4.6. Statistics
Data were analysed with SPSS Statistics version 21 (IBM Corporation, Armonk, NY, USA). Researchers were blinded to the treatment allocation during data analysis. Data were tested for normality using the Shapiro–Wilk test, and data that were not normally distributed are presented as median (25th, 75th percentile). The two regime groups at baseline were compared using the Chi-Squared test for gender, and for the remaining variables a T-test or Wilcoxon signed-rank test for data that were not normally distributed. To test if there was a difference in the change in any outcome variables, an ANCOVA was used. The ANCOVA tested the difference in each outcome variable across four groups, and for each ANCOVA the baseline value of the outcome variable was used as a co-variate. The four groups are outlined in The PRIMER-E software package (Version No.6, Plymouth Marine Laboratories, Auckland, New Zealand) was used to analyse the gut microbiota data, which were analysed at the genus level. Permutational multivariate analysis of variance was used to test the differences between the skin cohort from this study compared to the non-skin cohort from the larger clinical trial to detect any differences at baseline. Permutational multivariate analysis of variance was also used to investigate differences between the three timepoints (baseline, six weeks and twelve weeks) for the two regime groups, creating a total of six groups.Statistical significance was set as Spearman correlations were conducted between the changes in skin measures (PASI, VAS and DQLI) and the changes in gut genera for the participants who were considered responders whilst on the SXRG84 treatment. Correlations were also conducted between skin measures at baseline and gut microbiota genera at baseline.