Table 4

Summary of modified Bland-Altman comparison

BGM systemValid trialsBias (%)Coefficient of variation (%)*95% limits of agreementLarger absolute limit boundary (%)
Lower limitUpper limit
Contour Next312−1.25.3−111011
Accu-Chek Aviva Plus311−3.46.3−15915
Walmart ReliOn Confirm (Micro)3172.46.8−101717
CVS Advanced318−0.37.0−131414
FreeStyle Lite312−6.07.4−19919
Accu-Chek SmartView320−5.36.5−17817
Walmart ReliOn Prime3120.49.5−172121
OneTouch Verio3195.96.8−72121
Prodigy AutoCode3121.210.3−172424
OneTouch Ultra 2311−3.09.3−191719
Walmart ReliOn Ultima3193.010.2−162626
Contour Classic320−6.59.7−231323
Solus V2320−10.18.1−23523
Advocate Redi-Code +319−9.110.5−261226
Gmate SMART3205.715.5−224343
  • Modified Bland-Altman analysis compares the difference (BGM reading − reference value) with the reference value rather than comparing the difference with the average of the BGM reading and the reference value. The bias is the average difference as a percent of the reference value. A bias of −5.0% means the BGM meter reading is, on average, 5% lower than the reference value.

  • *SD of the difference in the log-transformed measurements, which is essentially the same as the SD of the % difference = (BGM reading − reference value)/(reference value).

  • †95% limits of agreement define the range around the reference value containing 95% of the BGM readings.

  • ‡Limit boundary with the larger absolute value.