Assessment of Psychometric Properties of Life Events Checklist (LEC) in Patients with Chronic Pain

Due to the international pain association, pain is usually defined as sensory and emotional experiences associated with actual or potential tissue damage. Chronic pain: pain with unknown etiology that lasts for more than 6 months after the lesion has healed and leads to emotional distress and increased use of resources in health care systems (1). Studies conducted among the Iranian population indicating that pain is a common phenomenon (2). and also, in some groups of patients, especially patients with experience of trauma and patients with post-traumatic stress disorder (3). The literature indicates that the experience of trauma can be considered as a predisposing factor in many diseases with chronic pain (4).in addition people who experienced trauma were more likely to develop physical, psychosomatic, and psychological disorders. And this issue, in the absence of the necessary precautions, leads to huge financial and psychological costs among the affected population for recovery and treatment (9,10). According to researches, in our country, Iran, less attention has been paid to the experience of trauma in the research. Also, there is no proper tools for screening these patients to use it for early assessment and identification of injured patients. In this regard, the Life Events Checklist (LEC) tool was developed and evaluated in accordance with the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (LEC). The tool consists of 17 items and is designed to assess exposure to potentially traumatic events based on diagnostic criterion A for PTSD in accordance with the DSM-5 (9). Therefore, the researcher had two options to build a new tool or translate existing tools from the original language into Persian and determine its validity and reliability and cultural adaptation to his country and society.

The method of study is a cross-sectional descriptive and validation research. The statistical population of the study consisted of all patients that suffer from chronic pain. The sample size was determined by considering at least 300 participants for studies based on confirmatory factor analysis (15) and also using Krejcie and Morgan chart (16). The sample size was 350 participants. Three chronic pain clinics (chronic pain clinic, chronic pain clinic of Imam Khomeini, chronic pain clinic of Dr. Shariati hospital) were selected in Tehran. Due to the prevalence of COVID-19 to reduce the risk of transmission of the disease, an online questionnaire was designed to send links to the participant's cellphones, and after the necessary explanations, the individuals completed the questionnaires if they were satisfied. Inclusion criteria include age over 18 years, diagnosis of chronic pain by a chronic pain specialist, literacy and exclusion criteria include disagreement with the research conditions and having any physical disability that prevents participation in the study. Data collection was done with a life events checklist that contains 17 phrases which scored on a 6-point scale. To prepare the tool, first, items of the questionnaire was translated into Persian by two master's degree students in psychology. The validity of the content was then assessed by a faculty member in psychology. In the next step, the items were returned to English by a senior English language expert who had not previously read the original version of the questionnaire, and then the original version and the translated version of the questionnaire were reviewed by psychologists to prevent semantic difference in it. After the final version was prepared, the questionnaire was distributed among 36 participants with chronic pain as a pilot and the desired problems in some items were resolved. All participants were given written letter consent including a brief explanation of the objectives, research method, and principle of confidentiality and anonymity. After obtaining consent, participants were asked to complete a package of self-report questionnaires including a life event checklist scale, a chronic pain catastrophe scale, chronic pain self-efficacy, and life satisfaction.Data were analyzed by SPSS software version 25 and LISREL software version 8/8. In order to analyze the data from descriptive statistics (mean, standard deviation, frequency and percentage) as well as Cronbach's alpha method and retest test to examine internal consistency, the correlation of life events checklist scale with DASS-21 questionnaires and chronic pain catastrophe To assess convergent validity and the correlation of this questionnaire with chronic pain self-efficacy and life satisfaction questionnaires was used to assess divergent validity. Confirmatory factor analysis of LISREL version 8/8 was used for construct validity. Exploratory factor analysis was also used to determine the frequency of factors.

The results showed that the phrases had good internal consistency and diagnostic power, except for the seventeenth question, which was excluded from the questionnaire. The correlation of the phrases with the total score varied from 0.27 for phrase 16 to 0.66 for phrase 4 and 14, Cronbach's alpha for the whole scale was equal to 0.86, which indicates the acceptable internal consistency of this instrument. The rate of retesting the questionnaire with a sample of 40 individuals in a period of 3 weeks was equal to 0.85, which is an acceptable score. Also, by considering the KMO value equal to 0/85 and rejecting the null hypothesis in the Bartlett sphericity test (p = 0.000, df = 136, x2 = 1786.27), The results showed that the conditions are ready for factor analysis. Primary analysis indicated four factors. The Scree diagram also supported the four-factor structure. The results related to factor loads show that all expressions have a common variance and a factor load greater than 0.46, in total, the four factors explain 0.56 variance. In the study, RMSEA between 0.8 and 0.10 indicates acceptable model and 0.95 CFI≥ indicates good model fit (27). According to the obtained results and the number of indices after using CFI (comparative fit index) correction indices value 0.95 GFI (goodness of fit index) value 0.90 and (normed fit index) NFI value 0.93 and also index the standardized root error of the mean squares of the RMSEA approximation is 0.7 and the degree of freedom x2 / df is less than 3, all indicating the relative suitability of the model after reformation.

Findings of the study indicated that the Persian version of the scale has an acceptable internal consistency in a sample of chronic pain patients. The findings were consistent with the results of Matt Gray et al., In which Cronbach’s alpha was reported in the study (18). The findings consistent with the study of Halip Bae et al., In whose study Cronbach's alpha was reported 0.66 (12). Another study conducted in South Korea were inconsistent with our findings. In explaining this issue, the concept of culturally oriented trauma can be well justified. In other words, the phenomenon of trauma has a cultural aspect and it is the cultural beliefs of a society that determine the traumatic nature of an event (29, 30). In general, according to the results it can be concluded that the checklist of life events in the Iranian sample with chronic pain is valid and the LEC scale has acceptable psychometric properties. Therefore, therapists and specialists in the field of mental health can use this screening tool in research to diagnose and evaluate trauma in order to prevent or reduce consequences and pathological symptoms.