The substitute question for the Tampa Scale for Kinesiophobia was introduced with the sentence, You visited your general practitioner because of complaints in your back or leg, followed by the question How much ‘fear’ do you have that these complaints would be increased by physical activity? (scores range from 0 = no fear, to 10 = very much fear). Disability: The Roland Morris Disability Questionnaire for sciatica is a validated measurement for disability ( Patrick et al 1995, Roland & Morris 1983). It contains 24 questions that can be answered with ‘yes’ or ‘no’. The substitute question for the

Roland Morris Disability Questionnaire PD0325901 in vitro was, In your normal daily activities, how much trouble do you have from your back or leg complaints? (scores range from 0 = no trouble, to 10 = maximal trouble). Health-related quality of life: The EQ-5D is a validated measurement of health outcome ( Lamers et al 2006, The EuroQol Group 1990). The EQ-5D was developed by the EuroQol group and consists of 5 questions on mobility, self care, usual activities, pain/discomfort, and anxiety/depression, with

3 answer categories. A weighted sum results in a score in the range –0.3 to 1, with higher scores indicating better health status. The SF-36 is a validated questionnaire to survey health status ( Aaronson et al 1998, Ware and Sherbourne 1992). It contains 36 questions, each with 2 to 5 response options. The SF-36 has no overall score, but two summary scores can be calculated: a physical component summary and a mental Obeticholic Acid component summary. Because of a large overlap, we created one substitute question for both the EQ-5D and the SF-36 physical component summary. This substitute question was, How would

you rate your general health? (scores range from 0 = excellent, to 10 = very poor). Outcome measures were global perceived effect and pain severity in the leg at 1 year follow-up. Assessment of the outcome measures was done using a mailed questionnaire to be filled out by each participant. Thalidomide Global perceived effect was measured on a 7-point scale ranging from 1 = completely recovered, to 7 = vastly worsened. Global perceived effect is regarded as a clinically relevant, reliable, and responsive outcome measure (Bombardier 2000, Dworkin et al 2005). We dichotomised the ratings into ‘recovered’ (‘completely recovered’ and ‘much improved’) and ‘not recovered’ (‘slightly improved’ to ‘worse than ever’) (Luijsterburg et al 2008). Pain severity in the leg was scored on an 11-point numerical rating scale ranging from 0 = no pain, to 10 = unbearable pain (Von Korff et al 2000). A numerical rating scale is regarded as a clinically relevant, reliable, valid, and responsive pain scale (Dworkin et al 2005). Missing values in the original trial database were imputed by assigning the last available score. Our research question was answered by calculating correlations and applying logistic regression models.