Measurement Properties of the Modified Spinal Function Sort (M-SFS): Is It Reliable and Valid in Workers with Chronic Musculoskeletal Pain?

Abstract

Purpose To analyze the reliability and validity of a picture-based questionnaire, the Modified Spinal Function Sort (M-SFS). Methods Sixty-two injured workers with chronic musculoskeletal disorders (MSD) were recruited from two work rehabilitation centers. Internal consistency was assessed by Cronbach’s alpha. Construct validity was tested based on four a priori hypotheses. Structural validity was measured with principal component analysis (PCA). Test–retest reliability and agreement was evaluated using intraclass correlation coefficient (ICC) and measurement error with the limits of agreement (LoA). Results Total score of the M-SFS was 54.4 (SD 16.4) and 56.1 (16.4) for test and retest, respectively. Item distribution showed no ceiling effects. Cronbach’s alpha was 0.94 and 0.95 for test and retest, respectively. PCA showed the presence of four components explaining a total of 74% of the variance. Item communalities were >0.6 in 17 out of 20 items. ICC was 0.90, LoA was ±12.6/16.2 points. The correlations between the M-SFS were 0.89 with the original SFS, 0.49 with the Pain Disability Index, −0.37 and −0.33 with the Numeric Rating Scale for actual pain, −0.52 for selfreported disability due to chronic low back pain, and 0.50, 0.56–0.59 with three distinct lifting tests. No a priori defined hypothesis for construct validity was rejected. Conclusions The M-SFS allows reliable and valid assessment of perceived self-efficacy for work-related tasks and can be recommended for use in patients with chronic MSD. Further research should investigate the proposed M-SFS score of <56 for its predictive validity for non-return to work.

Multidisciplinary programme for rehabilitation of chronic low back pain – factors predicting successful return to work

“…This also agrees with overseas studies suggesting that a lower job physical demand tends to increase RTW [ 2 , 32 , 33 ]. A better patient-perceived back-specific functional capacity was also noted to have a significant correlation to the ability to RTW, which was supported by current literature [ 2 , 32 , 34 ]. Surprisingly, the status of IOD and its implied associated compensation did not influence the likelihood to RTW as compared to some studies [ 32 , 35 ].…”

Passive Trunk Exoskeleton Acceptability and Effects on Self-efficacy in Employees with Low-Back Pain: A Mixed Method Approach

“…Self-efficacy base scores were relatively high, considering that a self-efficacy score < 56 is hypothesized to be predictive for non-return to work [ 29 ]. However, this was expected, since we recruited participants with low-back pain who still performed in their occupation.…”

“…Although being significant, it can be questioned whether an average change of 5 points in M-SFS score and an increase in self-efficacy by 7% can influence people’s behaviour and increase their confidence in performing work related tasks. According to Trippolini et al [ 29 ], the systematic measurement error for assessing self-efficacy in low-back pain people is around 12–16 points (17–22%). This, however, is only the case for participants having a low self-efficacy (< 60).…”

“…From this scale a total score is calculated, such that high values indicate high self-efficacy (with a max of 80) and low values indicate low self-efficacy (with a min of 0). A M-SFS score < 56 is hypothesized to be predictive for non-return to work in patients with musculoskeletal disorders [ 29 ]. The M-SFS has proven to be of advantage in work-related settings [ 29 ] and is often use to assess the self-perceived functional capacity of patients with back pain.…”

“…A M-SFS score < 56 is hypothesized to be predictive for non-return to work in patients with musculoskeletal disorders [ 29 ]. The M-SFS has proven to be of advantage in work-related settings [ 29 ] and is often use to assess the self-perceived functional capacity of patients with back pain.…”