Stefan Elbers

42 Chapter 2 Table 1. Continued. Author (year) cohort N Dropout (%) Lost to follow- up (%) Nationality % Females Mean age ( SD ) Patient group Mean pain duration (months) Verkerk (2011) 1760 3.64 43.1 Netherlands 74.26 40.1 (10.6) Chronic non- specific low back pain 92.4 Volker (2017) 165 6.67 22.08 Netherlands 87 44.1 (12.9) chronic musculoskeletal pain NA Vowles (2011) 187 8.56 36.84 United Kingdom 64.2 47.3 (11.4) chronic pain 96 Wagner (2011) 142 0 0 Canada 63.64 49.16 (10.03) chronic pain 32.99 Westman (2006) 91 NA NA Sweden 70 41.5 (NA) musculoskeletal pain and disability NA Zhuk (2018) 59 NA 85.68 Germany 62.7 45.27 (10.34) low back pain NA