[German translation and linguistic validation of the modified short questionnaire to assess health-enhancing physical activity (mSQUASH) for patients with axial spondyloarthritis (axSpA)].

Background: Patients with axial spondyloarthritis (axSpA) often experience chronic pain and inflammation, resulting in physical impairments, reduced mobility and decreased physical activity. The modified short questionnaire to assess health-enhancing physical activity (mSQUASH) was developed to assess daily physical activity in patients with axSpA.

Objective: To translate, cross-culturally adapt and linguistically validate the original mSQUASH into German for patients with axSpA.

Methods: The original mSQUASH was translated from Dutch into German using a multistep process (Beaton method) with forward-backward translations into German by bilingual Dutch-German lay people and experts. Any remaining discrepancies were resolved by a scientific committee, resulting in a prefinal German version. Field testing with cognitive debriefing interviews with patients with axSpA from diverse backgrounds led to a final German version.

Results: Minor discrepancies, primarily related to formalities, semantic errors and syntax were found during translations. These were addressed, resulting in slight wording modifications. The prefinal German version was validated through cognitive debriefing by 10 patients with axSpA, confirming its linguistic validity and equivalence to the Dutch version.

Conclusion: Overall, this study confirmed the final German mSQUASH as a comprehensive measurement instrument for daily physical activity. It can now be used as a patient-reported outcome by German patients with axSpA. This can enable cross-linguistic comparisons and expanding its utility across language barriers.