Table 1.

Bland–Altman analysis of agreement between measures

StudyComparisonRatio (95% CI)Range of agreement (ratio ± 2 SD)
A. Comparison between testing sites
Study 4UCSF vs. UT plasma 3-HC0.95 (0.89–1.02)0.74–1.22
UCSF vs. UT plasma COT0.89 (0.84–0.94)0.72–1.10b
UCSF vs. UT plasma NMR1.06 (0.99–1.13)0.84–1.34b
B. Comparison between NMR derived from total vs. free 3-HC
Study 4Urine total vs. free NMR1.21 (1.18–1.25)1.02–1.45
C. Comparison between biomarkers in various body fluids of smokers
Study 2Blood vs. plasma 3-HC0.97 (0.90–1.04)0.64–1.48b
Blood vs. plasma COT0.96 (0.91–1.01)0.69–1.32
Blood vs. plasma NMR1.01 (0.95–1.06)0.72–1.40b
Blood vs. saliva 3-HC0.96 (0.84–1.11)0.44–2.13
Blood vs. saliva COT0.91 (0.83–1.00)0.53–1.56
Blood vs. saliva NMR1.04 (0.95–1.15)0.61–1.78b
Urine vs. blood 3-HCa40.7 (30.7–54.1)7.6–217.8
Urine vs. blood COT4.8 (4.1–5.6)1.94–11.9
Urine vs. blood NMRa8.5 (7.1–10.2)2.89–24.8
Saliva vs. plasma 3-HC1.49 (0.87–1.15)0.45–2.23
Saliva vs. plasma COT1.04 (0.95–1.14)0.63–1.73
Saliva vs. plasma NMR0.96 (0.86–1.07)0.52–1.77
Urine vs. plasma 3-HCa38.2 (28.9–50.5)7.5–194.0
Urine vs. plasma COT4.6 (4.0–5.3)2.05–10.3
Urine vs. plasma NMRa8.5 (7.1–10.1)2.96–24.1
Urine vs. saliva 3-HCa36.4 (27.1–46.6)6.9–190.8
Urine vs. saliva COT4.3 (3.7–5.0)1.89–9.8
Urine vs. saliva NMRa8.6 (6.9–10.6)2.60–28.2
D. Comparison between saliva and plasma in smokers and nonsmokers
Study 3Saliva vs. plasma 3-HCa0.87 (0.81–0.95)0.44–1.75
Saliva vs. plasma COT1.01 (0.94–1.08)0.55–1.85
Saliva vs. plasma NMRa0.88 (0.83–0.94)0.53–1.47

NOTE: Ratio, back-transformation of mean difference between measures on log-scale; 95% CI of ratio, back-transformation of 95% CI of the mean difference between measures on log-scale; range of agreement, back-transformation of the mean difference between measures on a log-scale ± 2 SDs from the mean difference.

  • aUrine total 3-HC was used in analysis.

  • bMeasures are consistently similar, that is, measures were not observed outside the limit of agreement of mean bias ± 2 SDs.