Study design
The present study was part of a prospective nationwide cohort study of MERS survivors conducted at multi-centers in the Republic of Korea. For purposes of this study, a MERS survivor was defined as a patient who was diagnosed with the MERS-CoV infection and then completely recovered, as confirmed by the Korean government during the 2015 outbreak. All subjects were older than 19 years of age at enrollment, voluntarily participated in the study, and answered the questionnaires independently. Of the 148 MERS survivors who were recruited, 73 consented to participate in the study at 6 months post-MERS (Fig. 1). Of these 73 MERS survivors, 69 completed the 12-month assessment, and 63 in five tertiary hospitals provided consent to participate in the cross-sectional psychological assessments at 12 months after the 2015 MERS outbreak, between June 2016 and August 2016: National Medical Center, Seoul National University Hospital, Chungnam National University Hospital, Seoul Medical Center, and Dankook University Hospital. Written informed consent was obtained from all subjects, and the study was approved by the Institutional Review Board of each study hospital.
Measures
All subjects responded to self-report questionnaires assessing sociodemographic characteristics, illness experiences during the MERS-CoV infection period, and psychological features. Questions about MERS-related illness experiences solicited information regarding status during infection, duration of hospitalization, presence of pneumonia, whether a ventilator or extracorporeal membrane oxygenation was applied, and whether a family member died from MERS.
To determine psychological outcomes, PTSD was assessed with the Impact of Event Scale-Revised Korean version (IES-R-K) [14, 15], and depression was evaluated with the Patient Health Questionnaire-9 (PHQ-9) [16, 17]. The IES-R-K is a 22-item scale that assesses symptoms of intrusion, avoidance and numbing, and hyperarousal related to a particular life-threatening event (i.e., MERS-CoV infection in the present study). Each item is rated on a scale ranging from 0 to 4, and a total score ≥ 25 is considered to be clinically significant [15]. The PHQ-9 is a nine-item scale that assesses depression based on the symptoms of major depressive disorder included in the Diagnostic and Statistical Manual of Mental Disorders-fourth edition (DSM-IV) [16]. Significant depression is considered to be present when the total score is > 10 [17].
Current suicidality was assessed with the suicidality module of the Mini-International Neuropsychiatric Interview (K-MINI) [18, 19], which is composed of six weighted items rated as 'yes' or 'no': wish for death (weight of 1), wish for self-harm (weight of 2), suicidal thoughts (weight of 6), suicide plan (weight of 10), suicide attempt in the past 1 month (weight of 10), and lifetime suicide attempt (weight of 4). The suicidality score is the sum of the weighted score of the six items, and a total score ≥ 6 is considered to be above moderate degree of risk. Anxiety was assessed with the Generalized Anxiety Disorder-7 (GAD-7) scale, which consists of seven items rated using a four-point Likert scoring system [20]. A total score ≥ 10 is considered to be significant. The PHQ-9 and the GAD-7 were administered additionally at two points, before and during infection with MERS-CoV, based on participant recall.
Insomnia was evaluated with the Korean version of the Insomnia Severity Index (ISI-K) [21], a five-item measure relying on a five-point scale that assesses current sleep problems and interference with daily functioning; clinical insomnia was considered to be present if the total score was ≥ 15. MERS stigma was assessed with an adjusted version of the 40-item Berger Human Immunodeficiency Virus (HIV) stigma scale [22] and the 8-item short version of the HIV stigma scale [23]. This questionnaire contains eight items rated on a four-point Likert-type scale that ranges from “strongly disagree” to “strongly agree” and assesses the four domains of stigma: personalized stigma, disclosure concerns, negative self-image, and concerns with public attitudes; the Cronbach’s α in the present study was 0.919. The present study also included the Brief COPE, which is a 28-item questionnaire that uses a four-point Likert scale to measure three distinctive coping strategies: emotion-focused, problem-focused, and dysfunctional [24]. The social support systems of participants were assessed with the Medical Outcome Study Social Support Survey (MOS-SSS) [25], which includes 19 items that are scored on a scale from 0 to 100 and assesses emotional/information support, tangible support, positive social interactions, and affectionate support. To examine the impact of social support on mental health in a regression analysis, poor social support was defined as a MOS-SSS score lower than that of the 25th percentile for all participants.
Statistical analysis
The sociodemographic characteristics, MERS-related clinical characteristics, and mental health status of the participants are presented as both numerical values and percentages. The present study placed a particular focus on PTSD and depression, which were the two most prevalent problems 12 months post-MERS in the descriptive analysis. Accordingly, the subjects were divided into two groups based on the presence of significant PTSD or depression. Independent t-tests were conducted to compare the mental health status between the two groups (P < 0.002, adjusted for multiple comparisons), a stepwise regression analysis was performed to identify independent risk factors for PTSD and depression at 12 months after the MERS outbreak, and a univariate analysis was used to identify potential mediating factors associated with PTSD/depression (P < 0.10). Subsequently, a backward multivariate logistic regression analysis was performed using variables identified as significant in the univariate analysis (P < 0.05). Although depression during MERS and current MERS stigma were significant in the univariate analysis, these variables were not entered into the multivariate regression analysis due to multicollinearity with anxiety during MERS (r = 0.831, P < 0.001) and MERS stigma during MERS (r = 0.628, P < 0.001), respectively. All data were analyzed with SPSS for Windows version 21.0 (IBM Corp.; Armonk, NY, USA) except for the multivariate logistic regression analysis, which was performed with STATA version 14.0 (STATA; College Station, TX, USA).