Study setting and participants
A total of forty patients with cancer at the Radiotherapy Unit, Oncology Ward, Teaching Hospital, in Southern Sri Lanka were enrolled for the study [31,32,33]. Cancer patients were selected using the appointment register. Inclusion criteria included: having confirmed primary diagnoses as any type of cancer; planning for radiotherapy; able to understand local language Sinhalese and being able to provide informed consent with sufficient physical and mental stability. Subjects with any surgical problems other than cancer-related and in a critical state/end-stage of medical condition were excluded.
Medical officers usually plan radiotherapy for the patients after 14 days of their first visit. The purpose of the study was explained to the selected participants who were on radiotherapy and then written informed consent was obtained. The participation in the study was completely on a voluntary basis.
Baseline characteristics of the cancer patients were obtained using an interviewer-administered questionnaire and the diagnosis cards of the patients. The information gathered were age, gender, marital status, educational and employment status, type of cancer, and time since diagnosis (Additional file 2: Questionnaire). The Centre for Epidemiological Studies-Depression scale (20 item-CES-D)  and the World Health Organization-Quality of Life-BREF scale (26 item-WHOQOL-BREF)  were administered along with the newa S-BC scale among 40 patients with cancer by the principal investigator (PI). Participants were informed to complete the S-BCCES-D, and WHOQOL-BREF which were previously validated in the Sri Lanka. Data were entered into a excel file (Additional file 3: Excel data sheet) without any identification information.
Sinhalese version of the Brief COPE scale (S-BC)—The original BC scale has 28 items and contains 14 subscales with two items on each scale, graded by a four-point Likert scale. The responses to the items were 1 = ‘I have not been doing this at all’, 2 = ‘I have been doing this a little bit, 3 = ‘I have been doing this a medium amount’ and 4 = ‘I have been doing this a lot. A higher score on the subscale items indicates a higher likelihood of using those strategies by the respondents.
As previously mentioned, the BC has two subscale; adaptive coping and maladaptive coping and are shown in the Additional file 1. The first eight subscales (16 items) were adaptive coping strategies, and the other six subscales (12 items) were maladaptive coping strategies . A higher score indicates higher adaptive (score ranges from 16–64) or higher maladaptive coping (score ranges from 12 to 48) practices. Cronbach’s alpha of the original BC was higher than 0.6 for 11 of its 14 subscales. In terms of usage, the BCscale has been widely used in different countries and has been shown good psychometric properties [18,19,20]. In this study a S-BC scale was used to collect data (Additional file 4: English version of S-Brief COPE scale).
The Centre for Epidemiological Studies-Depression scale (CES-D)—The CES-D is a 20-item, short and self-report scale, which was originally developed to assess depressive symptomatology in the general population . Each question has 04 responses from 0 (rarely or none of the time) to 3 (most or all of the time). The total score of the CES-D scale ranges from 0 (no depressive symptoms) to 60 (high level of depressive symptoms). The standard cut-off point that was used to identify those with elevated depressive symptoms was 16 or above. This scale has been validated in Sri Lanka .
The World Health Organization-Quality of Life-BREF scale (WHOQOL-BREF)—The WHOQOL-BREF is a 26-item quality of life (QoL) measurement scale and has four domains: physical, psychological, social, and environmental . Higher values of the total scores indicate a higher level of QoL. The scale has been validated in Sri Lanka .
The BC was used for this study after obtaining permission from the original authors. Cross-cultural adaptation guidelines of Beaten et al.  and the World Health Organization (WHO)  were followed. These included forward translation of the original version, expert panel discussion/synthesis, back-translation, cognitive interviewing, and pre-testing.
First, the forward translation of the original English version of the BC was done. by three independent experts who are fluent in both English and Sinhala language. The PI had independently recorded problems/issues during the forward translation. The multidisciplinary expert panel (including an oncologists, clinical psychologist, clinician, a behavioral scientist and a senior lecture in nursing) discussion was conducted to identify inappropriate statements and necessary changes were incorporated.
Again, three independent bilingual translators (different from the the first group) back translated the Sinhalese version into the English language. They were blind to the original tool. Validity checking was ensured by comparing the back-translated version and the original English version of BC. A preliminary version was developed after reviewing both forward and backward translations. A cognitive interview was performed and focused on each statement to decide whether the wording is unclear, difficult to understand or answer, or to gain suggestions from participants to modify the questions. Some wording modifications were done to make the tool suitable for the Sri Lankan culture. The new scale was circulated among an expert committee to ensure clarity, ambiguity, and understandability of items in the questionnaire.
From the oncology wards, ten patients with cancer were enrolled for pre-testing (those who attended the pre-test were excluded from the main study). Patients were recruited according to the inclusion and exclusion criteria; participants were asked to state whether the items were readable and understandable. A modified version of the BC was found to be a practical tool that can be understood easily the patients with cancer. Finally, the panel of experts has ensured the content validity of the scale. They recommended that the S-BC should be used as an interviewer-administered instrument due to many physical difficulties prevailing in cancer patients (e.g., pain, discomforts) and variations in educational status.
The final Sinhalese version of Brief COPE (S-BC) scale was developed by incorporating face and consensual validity issues expressed by a group of health and research experts (relevance of each item of the scale in assessing coping according to patient’s life and adequacy of the scale to cover all relevant areas of coping were considered).
Several steps were taken to increase the quality of the data gathered because the target participants were cancer patients with various physical and psychological pathologies. Data collection was done by the PI personally. The purpose of the study and nature of the study was adequately explained to all patients and made them aware of the importance of giving true and valid responses in this survey.
Data analysis was done using SPSS 25.0 (IBM statistics, Inc., Chicago). Descriptive statistics were used to illustrate baseline characteristics of cancer patients. The level of significance was taken as 0.05. The internal consistency of the S-BC was examined using Cronbach’s alpha coefficient for the overall scale of the S-BC and for the subscales considering the accepted standard cut-off of 0.60 or above [26, 40].
The internal consistency of the S-BC was examined using Cronbach's alpha coefficient for an overall scale of the S-BC and for subscales. The test–retest reliability was examined using intra-class correlation coefficient (ICC). (The PI administered the same questionnaire among the participants after two weeks of its first administration.). Pearson’s correlation coefficient was used to examine test–retest reliability .
Validity of the S-BC was checked using discriminant, , convergent , and construct validity. Pearson’s correlation coefficient was applied to check the discriminant and convergent validity of the S-BC scale . Convergent validity was assessed by item-subscale correlation considering a higher correlation of each item with their respective subscale. Further, the WHOQOL-BREF and CES-D scales were used to examine convergent and divergent validity. e.
Construct validity of the S-BC was assessed using EFA and CFA. The EFA was performed using Varimax rotation (Kaiser normalization/Kaiser–Meyer–Olkin (KMO)). Bartlett's Test of Sphericity should reach statistically significant result and commonalities coefficients should be high (> 0.6) to fulfil the conditions of this analysis . The number of extracted components was determined by the Scree plot, percentage of variance explained by each component, number of Eigenvalues over one (Kaiser–Guttman rule), and by considering prior psychometric properties of Brief COPE. Items were considered representative of a component if their item loading was ≥ 0.40 and in the cross-loading items, the factor, which had a higher loading value, was taken as the respective factor .
CFA was evaluated using AMOS 23 software . The root means square error of approximation (RMSEA) and comparative fit index (CFI) was examined. The cut-off values for acceptable model fit used for this study were: RMSEA ˃ 0.06 for a good fit; CFI ˃ 0.90 for an acceptable fit .