The Brazilian Portuguese version of the Exercise Adherence Rating Scale (EARS-Br) showed acceptable reliability, validity and responsiveness in chronic low back pain

Abstract

Background: This study aimed to adapt the Exercise Adherence Rating Scale (EARS) into Brazilian Portuguese and evaluate its measurement properties, given as reliability, validity, and responsiveness in patients with non-specific Chronic Low Back Pain (CLBP).

Methods: A total of 108 patients with a mean age of 46.62 years (SD = 9.98) and CLBP participated in this longitudinal study. Participants were oriented on undertaking the prescribed exercises in the first session, and adherence behavior was assessed after 1 week, and finally reassessed after 2 weeks (test-retest reliability). Three weeks after the first assessment, they were invited again to full fill the EARS (responsiveness). The intraclass correlation coefficient (ICC_2,1) and Cronbach's α were used to assess test-retest reliability and internal consistency, respectively. Spearman's correlation and confirmatory factor analysis (CFA) were used to assess construct validity, and the Receiver operating characteristic curve and area under the curve (AUC) were used to analyze responsiveness.

Results: The one-factor EARS-Br (adherence behavior) structure with 6 items showed acceptable fit indexes (comparative fit index and goodness of fit index> 0.90 and root-mean-square error of approximation< 0.08). The EARS-Br scale showed acceptable internal consistency (α = 0.88) and excellent reliability (ICC = 0.91 [95% CI 0.86-0.94]). Mild to moderate correlations were observed between EARS-Br total score vs. disability, pain catastrophizing, depression/anxiety, fear-avoidance and pain intensity. A Minimally Important Change (MIC) of 5.5 in the EARS-Br total score was considered as a meaningful change in the adherence behavior (AUC = 0.82). Moderate accuracy (AUC = 0.89) was obtained for a 17/24 total EARS cutoff score after home exercise was prescribed. The sensitivity and specificity were also acceptable (greater than 80%).

Conclusion: Our results demonstrated acceptable EARS-Br reliability, validity, and responsiveness for patients with CLBP. A final score of 17/24 on EARS after the prescription of home-exercise could be used as a cut-off for an acceptable adherence behavior associated with improvement in patient outcomes.

Keywords: Adherence; Chronic low Back pain; Prescribed exercise; Responsiveness; Validity studies.

Fig. 1

Flowchart of the process of cross-cultural adaptation to Brazilian Portuguese of the Exercise Adherence Rating Scale (EARS) in five stages: I) initial translation into Brazilian Portuguese – original version in British English was translated into Portuguese by two translators fluent in English and native speakers of Portuguese - a layman and an expert in health sciences, who worked independently; II) synthesis of translations – both translations were synthesized through consensus; III) back-translation into the original language – two translators fluent in Portuguese and native English speakers back-translated the synthetized version into English. They worked independently and both were blinded to the original version; IV) specialist committee – meeting with translators (n = 4), physiotherapists (n = 6) and PhDs and researchers with expertise in exercise (n = 4) to solve possible disagreements in translation, and create a pre-final version of EARS-Br and V) pre-testing phase – in which the pre-final version of the questionnaire was administered to patients with CLBP (n = 25) and assessed regarding comprehensibility of the instrument controlled through an open field form and cognitive interviews. Participants were encouraged to report their possible doubts, impressions of each item, response options, header items, instructions, and instrument layout

Fig. 2

Flowchart showing sample distribution through EARS-Br validation study phases

Figs. 3A and 3B

Path diagram showing factor structure of the EARS-Br (Fig. A) and EARS-Br reasons for adherence (Fig. B) describing the factor loadings for each item. Q = questions. e = error. EARSbehavior = EARS. EARSreasons = EARS reasons for adherence or EARS-RA

Fig. 4

Receiver Operating Curves (ROC) describing sensitivity and specificity values for responsiveness analysis of the Brazilian version of the Exercise Adherence Rating Scale (EARS-Br). A: Minimally Important Change for EARS-Br considering as reference Global Perceived Effect (GPE), comparing EARS score longitudinally. B. Cut-off score for EARS-Br for the final assessment after the exercise program considering as reference Global Perceived Effect (GPE)