Job requirements and physical demands (JRPD) questionnaire: cross-cultural adaptation and psychometric evaluation in Iranian Army personnel with chronic low back pain

Abstract

Background: Biomechanical risk factors have been identified as the main predisposing factor of chronic low back pain (CLBP), especially in Army personnel. The Job Requirements and Physical Demands (JRPD) questionnaire has been developed to assess the biomechanical exposures related to CLBP. Examining the biomechanical risk factors could prevent CLBP. This study aimed to translate and cross-culturally adapt the JRPD into Persian and assess its psychometric properties among Iranian male Army personnel with CLBP.

Methods: In this cross-sectional study, the content validation of the JRPD was assessed after translating to Persian. The Persian JRPD was administered to 198 male Army personnel with CLBP, with an interval of 7 days, to assess test-retest reliability, including Cronbach's α, intraclass correlation coefficients (ICC), standard error of measurement (SEM), and minimal detectable change at 95% confidence interval (MDC_95%). Scores of the Persian JRPD were correlated with the scores of visual analog scale (VAS), Borg's category-ratio (CR10) scale, general health questionnaire-28 (GHQ-28), and physical functioning (PF₁ and PF₂) subscale of the 12-item short-form health survey (SF-12) to assess convergent validity using Spearman correlation for a priori hypotheses.

Results: The Persian JRPD had good content validity evidenced by the higher content validity index (> 0.70). The questionnaire had a significant positive negligible to weak correlation with the VAS (rho = 0.27; p < 0.001), Borg's CR10 scale (rho = 0.19; p = 0.009), and the total score of GHQ-28 and its domains (rho ≤0.34; p < 0.05); and significant negative weak correlation with PF₂ (rho = - 0.27; p < 0.001) and significant negative moderate correlation with PF₁ (rho = - 0.35; p < 0.001), thus confirming the priori hypotheses (89%, 8/9). The internal consistency and ICC (α = 0.91; ICC = 0.80) were highly adequate, with SEM and MDC_95% of 7.91 and 21.3 respectively.

Conclusions: The JRPD was successfully adapted into Persian and had adequate psychometric properties in terms of content and convergent validity, internal consistency, and test-retest reliability. The questionnaire is found useable to assess the CLBP-related biomechanical exposures in Iranian male Army personnel.

Keywords: Army personnel; Cross-cultural adaptation; Low back pain; Persian; Psychometric properties; Validity and reliability.