Pleizier 2017.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group Adequate power (evidence of power calculation): with a sample size of 200 participants (100 per treatment arm), there was 90% power to detect an effect size of d = 0.50, using a 2‐group Student’s t‐test with a 0.05 2‐sided significance level. Allocation concealment method: none. Weakness described that 90% randomised by 1 neurologist. Randomisation in a 1:1 ratio was stratified for type of functional symptoms (pain, 'pseudo' neurological symptoms or 'positive' sensory symptoms) with permuted blocks within the strata. Blinding of outcome assessors: no information provided Check of blinding: no information provided Duration of study: August 2009 to November 2013 Randomisation method: the randomisation procedure was web based (using a validated TENALEA Clinical Trial Data Management System). Randomisation in a 1:1 ratio was stratified for type of functional symptoms (pain, 'pseudo' neurological symptoms or 'positive' sensory symptoms) with permuted blocks within the strata.
Participants	Baseline characteristics Intervention n: 100 Duration of symptoms: 9–12 months Age (mean): 38.90 (SD 14.58) years Sex (% woman): 76% Ethnicity: 76% white Marital status currently living together with partner: 57% Educational status: 46 participants had completed  median term education/higher school (46%) Control n: 95 Duration of symptoms: 9–12 months Age (mean): 40.99 (SD 14.84) years Sex (% woman): 70% Ethnicity: 81% white Marital status currently living together with partner: 55% Educational status: 35 participants had completed  median term education/higher school (37%) Overall n: 195 Inclusion criteria: pain: tension‐type headache (headache without alarming symptoms and not consistent with 1 of the headache syndromes such as migraine, analgesic abuse and cluster headache) and ≥ 1 other FNS; back or neck pain (pain not caused by spinal pathology such as fractures, spondylitis and metastases; myelopathy; radiculopathy; plexopathy or neuropathy) and ≥ 1 other functional symptom; 'pseudo' neurological symptoms: functional movement disorders (movement disorders not consistent with known 'organic' movement disorders); motor impairment other than in movement disorders (motor impairment that cannot be explained by central or peripheral nervous system disorders) or sensory impairment (loss of sensory perception that can neither be explained by central nor by peripheral nervous system disorders), or both; dissociative attacks or PNESs (seizures without evidence for epilepsy on EEGs); 'positive' sensory symptoms: hypersensory perception that can neither be explained by central nor by peripheral nervous system disorders. Exclusion criteria: aged ≤ 18 years; if the duration of the functional symptoms since the first consultation at the GP surgery was > 1 year; known to have psychiatric disorders other than somatoform, depressive or anxiety disorders; primary diagnosis of a severe mood, generalised anxiety or psychotic disorder requiring psychiatric treatment; treated with psychotherapy; known to simulate the symptoms; in dispute about financial or social benefit; experiencing a major somatic disease; and insufficient understanding of the Dutch language. Pretreatment: groups were generally well matched.
Interventions	Intervention characteristics Intervention Description: ≥ 2 follow‐up appointments with neurologist with special training in explaining FNS Length of treatment: about 3 months (12 weeks) Longest follow‐up after end of treatment: about 9 months Comedications/other treatments while in the study: both groups received initial specialised information from neurologist. Intervention could have more follow‐up after another 6 weeks if needed. Control Description: management by GP Length of treatment: about 3 months Longest follow‐up after end of treatment: about 9 months Comedications/other treatments while in the study: no log on what treatments participants may have receive in addition to GP.
Outcomes	Physical symptom load (SF‐36 – Physical Component) Outcome type: continuous Mental state – anxiety (HADS) Outcome type: continuous Mental state – depression (HADS) Outcome type: continuous Dropout Outcome type: dichotomous Data value: endpoint
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The randomisation procedure was web based (using a validated TENALEA Clinical Trial Data Management System). Randomisation in a 1:1 ratio was stratified for type of functional symptoms (pain, ‘pseudo’neurological symptoms or ‘positive’ sensory symptoms) with permuted blocks within the strata."
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: "The GPs were not informed about the randomisation." Participants were not blinded. Personnel unclear.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information (a nurse prompted the participants, but it did not state whether she also scored the replies).
Incomplete outcome data (attrition bias) All outcomes	Low risk	No data available for end of treatment, but as the protocol specified outcome data after 12 months, this was not incomplete.
Selective reporting (reporting bias)	High risk	Protocol was changed shortly before the first submission of the article and outcomes etc were changed. The reported outcomes here match the updated protocol.
Other bias	Low risk	No other apparent sources of bias.