | |||||
| Bio‐Rad | 56.5 (173/306) | 5.39 | 0.23 | 1.76 | 1.51 |
| TOSOH | 15.2 (47/306) | 5.09 | 0.20 | 1.12 | 1.18 |
| Roche | 5.5 (17/306) | 5.79 | 0.36 | 2.54 | 1.23 |
| RANDOX | 4.2 (13/306) | 5.50 | 0.61 | 1.97 | 1.98 |
| In‐house preparation | 5.9 (18/306) | 5.72 | 1.15 | 1.52 | 1.27 |
| Others | 12.7 (39/306) | 5.40 | 0.41 | 1.25 | 1.69 |
a
The subgroup analyses of the current CVs and mass fraction were both for level 1.
b
Interquartile range (IQR) is equal to the difference between the upper and lower quartiles, IQR=Q3‐Q1.