A descriptive analysis of the sociodemographic characteristics of the intervention and control groups was done. Qualitative variables were expressed as percentages, and quantitative variables were summarised as the median and interquartile range.
Shapiro-Wilk tests indicated that the dependent variables were not normally distributed (p < .05), so non-parametric statistical analyses were subsequently performed. The difference between the medians of the two patient groups was examined with the Mann-Whitney U test. Qualitative variables were compared with the chi-squared or Fisher's exact test, as appropriate.
Being a quasi-experimental study, without randomization of patients, the existence of initial pre-intervention differences in the dimensions evaluated by the FIQ scale between the two patient groups was tested with the Mann-Whitney U test. For the dimensions that showed significant pre-intervention group differences, the medians of the post- and pre-intervention differences between the two patient groups were tested. For those dimensions of the FIQ that showed no pre-intervention differences, the post-intervention values were compared. The changes in the FIQ score and its dimensions before and after the intervention in both groups were assessed using the Wilcoxon test.
Additionally, we carried out univariate and multivariate logistic regression analyses to identify the relationships between the independent variables studied and the improvement variable (increase, or not, of at least 8.1 points in the FIQ score after the intervention).
Finally, the sample was stratified by educational level (primary versus secondary/university studies) and age (younger than 60 years or 60+ years). The pre- and post-intervention scores were compared using the Mann-Whitney U test and the differences in each group were analysed with the Wilcoxon test.
