A pilot study was conducted on 10 patients initially (5 with hip problem and 5 with knee problems), in clinic chosen at random to fill out the questionnaire. Then the patients were asked about their interpretation of each item, language ease, understanding of the concepts and assessed for need of assistance when filling out the questionnaire before launching the full-scale study.
The data was gathered randomly from 110 patients who had undergone a surgical intervention for their knee or hip. The subjects completed the MELLS questionnaire. They gave their written consent to use the information they had provided for the purpose of this study. The average age of the participants was 48.1 years, with standard deviation of 15.07 years; implying that the majority of the sample was between 33 and 63 years of age. The youngest participant was 18, and the oldest was 78 years of age. The female to male ratio 1:1. The patients were given 3 patient related outcome questionnaires adapted for Arabic speakers, including MELLS, WOMAC and OHS.
The Middle East Lower Limb Score (MELLS)
This questionnaire consists of 43 questions, all of which are focused on the problems patients are experiencing with their lower limbs (knee and hip). This questionnaire is primarily an adaptation of WOMAC questionnaire, which is adjusted to specifically address the cultural issues of the middle eastern patients. MELLS uses five point Likert-type scale, where 0 indicates that the respondent is not experiencing any difficulties/pain, and 5 indicates that the patient experiences the highest level of difficulty/pain. Unlike WOMAC, this questionnaire consists of two domains, Pain (25 Items) and Daily activity (18 Items). One score is calculated for each patient by summing the responses to all of the 43 items. Therefore, a score of 172 means that the patient is experiencing severe hip/knee difficulty/pain. In order to standrdize the scores with 0-100 metric system, the following formula is used:
All 110 patients have completed MELLS-questionnaire in at least two different occasions after the surgical intervention (T1 and T2). There was a 2 week interval between the first two times they had filled the questionnairs [4-5].
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)
Arabic version of WOMAC has been already validated in the study conducted by Guermazi M. et al., thus, it was used in this study to investigate the validity of MELLS . There were 24 Likert-type questions here and each patient had scores from three different subscales. First subscale – pain – had 5 questions (score range 5-20), 2 questions addressed stiffness (score range 2-8), and physical function had 17 questions (range 17-68). A minimum score on each of the subscales means that patient essentially did not feel any discomfort in his/her hip (if any), and a higher score suggests greater disability. At the end, the WOMAC scores were rescaled according to 0-100 system. The survey was taken in two different occasions, with a time period of 2 weeks between them.
Oxford - 12 Item Hip Score
Another questionnaire which was used in this study to investigate the validity of MELLS was Oxford Hip Score (OHS). Arabic version of OHS has already been validated by Khaja A. et al. and could be used to examine the validity of MELLS . This questionnaire consists of 12 questions, all of which are focused on the patients' hip problems. To answer these questions, repondents use five point Likert-type scale, where 1 indicates that the respondent is not experiencing any difficulties, while 5 indicates that the patient experiences the highest level of difficulty. One score is calculated for each patient by summing the responses to all of the 12 items. Therefore, a score of 60 means that the patient is experiencing severe hip pain.
Patient Burden and feasibility
We recorded the average time it took each participant to fill out the questionnaire as well as if they required any assistance during the process as part of the patient-burden investigation. The feasibility was determined. It took an average of 6 minutes to complete the questionnaire. There were no difficulties understanding the language of the survey.
Data analysis and psychometric scale properties
All the analyses were conducted using IBM SPSS Statistics v.26 and GraphPad Prism v.8 for the visualization of the results. The test-retest reliability of the questionnaire was examined by using Cronbach’s alpha, and interclass correlation coefficient. The patients completed the questionnaire on two different occassions, so Cronbach’s alpha was calculated for all two situations to determine internal validity.
Convergent and divergent construct validity were tested by using the spearman's correlation coeffiecnts for the 12-items of the oxford hip score and the WOMAC.
Content validity was tested by examining the floor and ceiling effects. Floor effect represents the percentage of patients who had the lowest score (0), and ceiling effect is the percentage of those with the highest (100).
Correlation with WOMAC and OHS subscales were estimated to evaluate convergent validity of the MELLS questionnaire. If it was a valid instrument to measure hip/knee pain, its scores should have positive correlation with all the subscales from the questionnaire.