Table 1.

Mixed-effects meta-regression.

Covariates	Adjusted change in fractional anisotropy (β)	95% CI	Resampled p-value
Patients with carpal tunnel syndrome	− 8.57 × 10–2	− 0.13, − 0.06	0.000
Age in years	− 2.92 × 10–3	− 4.54 × 10–3, − 7.34 × 10–4	0.007
Repetition time (ms)	− 8.98 × 10–6	− 1.14 × 10–5, 6.77 × 10–8	0.053
Number of diffusion sensitising gradient directions	2.27 × 10–3	− 8.39 × 10–4, 2.99 × 10–3	0.271
Echo time (ms) and b-value (mm2/s)*	− 1.51 × 10–8	− 5.27 × 10–7, 4.86 × 10–7	0.936

Adjusted R² = 46%, tau² = 0·0047, I² = 97%.

*Echo time is a function of the b-value as larger b-values mandate relatively longer echo times, so these variables are modelled as the product to minimise the number of covariables, mitigate collinearity and model the interaction between the two variables.