Table 1.
Technical reproducibility and temporal variability of serum bile acids and short chain fatty acids.
| SERUM | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Baseline visit | Duplicate | Reproducibility | 6-month visit | Temporal variability | |||||||
| Bile acid | Na | NNQb | Na | NNQb | CVc | ICC | 95 % CI | Na | NNQb | ICC | 95 % CI |
| Chenodeoxycholic | 136 | 0 | 50 | 0 | 2.9% | >0.99 | (>0.99, >0.99) | 50 | 0 | 0.31 | (0.10, 0.54) |
| Cholic | 136 | 0 | 50 | 0 | 4.1% | >0.99 | (>0.99, >0.99) | 50 | 0 | 0.28 | (0.06, 0.57) |
| Deoxycholic | 136 | 2 | 50 | 0 | 2.4% | >0.99 | (>0.99, >0.99) | 50 | 1 | 0.51 | (0.30, 0.75) |
| Glycochenodeoxycholic | 136 | 0 | 50 | 0 | 4.7% | >0.99 | (>0.99, >0.99) | 50 | 0 | 0 | (0.00, 0.32) |
| Glycocholic | 136 | 0 | 50 | 0 | 6.5% | >0.99 | (0.99, >0.99) | 50 | 0 | 0.22 | (0.00, 0.64) |
| Glycodeoxycholic | 136 | 1 | 50 | 0 | 3.3% | >0.99 | (>0.99, >0.99) | 50 | 1 | 0.29 | (0.03, 0.68) |
| Glycolithocholic | 136 | 1 | 50 | 0 | 9.1% | 0.99 | (0.96, >0.99) | 50 | 1 | 0.37 | (0.12, 0.62) |
| Glycoursodeoxycholic | 136 | 0 | 50 | 0 | 5.5% | >0.99 | (>0.99, >0.99) | 50 | 0 | 0.50 | (0.30, 0.67) |
| Lithocholic | 136 | 4 | 50 | 2 | 8.1% | 0.99 | (0.98, 0.99) | 50 | 3 | 0.57 | (0.42, 0.79) |
| Taurochenodeoxycholic | 136 | 1 | 50 | 0 | 5.4% | >0.99 | (>0.99, >0.99) | 50 | 0 | 0.28 | (0.06, 0.54) |
| Taurocholic | 136 | 2 | 50 | 0 | 5.2% | >0.99 | (>0.99, >0.99) | 50 | 1 | 0.44 | (0.16, 0.66) |
| Taurodeoxycholic | 136 | 7 | 50 | 2 | 7.9% | 0.99 | (0.97, >0.99) | 50 | 1 | 0.38 | (0.15, 0.59) |
| Ursodeoxycholic | 136 | 33 | 50 | 9 | 20.8% | 0.89 | (0.79, 0.98) | 50 | 4 | 0.34 | (0.06, 0.57) |
| Taurolithocholic | 136 | 14 | 50 | 5 | 13.4% | 0.88 | (0.73, >0.99) | 50 | 11 | 0.16 | (0.00, 0.43) |
| Tauroursodeoxycholic | 136 | 51 | 50 | 10 | 40.6% | 0.72 | (0.50, 0.89) | 50 | 16 | 0.38 | (0.17, 0.54) |
| Short chain fatty acid | |||||||||||
| 2-Methylbutyric | 136 | 0 | 50 | 0 | 18.8% | 0.56 | (0.41, 0.79) | 50 | 0 | 1.00d | -- |
| Acetic | 136 | 0 | 50 | 0 | 7.2% | 0.97 | (0.95, 0.99) | 50 | 0 | 0.06 | (0.00, 0.24) |
| Butyric | 136 | 0 | 50 | 0 | 7.1% | 0.97 | (0.95, 0.98) | 50 | 0 | 0.39 | (0.17, 0.56) |
| Hexanoic | 136 | 0 | 50 | 0 | 11.2% | 0.81 | (0.69, 0.88) | 50 | 0 | 0.23 | (0.00, 0.47) |
| Isobutyric | 136 | 0 | 50 | 0 | 13.2% | 0.64 | (0.37, 0.77) | 50 | 0 | 0.53 | (0.23, 0.66) |
| Isovaleric | 136 | 0 | 50 | 0 | 10.8% | 0.91 | (0.87, 0.94) | 50 | 0 | 0.25 | (0.00, 0.54) |
| Propionic | 136 | 0 | 50 | 0 | 20.7% | 0.81 | (0.74, 0.88) | 50 | 0 | 0.43 | (0.20, 0.61) |
| Valeric | 136 | 0 | 50 | 0 | 10.7% | 0.93 | (0.89, 0.96) | 50 | 0 | 0.58 | (0.37, 0.72) |
Abbreviations: NQ, not quantifiable; CV, coefficient of variation; ICC, intraclass correlation coefficient; CI, confidence interval.
a
N denotes the total number of samples used in the analysis
b
NNQ denotes samples for which concentrations were not quantifiable and were replaced by ½ lowest observation value for a given analyte and sample type except for fecal taurolithocholic and tauroursodeoxycholic
c
CV is estimated as the mean value of CVs from sample duplicates
d
ICC reliability over time is estimated as 1. This may be because the ICC reproducibility is low, so it can inflate the ICC variability over time.