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Outcome measure, Knee, Osteoarthritis, Persian, Validity and reliability, What&,rsquo s Known Patient-reported outcome measures allow therapists to evaluate the effects of management from patients&,rsquo vantage point. Knee outcome survey (KOS) is a widely used scale to measure the consequences of knee osteoarthritis. It is designed to evaluate the functional status following a knee injury. What&,rsquo s New The Persian version of the knee outcome survey activities of daily living (KOS-ADL) scale is a valid and reliable measure to assess the functional limitation experienced by patients with different severity of knee osteoarthritis. IntroductionOsteoarthritis (OA) is a type of joint disease characterized by pain and stiffness. It can cause physical disability and eventually become a socio-economic burden on the societies. 1,- 4, OA is the most common chronic and progressive disease in the United States. 1,, 2, Considering the important role of the knee in the lower extremity, knee OA can adversely affect individual&,rsquo s functional independence. 2,, 5, Due to the rapidly increasing prevalence of OA, there is a need for an accurate assessment tool of patients&,rsquo health requirements. 2,, 3, There are several approaches to assess people with OA, among which patient-reported outcome measures (PROMs) are the preferred methods. 6,- 8, The knee outcome survey (KOS) is a widely used scale to measure the consequences of knee OA. 9,- 14, The scale is designed to evaluate the functional status of patients following a knee injury. 12, It includes two separate domains, namely symptoms and activities of daily living (ADL) disturbance related to knee for measurement of symptoms and functional restriction in the activities of daily living (ADL) as well as sport activities. 9, , 13,, 15, The main advantage of this scale is that it differentiates between ADL and sports activity. It can also be used to assess different knee problems such as ligamentous and meniscus injuries, OA, and patellofemoral pain syndrome. 10,, 13,, 16, The KOS scale was originally developed in the English language, 12, then, it has been translated into several other languages such as German, 15, Turkish, 11, Portuguese, 16, and Greek. 13, Considering cultural, lingual, and geographical variations, 17, the validity and reliability of any questionnaire could be negatively affected by the translation process. 18, Hence, the objective of the present study was to assess the validity and reliability, and cross-cultural adaptation of the Persian version of the knee outcome survey-activities of daily living (KOS-ADL) scale.Patients and MethodsThe present cross-sectional and psychometric study was conducted from summer 2015 to fall 2016 at the Musculoskeletal Research Center, Isfahan University of Medical Sciences, Isfahan, Iran. The study was approved by the Ethics Committee of Isfahan University of Medical Sciences (code, IR.MUI.REC.1394.394596). Permission from Professor J.J. Irrgang (the developer of KOS) was obtained to translate the questionnaire into the Persian language. A team of experts together with Professor J.J. Irrgang jointly supervised the process and were consulted for planning and data analysis of the study.The convenient sampling method was used to recruit the participants among patients from various public and private health care centers in Isfahan, Iran. The target population was the patients with varying severity of knee OA, stratified in accordance with the criteria proposed by the American College of Rheumatology (ACR)19 and based on the Kellgren-Lawrence (K&,ndash L) grading scale and the Osteoarthritis Research Society International (OARSI) grading system. 20, Knee radiographs were performed by standing on both legs. 3,, 21, Radiographs taken within two months prior to the study were also accepted to avoid unnecessary exposure of the participants to X-rays. The inclusion criteria were the ability to walk without assistive devices, a pain level of at least 30% on the visual analog scale (VAS), 16,, 22, and proficiency in the Persian language. The exclusion criteria were undergoing physical therapy or other palliative or medical management program that may affect the pain level and ADL within 30 days prior to the study, 23, positive history of other osteo-arthropathies, 23, suffering from heart disease or neurological problems, 24, or any other disabling factor that reduces functional independence and the level of activity, 20,, 25, fracture of the lower extremities within six months prior to the study, 22, steroid injection in any lower extremity joints within six months prior to the study, lower extremity malalignment, 23, severe non-osteoarthritic knee effusion or arthroplasty, 11,, 22,, 23, and other joints pathologies including ligament, menisci, or patellofemoral problems. 12,, 14, A physical therapist, who was blind to the study design, approved the participation of the volunteers by verifying the inclusion and exclusion criteria through a comprehensive physical examination and review of their medical history. Written informed consent was obtained from all the participants. Instruments Knee Injury and Osteoarthritis Outcome Score (KOOS)Considering wrong ordering of the answer options in the LK 1.0 version of Persian KOOS, LK 2.0 was used in the present study. 26, This questionnaire was used to validate the KOS-ADL scale. It assesses the outcomes of five subclasses, namely pain (7 items), symptoms (9 items), ADL (17 items), sport and recreation function (5 items), and knee-related quality of life (4 items). Each item is scored on a Likert scale from 0 (no problems) to 4 (extreme problem). For each subclass, the score is normalized to a 0-100 scale where higher scores indicate better functional status. 27, The Persian version of the questionnaire was developed by Salavati and others. 24, Knee Outcome Survey Activities of Daily Living (KOS-ADL) ScaleThis self-administered scale consists of two domains, namely symptoms (six factors) and ADL disturbance related to knee (eight factors). Note that three additional factors (15 to 17) are not used for calculating the total score of the KOS-ADL scale. The response to the symptoms questions is scored from 0 (the symptom prevents me from all daily activities) to 5 (I do not have the symptom). The response to questions in the ADL disturbance related to knee is scored from 0 (I am unable to do the activity) to 5 (activity is not difficult). The total score is calculated by summing the scores of all 14 factors. 12, Tegner Scale of Physical ActivityTegner is a scale of sports activities. The responses are scaled from level 0 (sick leave or disability pension due to knee problems) to level 10 (competitive sports such as football, soccer, rugby). 28, Negahban and others have cross-culturally adapted the Persian version of the scale. 29, Translation of KOS-ADL ScaleTranslation and cultural adaptation of the scale were in accordance with the protocol recommended by the Manufacturers Alliance for Productivity and Innovation (MAPI). 30, The process included translation into Persian and back translation followed by face validity and reliability assessments. The instrument was translated into the Persian language by two independent native Persian-speaking health professionals with proficient English language skills. The translators were blind to the study design and to the other one&,rsquo s translation. The translated documents were then consolidated by a knee specialist who was blind to the original questionnaire. This preliminary version of the document was reviewed in an expert consensus that included the principal researcher, translators, and three knee specialists. To ensure conceptual equivalence, the final Persian version of the document was independently back-translated into the English language by two separate new translators, who were blind to the original English version of the questionnaire. They were Persian speaking medical specialists who were living in an English speaking country and were blind to each other&,rsquo s translation. Their work was consolidated into one document by a third translator who was blind to the study design and the original version of the questionnaire. This version was subsequently sent to the developer of KOS for confirmation. Initial face validity assessment indicated that eight factors of the second domain of the scale, i.e., ADL disturbance related to knee were unclear to 56.7% of the sample population. Following internal meetings and consultation with the developer of KOS, it was decided to complement those factors requiring further clarification (items 7-14) with simple icons. The subsequent face validity assessment showed that all factors and the associated answers were clear to the sample population.Data CollectionThe participants were selected in accordance with the inclusion and exclusion criteria and studied X-rays, and subsequently, demographic and clinical data were collected through interviews and medical history taking. In line with a previous study, 13, the KOS-ADL questionnaire was initially presented to 30 of the volunteers. In case of any ambiguities, the research team clarified each item of the questionnaire while noting the shortcomings of the translated version. Potential modifications were implemented after consultation with the developer of KOS to conclude the face validity phase. In the validity phase, the modified version of the translated KOS-ADL questionnaire and the Persian version of KOOS were presented to 130 patients. The group was requested to fill in the questionnaire independently, without any guidance from the research team. In the reliability phase, the test-retest method was used. From the recruited patients, 40 patients were requested to fill in the questionnaires again with an 8-day interval. 12,, 24,, 26, Statistical MethodsData were analyzed with SPSS software (version 18.0) using a two-tailed test. P values&,lt 0.05 were considered statistically significant. Content validity was determined using the participants&,rsquo ranking of their knee performance and by the consensus of an expert team (Delphi techniques). 31, The internal consistency of the questionnaire and its domains was evaluated with Cronbach&,rsquo s alpha, and values &,ge 0.70 were considered acceptable. 11,, 13,, 32, To evaluate construct validity, concurrent construct validity was examined with a correlation matrix using the Pearson&,rsquo s correlations coefficient between the domains of KOS-ADL and subclasses of KOOS. 11, Correlation coefficients &,gt 0.50 were classified as strong, 0.35-0.50 as moderate, and &,lt 0.35 as weak. 25, The reliability (test-retest) was examined using the intraclass correlation coefficient (ICC), 10,, 11,, 13,, 15,, 16, where values &,ge 0.7 were considered acceptable. 15,, 33, Descriptive statistics were presented as mean&,plusmn standard deviation (SD) or frequency and percentages. The Kappa coefficient was used to determine the intra-rater agreement, where a coefficient &,le 1 indicated a perfect agreement. 34, Floor and ceiling effects were calculated based on the scores obtained by the participants for each KOS-ADL item. Since in KOS-ADL, the option that shows better knee condition gets higher score in Likert scale, the percentage of selecting the lowest (score 0) and the highest (score 5) indicated the ceiling and floor effects, respectively. If more than 15% of participants scored an item &,ldquo zero&,rdquo or &,ldquo five&,rdquo , then ceiling or floor effects (respectively) was present. 35, The component matrix was extracted using factor analysis. The rotated component matrix was calculated using varimax with Kaiser normalization. ResultsFrom a total of 130 subjects (14 man and 116 woman) who were included in the study, 40 subjects were engaged for test-retest reliability. There were no missing data for any of the items of the KOS-ADL, KOOS, and Tegner scales. However, some demographic data from 31 participants were not available. There was no significant difference between the demographic characteristics of the participants in the validity (n=130) and reliability (n=40) phases (table 1,).VariablesParametersValidity phaseReliability phaseP valueAnthropometric Data (mean&,plusmn SD)Age (years)56.65&,plusmn 9.9457.80&,plusmn 9.280.61Weight (kg)74.04&,plusmn 10.7571.15&,plusmn 10.050.81Height (cm)160.86&,plusmn 8.23159.27&,plusmn 8.710.61BMI (kg/m2)28.70&,plusmn 3.8728.07&,plusmn 3.480.12Sex (n, %)Man14 (10.80)3 (7.50)0.73Woman116 (89.20)37 (92.50)OA severity (n, %)119 (14.60)4 (10.00)0.05269 (53.10)24 (60.00)337 (28.50)11 (27.50)45 (3.80)1 (2.50)Tegner score (n, %)020 (15.40)3 (7.50)0.22127 (20.80)6 (15.00)258 (44.60)24 (60.00)319 (14.60)3 (7.50)42 (1.50)1 (2.50)54 (3.10)3 (7.50)Educational level (n, %)Under diploma51 (39.20)16 (40.00)0.27Diploma25 (19.20)10 (25.00)Post diploma22 (16.90)14 (35.00)Not available32 (24.60)0 (0.00)Symmetrical involvement (n, %)Asymmetrical46 (35.40)7 (17.50)0.02Symmetrical53 (40.80)33 (82.50)Not available31 (23.80)0 (0.00)Present symptoms (n, %)Pain82 (63.10)29 (72.50)0.54Morning stiffness61 (46.90)13 (32.50)0.05Inability to move54 (41.50)15 (37.50)0.39Disturbance in ADL46 (35.40)15 (37.50)0.71Inability to go up/down stairs84 (64.60)29 (72.50)0.28Not available31 (23.80)4 (10.00)0.75BMI, Body Mass Index, OA, Osteoarthritis |