Univariate analyses using ASDAS-ESR as dependent variable | Multivariate analyses using ASDAS-ESR as dependent variable and ADCmax as independent variable (N=70) | Multivariate analyses using ASDAS-ESR as dependent variable and ADCmean as independent variable (N=70) | |||||||

Standard coefficient | Regression coefficient (95% CI) | P value | Standard coefficient | Regression coefficient (95% CI) | P value | Standard coefficient | Regression coefficient (95% CI) | P value | |

Male gender (N=78) | −0.30 | −0.60 (−1.05 to −0.16) | 0.01 | −0.21 | −0.43 (−0.88 to −0.03) | 0.07 | −0.18 | −0.36 (−0.83 to 0.11) | 0.13 |

HLA-B27 positivity (N=77) | −0.31 | −0.82 (−1.40 to −0.24) | 0.01 | −0.23 | −0.63 (−1.23 to −0.02) | 0.04 | −0.23 | −0.62 (−1.22 to −0.01) | 0.05 |

Swollen joint count (N=75) | 0.27 | 0.28 (0.04 to 0.52) | 0.02 | 0.17 | 0.18 (−0.04 to 0.41) | 0.11 | 0.18 | 0.20 (−0.03 to 0.42) | 0.09 |

ADCmax (N=78) | 0.29 | 0.001 (0.00 to 0.002) | 0.01 | 0.24 | 0.001 (0.00 to 0.001) | 0.03 | – | – | – |

ADCmean (N=78) | 0.36 | 0.002 (0.00 to 0.003) | <0.01 | – | – | – | 0.22 | 0.001 (0.00 to 0.002) | 0.05 |

SPARCC spine MRI score (N=74) | 0.26 | 0.03 (0.003 to 0.05) | 0.02 | 0.36 | 0.03 (0.01 to 0.06) | <0.01 | 0.36 | 0.03 (0.01 to 0.06) | <0.01 |

Age (N=78) | 0.12 | 0.01 (−0.01 to 0.03) | 0.29 | – | – | – | – | – | – |

Smoker (N=78) | 0.11 | 0.23 (−0.23 to 0.68) | 0.33 | – | – | – | – | – | – |

Drinker (N=78) | 0.13 | 0.39 (−0.29 to 1.07) | 0.25 | – | – | – | – | – | – |

Duration of back pain (N=77) | −0.08 | −0.01 (−0.03 to 0.01) | 0.51 | – | – | – | – | – | – |

Family history of SpA (N=75) | 0.13 | 0.31 (−0.24 to 0.86) | 0.26 | – | – | – | – | – | – |

Tender joint count (N=75) | 0.17 | 0.11 (−0.04 to 0.25) | 0.14 | – | – | – | – | – | – |

Ever enthesitis (N=78) | 0.10 | 0.19 (−0.25 to 0.62) | 0.40 | – | – | – | – | – | – |

nADCmax (N=78) | −0.02 | −0.01 (−0.12 to 0.10) | 0.85 | – | – | – | – | – | – |

nADCmean (N=78) | 0.08 | 0.08 (−0.15 to 0.31) | 0.49 | – | – | – | – | – | – |

SPARCC SI MRI score (N=67) | 0.11 | 0.02 (−0.03 to 0.07) | 0.38 | – | – | – | – | – | – |

ADC, mean apparent diffusion coefficient; ADC, apparent diffusion coefficient; ASAS, Assessment of Spondyloarthritis International Society; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; HLA, human leucocyte antigen; N, number; SI, sacroiliac; SPARCC, Spondyloarthritis Research Consortium of Canada; SpA, spondyloarthritis; nADCmax, normalised maximum apparent diffusion coefficient; nADCmean, normalised mean apparent diffusion coefficient.