Study participants
A cross-sectional clinical study was adopted to collect the anxiety, sleep status, resilience, fatigue and other demographic data from the participants. Our study enrolled 115 military medical staff from February 17th to February 29th in 2020 by convenience sampling method. All the participants came from Xinqiao Hospital, a military medical hospital in Chongqing, China. 55 FLMS temporarily treating the patients with COVID-19 in Wuhan Huoshenshan Hospital were selected as experimental group and 60 medical staff working in an intensive care unit were selected as control group.
Data collection and measuring instruments
Demographic and social data
Demographic data of our participants included age, gender, profession, marital status, profession, technical title, department, years of work experience, current perceived stress level, current perceived health status, attitude to work in Wuhan, and so on.
The Self-Rating Anxiety Scale (SAS)
The SAS is a self-reported scale made up of 20 items to estimate the subjective anxiety and its changes of individuals, and it covers a variety of anxiety symptoms. Each question was scored 1-4 points. An aggregate score of the 20 items then multiply by 1.25, the integer part is the standard score. The higher the standard scores, the more severe levels of anxiety [17,18]. According to the results of Chinese general population, the SAS total scores of 50 points is normal, 50-59 points is mild anxiety, 60-69 points is moderate anxiety, and more than 69 points is severe anxiety [19].
The Self-Rating Scale of Sleep (SRSS)
The SRSS is a self-reported questionnaire which was tailored for the Chinese population by Chinese psychologists Li [20]. This scale includes 10 items, each statement has five graded answers, respectively scored as 1 to 5, total scores can range from 10 to 50. The aggregate scores of SRSS are classified into normal (scores<23), mild sleep disturbance (scores between 23 and 29), moderate sleep disturbance (scores between 30 and 39), and severe sleep disturbance (scores>39). The reliability (Cronbach’α=0.6418, P<0.001) and validity (r=0.5625, P<0.001) of SRSS have been established.
The Multidimensional Fatigue Inventory (MFI-20)
The MFI-20 is a 20-item self-reported measurement of fatigue. It includes five dimensions: General Fatigue (GF), Physical Fatigue (PF), Mental Fatigue (MF), Reduced Motivation (RM) and Reduced Activity (RA). Every item is rated on a 5-point Likert scale, every subscale’s single total scores are summed up ranging from 4 to 20 scores. Higher total scores indicates higher levels of fatigue. Validity and internal consistency have been verified to be good for different participants [21].
The Connor-Davidson Resilience Scale (CD-RISC)
The CD-RISC is a self-report questionnaire that comprises of 25 items, each rated on a 5-point Likert scale( ranging from 0= “not at all true”, to 4= “true nearly all of the time”), with higher scores reflecting greater resilience. Psychometric evaluation of the CD-RISC conducted on clinical and general population samples found the scale had good reliability (Cronbach’α=0.89), validity, psychometric properties, good internal consistency and test-retest reliability (r=0.87) [22]. Exploratory factor analysis with the Chinese samples resulted in a 3-factor structure of CD-RISC, labeled respectively as Tenacity, Strength and Optimism [23].
Study procedures
Data collection of our study was completed by a Questionnaire Star platform, named Wenjuanxing (http://www.wjx.cn) relying on QR codes in Wechat with anonymity. Two investigators working in Wuhan Huoshenshan Hospital and Xinqiao Hospital respectively explained the research purpose and method to participants, issued the QR code after obtaining consents and collected their relevant data retrospectively. Only volunteers who did not refuse it were enrolled in and they could quit the process at any time. However, we did not get ethic approval because the Huoshenshan Hospital was a temporary hospital with no Clinical Research Ethics Committee.
Hypotheses of SEM
We have set variables bundle based on the literature review, include 4 latent variables and its observed variables of the FLMS working in Wuhan Huoshenshan Hospital: the resilience status, the fatigue status, the physical burden status, the anxiety status. According to the crisis intervention theory, our hypotheses were as follows: ①The resilience had a statistically significant direct negative effect on the anxiety status, physical burden and fatigue status. ②The fatigue status had a statistically significant direct positive effect on the physical burden and anxiety status.③The physical burden had a statistically significant direct positive effect on the anxiety status. ④The fatigue status had a statistically significant indirect positive effect on the anxiety via the physical burden. ⑤The resilience had a statistically significant indirect negative effect on the anxiety via fatigue status, see Fig.1.
Statistical analysis
After checking the date accuracy, IBM SPSS Statistics (Version 22.0) and AMOS (Version 23.0) were applied to complete the data analysis. Descriptive analysis was used to describe the general data, frequencies and percentages were used for count data, and (mean±standard deviation) was used for measurement data. Comparison of difference between groups conducted by independent-sample t-test and analysis of variance (ANOVA). The Maximum Likelihood Estimation was employed for parameter estimation. In SEM, the model fit index of path analysis usually includes the goodness-of-fit index (GFI), the adjusted goodness-of fit-index (AGFI) and so on. In this study, we assumed that the root mean square error of approximation (RMSEA) <0.08, the comparative fit index (CFI) and the normal fit index (NFI)>0.9, the parsimany-adjusted normal fit index (PNFI) and the parsimany-adjusted comparative fit index (PCFI)>0.5 resulted in an acceptable model, when P values<0.05, the difference is considered as statistically significant [24].