Secondary outcome measures
disability, pain
To measure health-related quality of life, the Short Form 36 (SF-36) and the EuroQol 5 Dimensions 3 Level Questionnaire (EQ-5D-3L) were used. SF-36 is a widely used generic health status questionnaire, consisting of 36 questions organized into eight multi-item scales: physical functioning, role limitations due to physical problems, bodily pain, general mental health, social functioning, role limitations due to emotional problems, vitality, and general health perceptions. Each raw scale score is transformed into a linear 0–100 scale. A higher score represents less disability. The German- and Dutch-language versions are proven practical, reliable, and valid among general and chronically diseased populations [To assess functional status objectively, the Timed Up & Go Test (TUG) and the Five Times Sit-to-Stand Test (FTSST) were conducted. The TUG is considered a practical and reliable test to assess physical mobility [