Statistical analysis
LBP, NRS
Differences between the intervention and control groups for continuous variables were evaluated based on the results of the Shapiro–Wilk test using the t-test or Mann–Whitney U test. Nominal variables used the chi-squared test or Z-test. Two points was considered a clinically important change on the NRS. First, the percentages of participants with an NRS score of at least two points at baseline were compared. Then, the percentages of participants with improvements of at least two points on the NRS were compared from baseline to three months later between the intervention and control groups using the chi-squared test.Using the Wilcoxon signed-rank test, changes in NSLBP over the past four weeks, as measured by the NRS score and EQ-5D utility value, were compared from baseline to three months later separately in the intervention and control groups. Next, the analysis of covariance (ANCOVA) was performed to investigate NRS interactions from baseline to three months later in the intervention and control groups. The covariate for ANCOVA was the presence or absence of LBP over the past year.Statistical analyses were performed using IBM SPSS Statistics, ver. 24 (IBM Corp., Armonk, N.Y., USA), with a significance level of 5%.