Translation, reliability, and validity of the German version of the Activity Patterns Scale (APS) in musculoskeletal pain: a methodological study

In musculoskeletal pain (MSP), pain duration, disability, and mental health relate to how a person engages in daily activities. The self-reporting questionnaire Activity Patterns Scale (APS) assesses these activity patterns and their subscales: Pacing (Pacing to increase activity levels,Pacing to conserve energy for valued activities,Pacing to reduce pain); Avoidance (Pain avoidance,Activity avoidance); Pacing (Excessive persistence, Task-contingent persistence, Pain-contingent persistence). This investigation translated the APS into German and estimated its internal consistency, test-retest reliability, and construct validity. The APS translation was conducted following international guidelines for the transcultural adaptation of self-reported measures. For the construct validity, the Avoidance Endurance Fast-Screening (AE-FS), Tampa Scale of Kinesiophobia (TSK), and Coping Strategies Questionnaires (CSQ) scales were employed. Sixty-five participants with MSP contributed to a baseline survey with a follow-up at two weeks. The German version of the APS subscales demonstrated good internal consistency (Cronbach's alpha = 0.670-0.89) and satisfactory test-retest reliability (intraclass correlation coefficient = 0.72-0.82); only Task-contingent persistence revealed a poor result. Construct validity was supported by significant correlations between APS subscales (pacing, avoidance, persistence) with related measures, including the Coping Strategies Questionnaire (0.27 to 0.40; -0.50 to 0.55; 0.27 to 0.50), the Tampa Scale for Kinesiophobia (0.28 to 0.47; 0.36 to 0.37; 0.38), and Avoidance-Endurance Fast Screening Pain Persistence Scale (none; none; 0.40). The findings demonstrate high construct validity by the substantial correlations in the predicted directions for the APS subscales and their corresponding questionnaires. The German version of the APS is a reliable and valid tool for assessing activity pattern subscales in individuals with MSP. This distinction could refine research and customize treatment instructions to regulate people's activity in clinical practice.