Background
In evaluating musculoskeletal upper-extremity disorders patient-reported measures of disability and pain are now increasingly used as primary outcomes in randomized trials and observational studies [
1]. They are also frequently used in national registries.
The currently available measures that assess outcomes related to the hand and wrist are the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire [
2], the Michigan Hand Outcomes Questionnaire [
3], the Upper Extremity Function Scale [
4], the Boston Carpal Tunnel Syndrome (CTS) Questionnaire [
5], and the Patient-Rated Wrist Evaluation (PRWE). The PRWE is a joint-specific outcome measure that is widely used in evaluating patients with wrist diseases or injuries [
6,
7].
The relative advantage of the PRWE compared to other upper-extremity specific patient-reported outcome measures, such as the DASH, is that the PRWE is wrist-specific and its score is less influenced by possible concomitant shoulder and elbow problems. Besides, it was primarily developed to assess the constructs of pain and disability in patients with distal radius fracture (DRF), the most common facture in the human body [
6]. Reviews have concluded that the PRWE is a reliable, valid and responsive measure of pain and disability in patients with DRF and other hand and wrist conditions [
8,
9].
Studies that have assessed the reliability of the PRWE have reported intraclass correlation coefficient (ICC) values ranging from 0.78 to 0.94 in patients with different wrist/hand injuries suggesting good reliability [
6,
10‐
13]. While the DASH may be more appropriate for patients with disability and pain in multiple areas in the upper extremity, the PRWE has demonstrated superior validity and responsiveness in patients presenting with pain and disablement only in the wrist or hand [
14].
The PRWE has been adapted to many different languages [
10‐
12,
15‐
25]. Several Spanish-language patient-reported outcome measures related to upper-extremity assessment are currently available, including the DASH, QuickDASH, Boston CTS questionnaire, and CTS-6 [
1,
26]. To our knowledge, a Spanish (Spain) version of the PRWE has not been published. The PRWE-Spanish would be a useful patient-reported outcome measure for clinical research in Spain and would facilitate comparison of results from clinical research concerning DRF and other wrist problems.
The aims of this study were: 1) translation and cultural adaptation of PRWE into Spanish (Spain), and 2) preliminary assessment of test-retest reliability, internal-consistency, measurement error, and construct validity in patients with DRF.
Discussion
The results of this study have demonstrated that the Spanish version (Spain) of the PRWE had good internal-consistency and test-retest reliability. The correlations were concordant with the a priori formulated construct hypotheses supporting good construct validity. The results of the adaptation process showed an equivalence in translation scores (ETS) of at least 85% and the difficulty in translation scores (DTS) ranging from 0 to 30. Similar results were reported in the Spanish adaptations of the CTS questionnaire using the same adaptation-translation method (ETS range, 85 to 100; DTS range, 0 to 20), the DASH (ETS range, 98 to 100; DTS range, 5 to 45) [
1], and SF-36 (ETS range, 80 to 100; DTS range, 5 to 45) [
28]. Only one PRWE item had to be modified by converting pounds to kilograms, as was done in other language versions of the PRWE [
19,
24,
25]. The adaptation process used to obtain the Spanish version of the PRWE generally followed the guidelines applied to many previous cross-cultural adaptations of health status and quality-of-life measures [
37].
Internal-consistency analysis demonstrated a Cronbach alpha coefficient greater than 0.7 in subscale items and total items of the Spanish PRWE both at baseline (range 0.96 to 0.98) and at 8 weeks (range 0.89 to 0.95). A similarly high internal consistency has been found in previous cross cultural-adaptations of the PRWE. Cronbach alpha values ranging from 0.89 to 0.92 have been reported for the Hindi version with a sample of 50 patients with DRF with no information about type of treatment [
24], and of 0.93 to 0.95 for the Korean version in 63 patients with DRF treated with open reduction and volar plate fixation [
25]. High internal consistency values for the PRWE have been shown in wrist conditions other than DRF (such as scaphoid fracture, arthritis, carpal ligament injuries, wrist synovial cyst, and other conditions), with Cronbach alpha between 0.81 and 0.98 [
10,
11,
18,
19]. Cronbach alpha value of 0.8 indicates good internal consistency and value of 0.9 indicates excellent internal consistency. Although a very high Cronbach alpha may indicate item redundancy it has the advantage of yielding better cross-sectional precision for scores at the individual level [
29].
Test-retest reliability analysis showed an ICC higher than 0.8 for the 8-week and 9-week responses and for the 12-week and 13-week responses. The 1-week washout time used in this analysis was similar to that used in previous test-retest reliability analyses of the PRWE, which ranged from 2 to 7 days [
7,
10,
19]. The level of test-retest reliability observed for the Spanish (Spain) version total score was similar to that reported for the original version (ICC = 0.90) [
7] and for most of the other language versions, ranging from 0.81 to 0.96 [
10,
11,
19,
24,
25]. In our study, the test-retest reliability was high even in two different stages of the follow-up after DRF, at 8–9 weeks when higher disability is expected, and at 12–13 weeks when the disability is expected to be lower. Thus, the PRWE-Spanish yielded stable scores in the same population on 2 different occasions within a 1-week washout period during which patients were unlikely to experience substantial health changes and thus assumed to be stable [
38]. Consequently, the Spanish PRWE achieved excellent reliability.
The precision of the measurement estimates the error around the observed score, either at one time point (cross-sectional precision) or over time (longitudinal precision). Cross-sectional precision estimates the measurement error based on the Cronbach alpha coefficient. In this study the SEM was 2.67 at baseline and 4.36 at 8 weeks. There is no previous information about SEM of the PRWE based on Cronbach alpha, possibly due to the fact that it is more common to calculate the SEMdiff in measurement [
19,
34,
38]. The SEMdiff for the PRWE total scores in our study was 7.61 and 6.18, the MDC
90 was 11.57 and 10.19, and the MDC
95 was 13.74 and 12.11. These values are lower than the results shown in the study by John et al. [
12] who reported a MDC
95 of 22.5 in a sample of patients who had undergone interposition arthroplasty for thumb carpometacarpal osteoarthritis approximately 6 years earlier. Our results were similar to others described in previous versions of the PRWE. Schmitt and Fabio [
13] found SEMdiff of 5.22 and MDC
90 of 12.2 in a sample of patients with upper extremity musculoskeletal disorders. John et al. [
12] reported SEMdiff of 8.12 for the PRWE total scores (10.54 for pain, and 7.81 for function) in a sample of patients with thumb osteoarthritis. In a sample of patients with DRF Mehta et al. [
24] reported SEMdiff of 5.4 and MDC
90 of 12.5.
Appropriate statistics for assessing measurement error are the limits of agreement (LoA) and the smallest detectable change (SDC) or minimal detectable change (MDC), both directly related to the SEMdiff [
34,
38‐
40]. An important issue when we compare MDC is that this absolute reliability index, called smallest real difference (SRD) [
34] or smallest detectable change (SDC) [
38,
40], depends on several factors including the study population, washout interval, time point during the follow-up when the test-retest analysis was done, and the variance of the data [
34].
MacDermid and Tottenham [
14] demonstrated convergent validity of the original PRWE by showing a strong correlation with the DASH scores (
r = 0.72). We found a similar correlation (
r = 0.71) between the Spanish (Spain) PRWE and the QuickDASH at the baseline measurement. A higher correlation between the DASH and the PRWE was observed in the Swedish version in patients with DRF at 7 weeks (
r = 0.86) [
17], in the Dutch version (
r = 0.84) [
16], and in the Japanese version (
r = 0.81) [
11]. We found higher correlation (
r = 0.79) between PRWE and the QuickDASH at 8 weeks after DRF.
We have found only one study that examined the correlation between the PRWE and QuickDASH; Sandelin et al. [
21], using the Finnish version of the PRWE, observed a strong correlation at 2 and 4 months after DRF. The negative moderate correlation between PRWE Spanish (Spain) and the EQ-5D Index (−0.44 and −0.40), concordant with the pre-specified hypothesis, provides an additional support of the construct validity of the PRWE (higher disability related to wrist disorder correlates with lower quality of Life). To our knowledge no previous study has used the EQ-5D Index in construct validity analysis of the PRWE. However, many authors have used other quality-of-life measures, such as SF-36, in the construct validity hypothesis testing. MacDermid et al. [
6] found a negative moderate correlation between the scores for the PRWE subscales and the SF-36 bodily pain scale ranging from −0.54 to −0.73. John et al. [
12] reported a negative correlation between the PRWE total score and different physical dimensions of the SF-36 (physical functioning −0.46, role physical −0.39, physical component summary −0.54).
Assessment of construct validity should include testing hypotheses that can demonstrate the proposed construct. The two most important factors when choosing the hypotheses are the health dimension or concept measured and the direction of scoring of the measures [
26]. We expected a strong positive correlation between the PRWE and the QuickDASH because both measure a similar concept (disability) and are scored in the same direction (higher score indicates more disability). We hypothesized a moderate negative correlation between the PRWE and the EQ-5D Index because they measure different but related concepts (disability and health related quality of life, respectively) and patients with high wrist-related disability are expected, to some extent, to have lower quality of life. A previous study of patients with CTS used responsiveness analysis to assess construct validity by demonstrating the hypothesis that an upper-extremity specific measure, the DASH, was expected to have lower responsiveness than a disease-specific measure, the CTS symptom severity scale, and higher responsiveness than a generic instrument, the SF-36 [
41]. For the PRWE-Spanish, demonstrating the construct validity hypotheses suggests that it is a valid patient-reported measure of pain and disability related to wrist injury. The PRWE-Spanish would be an important tool that can assist researchers in evaluating outcomes and clinicians to follow patients after DRF. Our study has limitations. The scales assessing translation equivalence and translation difficulty have not been validated previously, although they have been used in similar studies. The sample size is moderate but in accordance with the sample size calculation and accepted standards. We have no data about the number of potentially eligible patients that may not have been asked about participation. Another limitation is the lack of responsiveness analysis. The results presented in this study can be generalizable only to patients with non-operatively treated DRF, because the psychometric properties of an outcome measure are context-specific.
Further studies regarding responsiveness and interpretability including determining the minimal clinically important difference are needed to complete the analysis of the measurements properties of the Spanish (Spain) PRWE. Future research direction for the PRWE Spanish and the PRWE in general should include studying its measurement properties in other wrist disorders.