Translation and validation of the Greek version of the Somatic Symptom Scale-8 (SSS-8) in patients with chronic low back pain

Abstract

Purpose

To translate and validate the Greek version of the Somatic Symptom Scale-8 (SSS-8) in patients with chronic low back pain (CLBP).

Materials and methods

The Greek SSS-8, created through forth and back translation and cultural adaption processes, was handed over to 145 patients recruited using simple random sampling. Test–retest, composite, and internal consistency reliability were assessed. Construct validity was examined by assessing correlations with Patient Health Questionnaire-15 (PHQ-15), Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and EuroQoL 5-dimension 5-level (EQ-5D-5L) instruments. Structural validity was assessed using confirmatory factor analysis (CFA). Convergent, discriminant, and known group validity were also evaluated.

Results

The response rate was 95.1% (138 subjects, mean age 43.2 ± 11.7) and the overall Cronbach’s alpha was 0.831. Test–retest reliability assessment revealed excellent results (Pearson's r > 0.996; Lin’s concordance coefficient > 0.995; intraclass correlation coefficient >0.995, all p < 0.001). Composite reliability scores for the pain, cardiopulmonary, and fatigue domains were 0.712, 0.787, and 0.567, respectively. The correlation analyses indicated good construct validity. CFA revealed excellent fit results and known group validity output indicated a linear increasing trend in the severity of somatic symptom disorders (SSDs), depression, and anxiety with higher PHQ-15, PHQ-9, and GAD-7 scores (Jonckheere-Terpstra test, p value < 0.001).

Conclusions

The Greek SSS-8 was shown to be a reliable and valid tool for measuring SSDs in patients with CLBP.

Implications for Rehabilitation

• According to the Global Burden of Diseases Study 2017, LBP was one of the leading causes of disability for both sexes combined since 1990.

• Strategies to identify SSDs in patients with LBP at an earlier stage are essential both for the provision of an optimal targeted treatment and for minimizing its direct and indirect economic burden.

• The Greek SSS-8 is a standardized and validated instrument, which its utilization will enhance the physical therapy assessment process in the Greek population.

• Not only is the SSS-8 an easy-to-use and highly accurate diagnostic tool for detecting SSDs, but also a short alternative to PHQ-15 in settings with limited assessment time.

Keywords:

• Chronic low back pain
• Greek version
• reliability
• somatic symptom disorders
• SSS-8
• validity

Disclosure statement

No potential competing interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.