# Arabic translation, cross-cultural adaptation, and validation of the Expectation for Treatment Scale (ETS) in patients with musculoskeletal disorders

## TL;DR

This paper translates and validates the Expectation for Treatment Scale for Arabic-speaking patients with musculoskeletal disorders, ensuring it works well in this cultural context.

## Contribution

The paper provides a culturally adapted and validated Arabic version of the ETS for musculoskeletal patients.

## Key findings

- The Arabic ETS showed good internal consistency (α = 0.75) and high test-retest reliability (ICC = 0.93).
- Low measurement error and acceptable content validity were confirmed for the Arabic ETS.
- Differential item functioning supported the cross-cultural validity of the Arabic ETS.

## Abstract

To translate, culturally adapt the Expectation for Treatment Scale (ETS) into Arabic and evaluate its psychometric properties in patients with musculoskeletal disorders.

Following established guidelines, forward and backward translations were performed, each followed by a synthesis. Face validity of the Arabic ETS was evaluated by asking patients undergoing physiotherapy for musculoskeletal disorders to what extent the ETS items covered their outcome expectations. Internal consistency; test-retest reliability; measurement error; content validity; construct and structural validity, and floor and ceiling effects were assessed.

The ETS was successfully translated and adapted according to the 24 patients’ feedback. 205 individuals completed the online questionnaire, and 36 completed it twice. The Arabic ETS demonstrated good internal consistency (α = 0.75), high test-retest reliability (ICC = 0.93 and κw = 0.75, 0.58, 0.55, 0.66, 0.70, for items one to five, respectively), low measurement error (SEM = 1.42, and SDC = 2.86), and acceptable content validity (0.78). Construct validity was supported (though not definitive) via known-group hypothesis testing (r = −0.331, p < .001) and exploratory factor analysis (χ²(66 = 218.73, p < 0.001). Differential item functioning confirmed the cross-cultural validity. There were minimal floor (0.5%) and ceiling (2%) effects.

The ETS was translated and adapted to Arabic culture. The assessed psychometric properties of the Arabic ETS support its reliable use in patients with musculoskeletal conditions.