Work-related stress is a public health issue. Among the multiple physical and psychological consequences of stress, increased mortality and cardiovascular morbidity seem the main concern. The thermal spa resort of Néris-Les-Bains is one of the five spa resorts in France specialized in the treatment of psychosomatic disorders. Among all these resorts proposing a thermal residential program of three weeks, only one thermal spa resort (Saujon) has a program for occupational burn-out. However, a shorter thermal spa residential program seems more compatible with professional context (availability of individuals), and focusing on work-related stress prevention (before the state of burn-out).

The main hypothesis is that a short thermal spa residential program (6 days) of work-related stress prevention will exhibit its efficacy through objective measures of well-being and cardiovascular morbidity.

The Therm-Stress protocol was designed to provide a better understanding of the effect of a short spa residential program of work-related stress prevention on the improvement of heart rate variability.

In the present protocol, parameters are measured on six occasions (inclusion, 6 days before the start, at the start of the spa, at the end of the spa, at 6 months and at 12 months).

Statistical analysis will be performed using Stata software (version 13; Stata-Corp, College Station, Tex., USA). All statistical tests will be two-sided and p<0.05 will be considered significant. After testing for normal distribution (Shapiro-Wilk test), data will be treated either by parametric or non-parametric analyses according to statistical assumptions. Inter-groups comparisons will systematically be performed 1) without adjustment and 2) adjusting on factors liable to be biased between groups.

Analysis will be performed using anova or Kruskal-Wallis (KW) tests. When appropriate (p<0.05), a post-hoc test for multiple comparisons (Tukey-Kramer after anova and Dunn post KW) will be used. Linear regression (with logarithmic transformation if necessary) considering an adjustment on covariates fixed according to epidemiological relevance and observance to physical activity will complete the analysis.

Comparisons of categorical variables will be performed using Chi-squared or Fischer test. Marascuillo's procedure will be performed for multiple comparisons. Relations between quantitative outcomes will be analyzed using correlation coefficients (Pearson or Spearman). Fisher's Z transformation and William's T2 statistic will be performed to compare correlations between variables and within a single group of subjects. Longitudinal data will be treated using mixt-model analyses in order to treat fixed effects group, time and group x time interaction taking into account between and within participant variability.

Inclusion Criteria:

• Workers with a visual analog scale of stress greater than 50 mm
• from 18 years to retirement
• written informed consent
• Affiliation to French health care system (for France)

Exclusion Criteria:

• Participant refusal to participate

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