Chen 2014.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group Adequate power (evidence of power calculation): none mentioned Allocation concealment method: none mentioned Blinding of outcome assessors: none mentioned Check of blinding: none mentioned Duration of study: June 2011 to October 2012 Randomisation method: computerised/even‐odd numbers
Participants	Baseline characteristics Intervention n: 34 Duration of symptoms (mean): 106.94 (SD 115.92) months Age (mean): 50.76 (SD 12.27) years Sex (% woman): 26.5% Marital status currently married (%): 55.9% Educational status: 12.91 (SD 1.68) years Control n: 30 Duration of symptoms (mean): 83.96 (SD 102.32) months Age (mean): 50.70 (SD 11.55) years Sex (% woman): 23.3 % Marital status currently married (%): 56.7% Educational status: 13.30 (SD 2.29) years Overall n: 64 Inclusion criteria: VEEG‐confirmed non‐epileptic events of interest, which were interpreted to be of psychogenic origin based on combined features of ictal semiology, psychosocial history and results from psychological screening instruments. Exclusion criteria: main place of dwelling beyond commutable distance (patients referred from outside VA medical centres); suspected mixed disorder of PNES and epilepsy (people with prior EEG documentation of electrographic seizures or interictal epileptiform abnormalities); and Mini‐Mental Status Examination score of 25, when assessed during the EMU admission. Pretreatment: no statistically significant differences at baseline between groups.
Interventions	Intervention characteristics Intervention Description: group psychoeducation programme (3 × 1.5 hours over 3–5 months) Length of treatment: 3–5 months Longest follow‐up after end of treatment: 3 months Comedications/other treatments while in the study: none. Control Description: TAU with 2 follow‐up appointments with neurologist Length of treatment: 3–5 months Longest follow‐up after end of treatment: 3 months Comedications/other treatments while in the study: none
Outcomes	Level of functioning (WSAS) Outcome type: continuous Data value: endpoint Dropout Outcome type: dichotomous Data value: endpoint Healthcare use – hospital visits Outcome type: dichotomous Data value: endpoint
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "patients were each independently designated a computer generated."
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	16 withdrew in the intervention group and 9 withdrew in the control group. Withdrawal was accounted for.
Selective reporting (reporting bias)	High risk	The background data that are used for describing the PNES frequency were not available even though they were used in the article. The primary outcome was not sufficiently reported. No protocol available.
Other bias	Low risk	No other apparent sources of bias.