Table 2.

Outcome measures

Primary outcome
Pain intensity	• Numerical rating scale (NRS), ranging from 0 ‘no pain’ to 10 ‘worst pain imaginable’ [55].
Secondary outcomes
Pain dimensions	• Pain duration (number of painful days in the last 4 weeks).
	• Pain Experience Scale (SES) measures the affective and sensory dimensions of pain [56].
Medication	• Change in medication intake.
Disability	• 12-Item Short Form Health Survey (SF-12) measures health-related quality of life [57,58].
Depression and Anxiety	• Hospital Anxiety and Depression Scale (HADS-D)[59].
Stress/ Trauma	• Change in Posttraumatic Diagnostic Scale levels (PDS)[60].
	• Dissociation symptoms questionnaire (DES/FDS-20) for assessment of dissociative symptoms [61].
Somatization	• Somatization scores of the SCL-90R subscale somatization (SCL-90R) [62].
Somato-sensory function	• Quantitative Sensory Testing (QST) for assessment of all relevant aspects of the somatosensory system including large and small fiber function as well as signs of central sensitization (dynamic tactile allodynia, punctate mechanical hyperalgesia) [63].
Conditioned pain modulation	• Conditioned Pain Modulation (CPM) paradigm for assessment of inhibitory pain modulating mechanisms [64]. Difference in pressure pain threshold before and after inducing CPM by a phasic heat pain stimulus will be measured.