Demographic and working characteristics and fatigue
The characteristics of the sample and the group comparisons on fatigue are presented in Table 1. Most HCWs were female (65.3%) and married (80.8), obtained the degree of university or above (67.2%), worked 10 years or less. The mean age of 527 HCWs was 34.86 (SD=8.67), ranging from 20 to 58 with 294 (55.8%), 178 (33.8), 55 (10.4) respondents reporting junior, intermediate and senior technical title respectively.
The prevalence of fatigue among HCWs was 56.7% (FS-14 ≥ 7). There was significant difference in fatigue among different age groups (F = 3.176, P =0.024). LSD post hoc test indicated HCWs aged 30-39 years presented significant higher fatigue than those aged 20-29 years and those aged 50-59 (all P < 0.05). No significant differences were found in fatigue by gender, marital status, education, years of working and technical title (all P > 0.05).
<Table 1 was inserted here>
Bivariate correlations between all the study variables
As presented in Table 2, self-efficacy was negatively correlated with PTSD symptoms (r = -0.301, P < 0.001) and fatigue (r = -0.402, P < 0.001). PTSD symptoms were positively associated with negative coping (r = -0.336, P < 0.001) and fatigue (r = -0.402, P < 0.001). In addition, negative coping was positively related to fatigue (r = 0.143, P < 0.01). However, there was no significant association between self-efficacy and negative coping (P > 0.05).
<Table 2 was inserted here>
Mediating effect of PTSD symptoms
The study assumed PTSD symptoms would mediate the relationship between self-efficacy and fatigue. We followed Mackinnon’s four-step procedure to examine the mediation effect (see Table 3). Firstly, self-efficacy was significantly associated with fatigue (β = 0.40, P＜0.001) (see Model 1 in Table 3). Secondly, self-efficacy was significantly related to PTSD symptoms (β = 0.30, P＜0.001) (see Model 2 in Table 3). Thirdly, PTSD symptoms were significantly correlated with fatigue when we controlled for self-efficacy (β = 0.50, P＜0.001) (see Model 3 in Table 3). Finally, the indirect effect of self-efficacy on fatigue via PTSD symptoms was significant (ab = -0.15, SE = 0.03, 95% CI = [-0.21, -0.10]). The mediation effect accounted for 37.7% of the total effect. In sum, all four criteria for mediation effect have been met and PTSS symptoms mediated the effect of self-efficacy on fatigue of HCWs during the COVID-19 pandemic.
<Table 3 was inserted here>
Moderated Mediation effect analysis
The study anticipated negative coping might play as a moderator in the direct and indirect (the first stage of the mediation pathway: self-efficacy – PTSD symptoms) effects of self-efficacy on fatigue. As presented in Table 4, the results of moderated mediation analysis showed the interaction of self-efficacy and negative coping had a significant effect on PTSD symptoms (β = -0.158, P＜0.001), which indicated that the relation between self-efficacy and PTSD symptoms was moderated by negative coping. The moderated mediation effect was established since the indirect pathway was moderated by negative coping . Additionally, negative coping also moderated the direct effect of self-efficacy on fatigue (β = 0.075, P＜0.05).
<Table 4 was inserted here>
Table 4 also showed the conditional direct and indirect effects of self-efficacy on fatigue at different values of negative coping (1 SD below the mean, the mean, and 1SD above the mean). The direct effect of self-efficacy on fatigue was stronger at 1 SD below the mean of negative coping (β= -0.306, 95%CI: -0.391, -0.221) than 1SD above the mean (β= -0.157, 95%CI: -0.256, -0.058). As shown by Johnson-Neyman technique , negative coping would moderate the direct effect of self-efficacy on fatigue when the standard scores of negative coping were lower than 1.494, in which 95% CI did not contain zero (see Figure 2).
<Figure 2 was inserted here>
Nonetheless, the indirect effect of self-efficacy on fatigue was attenuated at 1 SD below the mean of negative coping (β= -0.090, 95%CI: -0.141, -0.051) in comparison to 1SD above the mean (β= -0.256, 95%CI: -0.332, -0.188). Johnson-Neyman technique presented that negative coping would moderate the association between self-efficacy and PTSD symptoms when the standard scores of negative coping were more than -1.401 as 95% CI did not include zero (see Figure 3).
<Figure 3 was inserted here>