2.1. Patients and study design
Ethical approval for the study was obtained from the Institutional Review Board at the American University of Beirut, Lebanon. A convenient sample of patients with chronic respiratory insufficiency receiving HMV was identified from clinics specialized in pulmonary medicine across all Lebanon between March 2016 and May 2018. Eligible patients were contacted by their attending physicians who explained the objectives of the study and took their approval to be contacted by the research team. Patients were then approached over the phone for obtaining preliminary consent to participate in the study and were screened for eligibility using the inclusion/exclusion criteria. All patients receiving HMV and clinically stable for more than one month before enrolment were eligible for the study. Patients with a tracheostomy tube, a history of left-sided congestive failure and an exacerbation during the preceding month were not eligible to participate. Consenting eligible patients were visited in their homes for face-to-face interviews. Each interview took around 10 minutes to be completed.
The SRI scale is a multidimensional instrument comprised of 49 items, and seven subscales including: Respiratory Complaints (SRI-RC), Physical Functioning (SRI-PF), Attendant Symptoms and Sleep (SRI-AS), Social Relationships (SRI-SR), Psychologic Well-being (SRI-WB), Anxiety (SRI-AX) and Social Functioning (SRI-SF). The SRI questionnaire assesses the patients’ condition during the preceding one week based on his/her level of agreement rated using a five Likert-scale from “strongly agree” to “strongly disagree”. Typically, subscale scores are generated or a total scale score is generated (SRI-SS) yielding a score ranging between 0 and 100, with higher scores indicating a better quality of life.
Additionally, we administered the SF-36 item scale to measure the general quality of life among our sample. The SF-36 consists of eight subscales measuring diverse components of health status with a score ranging between 0 and 100; with higher scores indicating better health. The eight subscales are the following: SF‐36‐PF = Physical Functioning; SF‐36‐RP = Role Physical; SF‐36‐BP = Bodily Pain; SF‐36‐GH = General Health; SF‐36‐VT = Vitality; SF‐36‐SF = Social Functioning; SF‐36‐RE = Role‐Emotional; SF‐36‐MH = Mental Health .
Sociodemographic and other correlates
Sociodemographic data collected included sex, age, highest educational level, occupation, as well as living arrangements (e.g. who lives with you at home, and who cares for you at home). Additionally, information on smoking behavior for both cigarettes and water-pipe were recorded including current status, age at initiation and quitting (for ex-smokers), and quantity smoked per day, thus allowing the calculation of pack-years. Information about the underlying diagnosis leading to respiratory failure as well as the main indication for the initiation of HMV were assessed. Finally, the patient was asked to specify the time in years s/he have been using the therapy at home and the hours of use during the day.
2.3. Cross Cultural Adaptation
The main purpose behind cross-cultural adaptation is to come up with comparable versions between the original scale (German) and the current version (Arabic). This also includes cultural adaption for each item to ensure reflection at the cultural context.
Stage I: initial translation
The validation procedure started with translating the original Deutsch scale to Arabic.
First, two forward translations into the Arabic language were undertaken by two different professional sworn translators, whose native language was Arabic.
Stage II: synthesis of the translation
Four authors (M.A., L.G., A.S., and M.K.) reviewed and discussed the two translations. It is worth noting that there were no major differences in items between T1 and T2. Minor discrepancies were discussed by the research team who carefully checked any discrepancies between the two translations against the validated English version and a consolidated Arabic version was produced.
Stage III: back translation (BT)
The Arabic version was then back-translated to German by another independent translator, blinded to the original German version, and was compared with the original instrument by a fourth translator. This step was undertaken to ensure correctness of the forward translations. Discrepancies were corrected accordingly, and a pre-final Arabic version was produced.
Stage IV: test of the pre-final version
The version was then piloted and tested among 10 patients with SRI and receiving HMV, identified and recruited in a similar manner through which the study sample was assembled. No amendments were done as the participants highlighted that the Arabic SRI was easy and understandable. The version resulting from the pilot test was used within the data collection tools for the validation study.
Descriptive statistics were generated for the patients’ socio-demographics, disease characteristics, HMV utilization, general quality of life scores, and SRI scores. Principal Components Analysis (PCA) was used to explore the number of underlying factors for SRI scale, and eigenvalues, the scree plot, and the percentage of variance explained were evaluated. The internal consistency of the scale and its subscales were assessed by calculating the Cronbach alpha coefficient. Values of Cronbach’s alpha above 0.7 were considered acceptable . The internal construct validity was assessed using Confirmatory Factor Analysis (CFA) assuming the factor structure as per the original SRI. The model fit was tested through Root Mean Square Error of Approximation (RMSEA) and the Comparative Fit Index (CFI). Values of RMSEA less than or equal to 0.05 indicate a good fit, between 0.05 and 0.08 indicate an adequate fit, and values greater than 0.10 indicate a poor fit. A lower bound of RMSEA 90% confidence interval (CI) less than 0.05, as well as an upper limit less than 0.08, indicate a good fit, whereas a maximum upper bound of 0.10 indicates an acceptable fit. Values of CFI ≥ 0.95 indicate a good fit, values less than 0.95 but greater than 0.90 indicate an adequate fit, and values ≤ 0.90 indicate a poor fit . External nomological validity was finally assessed by evaluating the correlation between the Arabic SRI and the Arabic SF-36. All statistical analyses were done using the Statistical Package for Social Sciences (SPSS) version 23.0.