In total, 70 university students (Mage = 23.34, SDage = 3.11; 87.1% female) exposed to various traumatic experiences were included in the trial and were randomly allocated to intervention (n = 31) or control (n = 39) group. The power analysis revealed that the total sample of 66 participants was sufficient to detect the effect sizes of 0.25, indicating the differences between the two groups by using the multivariate two-measures data analytic approach (given a significance level of .05 and a power of 80%). Descriptive data on study participants at the pre-test are presented in Table 1. No differences were observed in terms of demographic characteristics between the groups, except for gender. There were significantly more male participants in the intervention group as compared to the control group (see Table 1).
We included participants who met the following criteria: (1) were 18 years old or older; (2) were fluent in the Lithuanian language; (3) had access to a device with an internet connection; (4) had experienced at least one traumatic event in their lifetime; (5) met the clinical significance criteria for PTSD, CPTSD, or DSO only with or without functional impairment as measured with the International Trauma Questionnaire (Cloitre et al., 2018). Participants without functional impairment were included in the study regardless, given the fact that the study was carried out during the beginning of the COVID-19 pandemic, and therefore, functional impairment in social, occupational, and other areas might have been affected significantly due to the context of the pandemic. The pre-defined exclusion criteria were as follows: (1) current acute case of psychiatric care; (2) currently experienced ongoing interpersonal violence; (3) current abuse of alcohol or drugs. None of the participants met the exclusion criteria. In addition, a suicidal crisis intervention plan was prepared, which included contacting study participants via phone call and directing them to crisis assistance services in a community. However, there were no participants with suicidal risk in the study.
Participants’ Exposure to Traumatic Events. The exposure to traumatic events at the pre-test is presented in Table 2. No differences were found between the intervention and waiting list control groups regarding the mean score of experienced traumatic events. Also, there were no differences in exposure to specific traumatic events, except for life-threatening illness or injury, which was significantly more often reported in the intervention group than in the control group. The most prevalent traumatic event types both in the intervention and control groups were severe human suffering (exposure rate over 70%) and childhood physical abuse (exposure rate over 50%). The index trauma of the participants from the intervention and control groups were as follows: death of someone close (25.8% vs. 17.9%), sexual trauma (16.1% vs. 12.8%), physical abuse (12.9% vs. 20.5%), serious illness (9.7% vs. 7.7%), psychological abuse (9.7% vs. 17.9%), transportation accident (0% vs. 2.6%), several traumatic events (0% vs. 2.6%), and other traumatic events (25.8% vs. 17.9%). The time when the traumatic event occurred varied both in the intervention and control groups: exposure less than 6 months ago (16.1% vs. 23.1%), 6–12 months ago (12.9% vs. 12.8%), 1–5 years ago (29.0% vs. 28.2%), 5–10 years ago (12.9% vs. 15.4%), 10–20 years ago (22.6% vs. 17.9%), and more than 20 years ago (6.5% vs. 2.6%).
Intervention-Control Comparison. Descriptive information on participants’ PTSD and DSO symptom scores as well as depression symptom scores, anxiety symptom scores, and positive mental health scores at the pre-test are presented in Table 3. The t-tests showed no significant differences between the intervention and waiting list control groups at pre-test for any primary or secondary outcomes. No differences were found on PTSD symptoms (t(68) = 1.55, p = .125) or DSO symptoms (t(68) = − 0.02, p = .983). Also, no differences were found between the two groups for depression symptoms (t(68) = 0.62, p = .538), anxiety symptoms (t(68) = 0.35, p = .724), and positive mental health (t(68) = 0.94, p = .350). In the intervention group, 9.7% (n = 3) of the participants met criteria for diagnostic status of PTSD, and 38.7% (n = 12) of the participants met criteria for diagnostic status of CPTSD. In the control group, 25.6% (n = 10) of the participants met criteria for diagnostic status of PTSD, and 46.2% (n = 18) of the participants met criteria for diagnostic status of CPTSD. There were no differences between the intervention and control groups in terms of current mindfulness practices (3.2% vs. 5.1%; χ2(1) = 0.15, p = .696), current visits to a psychologist (19.4% vs. 12.8%; χ2(1) = 0.56, p = .456), and current use of medicine due to mental health problems (19.4% vs. 30.8%; χ2(1) = 1.18, p = .278). In the context of the COVID-19 pandemic, participants were also asked about their experiences related to COVID-19. None of the participants were or had been infected with coronavirus. None of the participants from the control group had a close family member or friend infected; there was one such case in the intervention group.
Data were collected at two timepoints, March to April (pre-test/T1) and June to July (post-test/T2) 2020. Information about the study and the invitation to participate was sent by academic e-mail to all students at one of the largest research-oriented comprehensive Lithuanian universities and posted on the University’s Facebook page. In addition, information was announced via University Students’ Representation which posted information on separate faculties’ Facebook pages and encouraged students to participate in the study by sending them additional e-mails. Individuals interested in participation registered on the study website (www.stillme.lt) and completed the pre-test measures. After registration, individuals who had completed all the required measures were contacted for a structured phone interview. Inclusion was finalized after the phone interviews. A flowchart of the inclusion in the study is presented in Fig. 1.
Participants who met all inclusion criteria and had completed the pre-test measures were randomly assigned to either the intervention or waiting list control group. Randomization was based on a computer-generated randomization list (www.random.org) and was performed by an independent researcher. No stratification was applied. Participants were informed that they would be randomly allocated to either the intervention or waiting list control group. Participants assigned to the intervention group started using the program right after the randomization, whereas participants assigned to the waiting list control group were informed that they would get access to the program in 5 months.
All data reported in the trial were collected online, and participants were given standardized reminders to complete the assessments using the online assessment system. The study was approved by Vilnius University Psychology Research Ethics Committee (Reference No. 27-02-2020/36). All participants gave their informed consent for participation before filling the pre-test questionnaires. In the current study, the data are reported following the CONSORT statement for reporting parallel group trials (Schulz et al., 2011).
Intervention. A mindfulness-based internet intervention was developed specifically for the current study. It was aimed at university students who had been exposed to traumatic life events and experienced PTSD or CPTSD symptoms. The intervention was designed as a self-help program with the possibility of sending messages to a psychologist. The program was delivered through a secure online platform Iterapi (Vlaescu et al., 2016), which had been used in many previous studies, and translated into Lithuanian. The content of the intervention was developed by a team of psychologists, based on mindfulness principles with a focus on psychoeducation (which explicitly addressed traumatic experiences as well as PTSD and CPTSD symptoms followed by mindfulness benefits) and mindfulness techniques training. Eight modules included: (1) Introduction, (2) Awareness and nonjudgment of physical senses, (3) Physical senses in everyday life, (4) Awareness and nonjudgment of thoughts, (5) Thoughts in everyday life, (6) Awareness and nonjudgment of emotions, (7) Emotions in everyday life, and (8) Summary. The content of the program is presented in Table 4. Each module consisted of psychoeducation, two or three mindfulness exercises, and a reminder of the possibility to contact the psychologist. The mindfulness exercises were provided as audio recordings. The length of the audio recordings was approximately 2 to 7 minutes. Participants had the possibility to download each of the audio recordings to their devices. Participants could choose the intensity of the program according to their personal needs but were encouraged to practice at least one exercise every day. Access to a new module was provided every week on the same weekday over the 8 weeks. Once accessible, modules remained available throughout the intervention.
Two clinical psychologists and one Master’s student in the Clinical psychology program were involved as psychologists in the study. They received special training according to the guidelines developed specifically for the study. Weekly supervision meetings were scheduled, and extra supervisions were provided on request. The psychologist’s role included supporting the participants, offering feedback, and answering questions. The psychologist’s feedback was largely standardized, but individualization was encouraged to fit specific questions of the participants. Participants communicated with the psychologists asynchronously by writing and uploading their texts within a secure platform (Vlaescu et al., 2016), while psychologists provided feedback subsequently within 24 h. In total, psychologists wrote 15 texts of feedback to 8 participants of the study; other participants did not contact psychologists. Each feedback from psychologists took from 10 to 60 min.
Exposure to Traumatic Experiences. The DSM-5 Life Events Checklist (LEC-5) (Weathers et al., 2013) was used to assess the lifetime exposure to 18 traumatic experiences such as physical or sexual assault, life-threatening illness, or injury with one additional item assessing any other extremely stressful life event. The type of exposure to traumatic events was assessed with five possible response options: 1 (= “happened to me”), 2 (= “witnessed it”), 3 (= “learned about it”), 4 (= “not sure”), and 5 (= “does not apply”). In the current study, exposure to traumatic experience was considered if participants reported that traumatic experience either happened to them (1) or they witnessed it (2). The Lithuanian version of the measure has been used in previous research (Kazlauskas et al., 2018).
Symptoms of PTSD and CPTSD. The International Trauma Questionnaire (ITQ) (Cloitre et al., 2018), based on the WHO ICD-11 principles for PTSD and CPTSD diagnosis, was used to measure PTSD and CPTSD symptoms. Participants were instructed to indicate an experience based on DSM-5 Life Events Checklist (LEC-5; Weathers et al., 2013) that affected them the most, to briefly describe it, and provide responses to the ITQ regarding that traumatic experience. The ITQ is comprised of 18 items. Six items, two for assessment of each of the three PTSD symptom clusters in the past month, are divided into three subscales: two items for re-experiencing, two items for avoidance, and two items for a sense of threat symptoms. The score of the ITQ PTSD symptom part has a range from 0 to 24. The DSO symptoms in the past month are also measured with the six symptom items on the three subscales, in particular, affective dysregulation, negative self-concept, and disturbances in relationships symptoms, with two items for each of the DSO symptom clusters. The score of the ITQ DSO part has a range from 0 to 24. Additional six functional impairment items of the ITQ assess how PTSD (three items) and DSO (three items) symptoms impaired functioning in the past month. Participants rate the ITQ items on a 5-point Likert scale ranging from 0 (= “not at all”) to 4 (= “extremely”). A score of ≥ 2 for at least one of the two items representing a particular PTSD and DSO symptom cluster indicates clinical significance based on the diagnostic algorithm proposed by the authors of the ITQ (Cloitre et al., 2018). A probable PTSD diagnosis is given when all three PTSD symptoms are clinically significant and if they significantly impair their functioning in at least one area of life. Diagnosis of CPTSD requires that the diagnostic criteria for PTSD are met, all three symptom clusters of DSO are clinically significant, and DSO symptom-related significant functional impairment in at least one area in life is reported. In the current sample, the internal consistency was high for the full ITQ scale (Cronbach’s alpha, α = .82) and acceptable for the subscales of PTSD symptoms (α = .75) and DSO symptoms (α = .68).
Depression. Patient Health Questionnaire-9 (PHQ-9) (Kroenke et al., 2001) was used to measure symptoms of depression. The Lithuanian version of PHQ-9 was used (Montvidas, 2018). Participants rate the statements on a 4-point Likert scale ranging from 0 (= “not at all”) to 3 (= “nearly every day”) by assessing whether they have been bothered by the loss of interest in doing things, fatigue, appetite problems, negative depressive thoughts within the last 2 weeks. The total score of PHQ-9 has a range from 0 to 27. The 10th item assesses how these problems impede work (from 0 = “not difficult at all” to 3 = “extremely difficult”). In the current study, good internal consistency of the PHQ-9 (α = .80) was found.
Anxiety. The Generalized Anxiety Disorder Scale‐7 (GAD-7) (Spitzer et al., 2006) was used to measure anxiety symptoms. The Lithuanian version of GAD-7 was used (Butkutė-Šliuožienė, 2019). GAD-7 measures general anxiety symptoms over the past two weeks. Seven statements (such as “Not being able to stop or control worrying”) are scored on a Likert scale from 0 (= “not at all”) to 3 (= “nearly every day”). The total score of GAD-7 has a range from 0 to 21. In the current study, Cronbach’s alpha of the full scale was high (α = .90).
Positive Mental Health. Positive Mental Health Scale (PMH) (Lukat et al., 2016) was used to assess positive mental health. The PMH comprises nine items measuring the emotional, cognitive, and social aspects of positive mental health. Participants rated statements such as “In general, I am confident,” “Much of what I do brings me joy,” on a Likert scale from 0 (= “do not agree”) to 3 (= “agree”). The total score of PMH has a range from 0 to 27. The Lithuanian version of the scale has been used in previous research and demonstrated good psychometric characteristics (Truskauskaite-Kuneviciene et al., 2020). In the current study, Cronbach’s alpha of the full scale was high (α = .84).
User Satisfaction and Program Usability. Six items were used to assess satisfaction with using the program and program usability. The participants in the intervention group were asked to rate how useful (from 1 = “not useful at all” to 5 = “very useful”), satisfactory (from 1 = “I didn’t like it at all” to 5 = “I liked it a lot”), and easy to use (from 1 = “it was not easy at all” to 5 = “it was very easy”) the program was. They were also asked to report their subjective impression regarding the improvement of mental well-being (from 1 = “worsened a lot” to 5 = “improved a lot”), general understanding of oneself and one’s well-being (from 1 = “not at all” to 5 = “definitely yes”), and recommending the program to a person who had experienced a traumatic event in their lifetime (from 1 = “not at all” to 5 = “definitely yes”).
Since we aimed to capture the possible change in used constructs, we performed a series of multivariate repeated measures ANOVAs with time (pre-test and post-test) as a within-subject factor and group (intervention vs. control) as a between-subject factor. First, we tested the intervention effects on PTSD and DSO symptoms using the sum scores for each measure. Then, we separately tested the PTSD symptoms subscales of re-experiencing, avoidance, and sense of threat. We also performed an analysis of the DSO symptoms subscales of affective dysregulation, negative self-concept, and disturbances in relationships. Finally, we tested the secondary outcomes (depression, anxiety, and positive mental health) using the sum scores of the respective measures.
We calculated both within-group and between-group effect sizes. The between-group effect sizes were calculated using the mean difference from pre-test to post-test in the intervention and control groups and the standard deviations of each group at pre-test (Morris, 2008). The within-group effect sizes were calculated using the means in each group at pre-test and post-test and standard deviations at each measurement point. Bias-corrected effect sizes (Fritz et al., 2012) were reported. The magnitude of the effect expressed in d was interpreted according to Cohen (1988), that is, 0.50 = medium effect, and 0.80 = large effect.
We used the Reliable change index (RCI) to calculate clinically significant changes (Iverson, 2019). For RCI calculations, we used the PTSD and CPTSD sum scores, standard deviations of the pre-test in the intervention group, and test-retest reliability of the respective scale. Independent samples t-test and χ2-test were used to test for between-group differences on demographic characteristics, trauma exposure prevalence, primary and secondary outcomes. Data analyses were performed using IBM SPSS Statistics version 26.