Validation of the Spanish Version of the WOMAC Questionnaire for Patients with Hip or Knee Osteoarthritis

Abstract

The aim of this study was to validate a translated version of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire in Spanish patients with hip or knee osteoarthritis (OA). The WOMAC questionnaire and the SF-36 were administered to a sample of 269 patients on the waiting list for hip or knee replacement. We studied the convergent validity and the item-scale correlation using Pearson's correlation coefficient and Spearman's pi. For the reliability study we used another sample of 58 patients who received the WOMAC twice within 15 days. The Pearson's, Spearman's pi, and intraclass correlation coefficients were calculated. Internal consistency was measured by Cronbach's alpha. The responsiveness study was carried out by resending the two questionnaires to all patients 6 months after surgical intervention; responsiveness was measured by means of the paired t-test, the effect size I and the standardised response mean. The Pearson's coefficients for the convergent validity ranged from -0.52 to -0.63. The coefficients obtained for the item-scale correlation of the pain area were 0.74 or higher, 0.91 or higher for stiffness, and 0.61 or higher for function. When measuring the test-retest reliability, the coefficients ranged from 0.66 to 0.81. Internal consistency yielded a Cronbach's alpha ranging from 0.81 to 0.93. The responsiveness showed an effect size I ranging from 1.5 to 2.2 in patients who underwent hip replacement; for those who underwent knee replacement the range was 1 to 1.8. The standardised response mean ranged from 1.3 to 1.9 for patients with hip OA; those with knee OA ranged from 0.8 to 1.5. The Spanish version of WOMAC is a valid, reliable and responsive instrument in patients with hip or knee OA.

The impact of non-traumatic hip and knee disorders on health-related quality of life as measured with the SF-36 or SF-12. A systematic review

“…Spanish reference data for the SF-36 were sex-specific. For the study by Escobar et al [28] we decided to use female reference data from Spain [23], because most patients in this Spanish study were female (TKA 56% and THA 71%).…”

“…Consequently, we refrained from computing pooled z-scores for these studies. We pooled two studies concerning patients with knee or hip OA in clinical settings (data from hip and knee patients were not presented separately in these studies) [29,30], three studies on patients with knee OA in clinical settings [31][32][33], two studies on patients with knee or hip OA, admitted or scheduled for TKA or THA (data from hip and knee patients were also not presented separately in these studies) [34,35], 19 studies on patients with knee OA admitted or scheduled for TKA [25,26,28,33,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] and 23 studies on patients with hip OA admitted or scheduled for THA [26,28,36,[39][40][41][42][43][44][45][46][48][49][50][51][52][53][54][55]…”

“…Of the 40 studies we included, one study concerned patients in the general population [61] (223 patients), three studies concerned community living elderly [27,62,63] (in total 133,358 patients), one study concerned patients in a primary care setting [64] (195 patients), five studies concerned patients in clinical settings [29][30][31][32][33] (in total 1407 patients) and thirty studies concerned patients with OA admitted or scheduled for total arthroplasty (in total 5191 patients admitted for TKA [25,26,28,33,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]65] and 4236 patients admitted for THA [26,28,36,[39][40][41][42][43][44][45][46][48][49][50][51][52][53]…”

Outcomes after total hip replacement based on patients' baseline status: What results can be expected?

“…We used the Likert version of the WOMAC, with 5 responses for each item representing different degrees of intensity that were scored from 0 (none) to 4 (extreme) (8). The WOMAC has been translated into Spanish and validated in Spain (15). For the purpose of this study, we concentrated on the pain and functional limitation domains.…”

Factors and Consequences of Waiting Times for Total Hip Arthroplasty

“…It has a multidimensional scale comprising 24 items grouped into three dimensions: pain (five items), [2,18]. The WOMAC questionnaire was translated and validated in Spain [11]. For the statistical analysis, the unit of study was the patient.…”