MD. MSc., Department of Orthopedics and Traumatology, Fundación Valle del Lili, Cali, Colombia.
MD. Clinical Research Center, Fundación Valle del Lili, Cali, Colombia.
MD. Clinical Research Center, Fundación Valle del Lili, Cali, Colombia.
BSc. Clinical Research Center, Fundación Valle del Lili, Cali, Colombia.
Sociology Student, Harvard University, Boston, USA.
MD. Department of Orthopedics and Traumatology , Fundación Valle del Lili, Cali, Colombia.
Rotator cuff disease (RCD) is a common pathology with a strong negative impact on patient’s quality of life. There are several tools that measure burden of disease attributable to RCD, both prior and after treatment interventions. The Western Ontario Rotator Cuff (WORC) Index, developed in 2003, is an example of a tool that offers a good, reliable and valid way of measuring quality of life in patients with rotator cuff pathology. The intraclass correlation coefficient (ICC) for the original WORC index was excellent (0.96) (
The WORC index has been successfully translated into several languages. Success was defined by high values (close to 1) of internal consistency and reproducibility scores, calculated through Chronbach´s α (CA) and interclass correlation coefficient (ICC). Some examples of CA and ICC for translations are as follows: the Dutch version obtained 0.97 and 0.94, respectively (
Given that RCD is a worldwide pathology, affecting also sufferers from Spanish speaking countries, it is important to have a tool such as the WORC index in Spanish, capable of assessing quality of life and measuring the burden of disease. However, many of the items in the questionnaire would get lost in translation if a mere conversion from English to Spanish of the index was created. The aim of this study is to translate and validate the Spanish version of the WORC score in Colombian population, with cultural adaptation of the index.
Permission for translation and cultural adaptation was
requested to the original WORC index authors. Once permission was granted, two different
healthcare professionals, whose first language is Spanish (a general practitioner
and an orthopedic surgeon), did two independent forward translations, following
the guidelines found in medical research literature (
A total of 60 Spanish-speaking patients from Fundación Valle del Lili (Cali, Colombia), with rotator cuff pathology (tendinitis, partial tear or complete tear) were included in the study. Inclusion criteria were: age older than 18 years plus confirmed diagnosis of RCD by clinical history, physical examination and magnetic resonance evaluation. Only illiterate patients were excluded. Patients were recruited between December 2012 and December 2013 by two orthopedic surgeons who identified eligible patients from the outpatient clinic. The ethics and biomedical investigation committee of Fundación Valle de Lili approved the study prior to its initiation.
Sixty patients were asked to complete the Spanish version of the WORC index. Within a 14-days period, they were asked to complete the WORC index for a second time, with the purpose of carrying out the reliability test.
The WORC index is a self-assessment instrument that has
been used to evaluate quality of life in patients with RCD. It consists of 21 items
distributed in 5 domains: 6 questions of physical symptoms; 4 questions of sports
and recreation; 4 questions of work; 4 questions for lifestyle and 3 questions about
emotions. Each item is answered on a 100 mm visual analogue
scale (VAS). The highest or most symptomatic score is 2100 and the best or asymptomatic
is 0, which implies no reduction in quality of life (
The Stata version 12.0 was used for the statistical analysis.
Demographic and clinical characteristics of the study population were included.
Means, rates, ranges and proportions were calculated for these variables (
54 / 14.8 / 20-88
32 (53.3)28 (46.6)
23 (38.3)37 (61.7)
11 (18.3)23 (38.3)26 (43.3)
1191.3 / 560.7 / 89.5-2100295.8 / 149.9 / 20-600237.2 / 117.1 / 16.5-400249.8 / 122.8 / 16-400234.9 / 118.5 / 5-400173.3 / 102.4 / 5-300
Reproducibility refers to the way in which repeated measurements give similar values. It is measured in terms of the internal consistency and reliability of the instrument. Cronbach’s α (CA) measures the internal consistency of the instrument. It was used for the WORC index’s total score and for each domain. It ranges from 0 to 1, and a value of 0.7 or more indicates adequate internal consistency.
The test-retest reliability is calculated with the intraclass correlation coefficient (ICC). Values range from 0 to 1, and values above 0.80 are considered to have excellent reliability.
The Bland-Altman plot is used to evaluate possible systematic variations in the difference between measurements. It also allows identifying outlier values not recognized by the correlation analysis. The reliable change index (RCI) was also calculated as an indication of the measurement error. RCI is calculated by the formula: 1.96 × Ö2 × SD, where SD is the square root of the variance.
A total of sixty patients (28 men, 32 women), mean age of 54 years (20-88), fulfilled the inclusion criteria and were included in the analysis. Table 1 shows the baseline characteristics of the study population and the mean values of the total WORC score and for the 5 domains.
The internal consistency of the Spanish version of WORC
index measured through Cronbach’s α was 0.96 for the total score, range 0.85-0.94
for the five domains, indicative of a high internal consistency. Excellent test-retest
reliability was seen through an ICC of 0.98, range 0.91-0.97 for the five domains
(
WORC Total Score
0.97
0.99
0.98-0.99
7.6
Physical symptoms
0.85
0.93
0.85-0.96
…
Sports and recreation
0.86
0.92
0.86-0.96
…
Work
0.91
0.96
0.91-0.91
…
Lifestyle
0.86
0.97
0.93-0.98
…
Emotions
0.94
0.91
0.82-0.96
…
The Bland-Altman plot showed no systematic differences
between the first and the second measurement for the Spanish WORC index total score
(
Rotator cuff disease is the most common cause of shoulder pain. It affects negatively the patient’s quality of life, both in the work environment and daily activities. The original WORC index score is a practical and reliable tool for measuring the negative impact of RCD on patient’s lives. Thus a need to translate it into Spanish was imperative. Translation was completed using a systemic standardized approach.
Internal consistency was measured through Cronbach’s α, which yielded a value of 0.96 for the total WORC index score. This is comparable to results obtained in other versions of the WORC index and in the original English version (
High intraclass correlation coefficients representing good test-retest reliability were obtained in this study (
The Bland-Altman plot does not show systematic differences or biases between the first and second measurements of the WORC index, showing adequate internal validity for the measurements. The repeatability coefficient measured with a 7.6% reliable change index, shows no statistically significant difference between the first and second set of measurements.
The study limitations were given by the lack of comparison with other scales used for the same purpose, such as the Shoulder Pain and Disability Index, RC-QOL or the Oxford Shoulder Score. Such comparison would help to know which one is the most reliable and consistent of these tools. Though, this comparison was not possible because there were no published Spanish versions available for those scales when this study was conducted.
The time span between measurements in the same individuals was between 0-14 days with a mean interval of 2 days; this short interval might relate with the similarity of response and the higher value obtained for the ICC. Nevertheless, longer periods of interval could show differences related to the treatment that patients are receiving and affect negatively the score’s reliability.
The Spanish version of the WORC index is a reliable, consistent and valid instrument for evaluating quality of life in patients with rotator cuff disease in Spanish speaking countries such as Colombia.