The goals of the study are to investigate the effects of mindfulness-based stress reduction (MBSR) on PTSD among road traffic accident victims. The main questions are: does MBSR exerts any effects on PTSD symptoms, quality of life and mindfulness?

Researchers will compare effects of MBSR with TAU on PTSD symptoms, quality of life and mindfulness.

Participants will be:

• administered few questionnaires at three time points
• administered MBSR once a week session for 6 weeks

Problem Statement and Gap of Knowledge:

Posttraumatic stress disorder (PTSD) is a serious mental health condition that can develop both immediately after and long after exposure to an extraordinary traumatic event. According to relevant literature, the prevalence of PTSD among road traffic victims is very high. Some scholars have pointed out that the incidence of PTSD symptoms among traffic accident victims may be as high as 25%(Miller, Millar, & Davis, 2012). Some clinical studies have even shown that the incidence of PTSD in this group is 7.53%(Ye et al, 2009).Almost all PTSD patients experience great suffering, which often leads to significant impairment of daily bodily functions, social relationships and overall quality of life, thus triggering long-term and persistent psychological, physical and social consequences. Drug therapy and cognitive behavioural therapy (CBT) are currently the most commonly used traditional treatments in clinical practice to relieve PTSD symptoms. However, these treatments have revealed more limitations in clinical practice, such as drug side effects and limited treatment effects on patients(Stewart & Stotts, 2009). In addition, cognitive behavioural therapy (CBT) is confrontational in its treatment approach, which requires patients to confront traumatic memories. This can be extremely challenging for those patients who have difficulty regulating their emotions or who experience post-traumatic dissociation(Foa, Hembree & Rothbaum, 2005).

Because we have encountered all these problems in clinical treatment, we urgently need to explore more advantageous treatment methods that we hope will more effectively relieve symptoms of post-traumatic stress disorder (PTSD), reduce the impact of comorbid symptoms, and improve psychological resilience and quality of life in the long term. This has become the core issue in the current research field of PTSD. There is sufficient evidence to show that mindfulness-based stress reduction (MBSR) can effectively treat a variety of mental health problems, including PTSD, and has achieved good treatment results(Kabat-Zinn,1990). Although some studies have explored the effectiveness of mindfulness-based stress reduction (MBSR) in the treatment of post-traumatic stress disorder (PTSD), there is currently a lack of research focusing on the long-term efficacy and mechanism of MBSR in the group of road traffic accident victims. Especially in modern society, where the number of vehicles is increasing rapidly, the number of PTSD cases caused by traffic accidents is also on the rise. Therefore, it is particularly important to explore ways to adapt MBSR treatment methods to the needs of this special group.

Rationale/ Justification of study:

This study aims to measure the efficacy of mindfulness-based stress reduction (MBSR) on post-traumatic stress disorder (PTSD) in road traffic accident victims, to provide a more effective practical method for alleviating the condition of patients with post-traumatic stress disorder (PTSD). This study will demonstrate and provide a theoretical basis for the effectiveness of mindfulness-based therapy for PTSD patients, particularly road accident victims to enhance the degree of mindfulness when facing traumatic events through MBSR. However, research on PTSD and mindfulness therapy is still lacking. Therefore, it is very meaningful to explore the impact of mindfulness-based stress reduction (MBSR) on the efficacy of PTSD patients, particularly in road traffic accident victims where data is scarce.

Research Question(s) :

1. Is mindfulness-based stress reduction (MBSR) effective to alleviate symptoms of post-traumatic stress disorder compare to treatment-as-usual (TAU) control subjects among road traffic accident victims across time?
2. Is mindfulness-based stress reduction (MBSR) effective in enhancing the degree of mindfulness compare to treatment-as-usual (TAU) control subjects among road traffic accident victims across time?
3. Is mindfulness-based stress reduction (MBSR) effective in improving the quality of life compare to treatment-as-usual (TAU) control subjects among road traffic accident victims across time?

Research Hypothesis(es) :

1. (Null hypothesis): Mindfulness-based stress reduction (MBSR) does not reduce symptoms of posttraumatic stress disorder (PTSD) among road traffic accident victims across time.

   (Alternative hypothesis): Mindfulness-based stress reduction (MBSR) is more effective than the TAU control group in reducing symptoms of post-traumatic stress disorder (PTSD) among road traffic accident victims across time.

2. (Null hypothesis): MBSR does not enhance the degree of mindfulness among road traffic accident victims across time.

   (Alternative hypothesis): MBSR is more effective than TAU control group in enhancing the degree of mindfulness among road traffic accident victims across time..

3. (Null hypothesis): MBSR does not improve the quality of life among road traffic accident victims across time.

(Alternative hypothesis): MBSR is more effective than TAU control group in improving the quality of life among road traffic accident victims across time.

Research Objective(s) :

1.6.1 General objectives To evaluate the effectiveness of MBSR to treat symptoms of post-traumatic stress disorder (PTSD) (primary outcome) and improve mindfulness and the quality of life (secondary outcomes) among road traffic accident victims across time.

1.6.2 Specific Objectives

1. To compare the rate of change in the severity of PTSD symptoms between the MBSR group and TAU control group across three time points (T0 = baseline assessment, prior to intervention; T1 = post-intervention assessment at 6 weeks, immediately after completion of intervention; and T2 = follow-up assessment at 12 weeks after completion of intervention) among road traffic accident victims.
2. To compare the rate of change in the degree of mindfulness between the MBSR group and TAU control group across three time points (T0, T1 and T2 ) among road traffic accident victims.
3. To compare the rate of change in the degree of quality of life between the MBSR group and TAU control group across three time points (T0, T1 and T2 ) among road traffic accident victims.

Methodology :

2.1 Study setting and design This study is a two-armed, parallel group, double blind, randomised controlled trial which is expected to commence on 1st June 2025 to May 2026 for duration of 1 years. The source population is any road traffic accident victims with a diagnosis of PTSD and registered for treatment in Guangdong Jinzheng Judicial Appraisal Center (appraisal qualification: forensic psychiatry).

2.2 Sample size G*Power (version 3.1.9.2) was used to calculate the sample size. A study conducted by Smith et al. (2020) on the effectiveness of mindfulness-based stress reduction in reducing symptoms of post-traumatic stress disorder (PTSD) after road traffic accidents, in which the effect size derived from this study was 0.18. Based on previous studies of mindfulness-based stress reduction therapy (MBSR), we expect a dropout rate of 20% at the end of the study. Taking the dropout rate into account, with a two-tailed alpha error of 5%, a power of 80%, 2 study groups, and 3 measurements. Hence, the estimated sample size needed in this study was 56 participants, 28 in each group (inclusion of 30% drop-out rate).

2.3 Subject recruitment This study will be conducted according to the guidelines of CONSORT. Initially, advertisement in the form of posters will be pasted in the notice board of the targeted centre to explain regarding the study and for subject recruitment. A trained research assistant who is not involved in the study and unaware of the objectives of the study will assist the research team for subject recruitment and randomization. Any road traffic accident victims with PTSD who are interested to participate in the study will be approached by the research assistant. Before formally inviting potential subjects to join the study, members of the research team will provide them with a detailed verbal explanation covering the purpose and procedures of the study. Specifically, potential participants will be clearly explained that their participation in the study is completely voluntary and it is their right to withdraw from the study at any time. At the same time, the research team will take effective measures to ensure that personal information remains anonymous throughout the research process. In addition, important information such as the purpose of the study, the expected benefits and possible risks will be explained to them, as well as the possible use of the data in subsequent research publications. Then, all the potential subjects will be screened for eligibility to participate in the study. The inclusion criteria included: (a) Possession of a road traffic identification certificate issued by the public security traffic police department; (b) Age 18-60 years; (c) junior high school education or above and full civil capacity; (d) those who meet the diagnostic criteria for PTSD according to DSM-5-TR (Diagnostic and Statistical Manual for Mental Disorder 5th Edition-Text Revised) which occurred after road traffic accident; (e) A score of 31 or above on the PTSD Checklist for DSM-5 (PCL-5) indicating possibility of PTSD in diagnosis; and (f) those taking a stable dose of antidepressant for the past 2 weeks and willing to maintain on the dose until the end of the study.

While the exclusion criteria are: (a) Organic brain damage caused by road traffic accident; (b) A previous diagnosis of any mental illness; (c) Pregnant women; (d) Alcohol and drug dependence and abuse; (e) Inability to understand Chinese; (f) history of severe and unstable medical illnesses that are not suitable for participation in the study; (g) having participated in any psychotherapy before participating in the study, and (h) those with suicidal tendency.

Those who fulfil all inclusion criteria without any exclusion criteria will be invited to participate in the study and sign a written informed consent to participate in the study and a copy of the participant information sheet will be given to the participant for their reference and record.

2.4. Randomization: A stratified permuted block randomization according to the stratification of the age (18 to 30 years, 31 to 45 years, and 46 to 60 years) and gender (male and female) will be carried out by the same trained research assistant who assist to recruit sample. A computer-generated random sequential number with specific instruction to assign participant to the allocated group will be given to each participant in an opaque envelope. Participants are randomized into the MBSR and the TAU control groups in a 1:1 ratio.

2.5. Intervention: The intervention in both the MBSR and TAU control groups will be carried out as group therapy in a 60 minutes (with 45 minutes home assignment) once a week session for 6 weeks. Home assignments will be provided at the end of each session. The acceptable number of sessions attended is at least five sessions, whereby those who attended less than that is considered to have insufficient intervention sessions.

2.6. Withdrawal criteria:

Any participants will be allowed to withdraw from the study if:

1. They request for withdrawal
2. They developed serious adverse effects (related or not related to the interventions)
3. They developed deliberate self harm behavior or suicidal tendency

2.7. Blinding: In this study, the researchers will be blinded, as subject recruitment, randomization, and data collection will be conducted by two trained research assistants who are not involved in the study and unaware of its objectives. Additionally, data analysis will be performed by statisticians who are also not involved in the study and followed the pre-planned data and statistical protocols provided. The researchers will only be unblinded after data collection and analysis are completed.

The participants will also be blinded, as they will be randomized to their respective intervention groups according to the allocation sequence concealed in an opaque envelope. All participants received the same duration and level of attention from the same psychotherapist who conducted both the MBSR and TAU intervention sessions. Both intervention sessions will be conducted at the same time of day. Furthermore, participants in the TAU group will be offered MBSR only after the study was completed.

2.8. Data Collection Data collection will be carried out by another trained research assistant who is not involved in this study and does not know about the objectives of the study. Data collection will be performed by face-to-face assessment. All the participants were assessed throughout three time points (T0 = baseline prior to intervention, T1 = 6 weeks after intervention commenced, immediately after completion of intervention, and T2 = 12 weeks after completion of intervention). During T0, all the participants were administered the demographic and clinical characteristics questionnaires, the Chinese versions of the PTSD Checklist for DSM-5 (PCL-5) to assess the severity of the PTSD symptoms (primary outcome), World Health Organization Quality of Life Questionnaire-BREF (WHOQOL-BREF) to measure the degree of quality of life (QOL), and The Five Facet Mindfulness Questionnaire (FFMQ) to evaluate the degree of mindfulness. Then, the PCL-5, WHOQOL-BREF and the FFMQ were re-administered at T1 and T2 to all the participants. In order to reduce attrition rate, phone calls were made to remind participants of their appointment 3 days prior to assessment day and participants who were unable to turn up for assessment face-to-face will be administered the questionnaires through phone call by the research assistant.

3.Statistical analysis 3.1. Descriptive analysis Data analysis will be performed using the social science statistics software (SPSS version 29). Descriptive statistics will be used for the analysis of the socio-demographic data. Gender, age, educational background, marital status, severity of injury, satisfaction with compensation and duration of medication will be described using frequencies and percentages. Inferential analysis will examine significant differences in sociodemographic and clincal characteristics between the experimental and control groups.with Pearson's chi square test and Fisher exact test (if a cell has < 5 subjects).

The method for dealing with any missing data is as follows: if the missing data is less than 5% of the total data collected or is assumed to be completely randomly missing, then it will be deleted using the partial case method. If the missing data exceed 5% of the total collected data but are less than 20%, or are assumed to be randomly missing, multiple imputation will be used to reduce the bias of the missing data on the analysis results. However, if the missing data exceed 20% of the total collected data, multiple imputation will be performed using restricted maximum likelihood estimation, and if the missing data are assumed to be non-random, structural equation modelling (SEM) will be used to process the missing data.

3.2. Mixed linear model: The analysis to achieve objectives (1) to (3) is based on the intention-to-treat analysis, where mixed linear model is use to compute the difference in the rate of change of the primary outcome (total PCL-5 score) and the secondary outcomes (total WHOQOL-BREF and total FFMQ scores) between the MBSR and TAU control groups across the three time points (T0, T1 and T2). The main effect of the interaction between groups (MBSR and TAU) and time (T0, T1 and T2), main effect between group and main effect between time points are computed. Then, the between group post-hoc analysis of the mean difference for each time points and the within group post-hoc analysis of the mean difference across the three time points will be computed for the outcome with a statistically significant main effect of the interaction between group and time. For outcome(s) with significant mean difference between the MBSR and TAU group across time points, the effect size will be computed using Cohen's d.

The effect size is small if d = 0.2, medium if d = 0.5 and large if d = 0.8.

Inclusion Criteria:

(a) Possession of a road traffic identification certificate issued by the public security traffic police department; (b) Age 18-60 years; (c) junior high school education or above and full civil capacity; (d) those who meet the diagnostic criteria for PTSD according to DSM-5-TR (Diagnostic and Statistical Manual for Mental Disorder 5th Edition-Text Revised) which occurred after road traffic accident; (e) A score of 31 or above on the PTSD Checklist for DSM-5 (PCL-5) indicating possibility of PTSD in diagnosis; and (f) those taking a stable dose of a single antidepressant for the past 2 weeks and willing to maintain on the dose until the end of the study.

Exclusion Criteria:

(a) Organic brain damage caused by road traffic accident; (b) A previous diagnosis of any mental illness; (c) Pregnant women; (d) Alcohol and drug dependence and abuse; (e) Inability to understand Chinese; (f) history of severe and unstable medical illnesses that are not suitable for participation in the study; (g) having participated in any psychotherapy before participating in the study, and (h) those with suicidal tendency.

The details of each participants are protected and shall remain its anonymity as requested by the institutional review board.

statisticians that analysed the data