Goldstein 2010.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group Adequate power (evidence of power calculation): sample size calculation. Based on previous experience, we assumed a true mean change in monthly seizure frequency of 7.3 in the CBT group, no change in the SMC group, and a common SD of 9.5 seizures. Therefore, 28 per group were required to detect a difference with this effect size (Cohen 0.768) with 80% power at P < 0.05. Allowing for a 20% dropout rate, the study authors sought to recruit 35 participants per group; resource limitations resulted in recruitment of 33 per group. Allocation concealment method: developed from a table of random numbers, using unstratified permuted blocks of 4, and concealed in sealed envelopes. The envelopes were then numbered consecutively and given to an independent clinician who allocated them in order as patients gave written informed consent. Blinding of outcome assessors: no information provided Check of blinding: no information provided Duration of study: June 2001 to April 2007 Randomisation method: independently prepared sequence of consecutive, randomised treatment assignments.
Participants	Baseline characteristics Intervention n: 33 Duration of symptoms: 6.3 years (mean 5.9) Age (mean): 37.4 (SD 12.6) years Sex (% woman): 72.73% Ethnicity: 31 white Marital status currently married, n (%): 16 (48.5%) Educational status: 13 unemployed Control Number of participants: 31 Duration of symptoms: 5.1 years (mean 6.8) Age (mean): 35.9 (SD 15.1) years Sex (% woman): 83.87% Ethnicity: 27 white Marital status currently married, n (%): 16 (51.6%) Educational status: 18 unemployed Overall n: 64 Inclusion criteria: aged 18–70 years; clinical diagnosis of PNES primarily confirmed by VEEG telemetry, and only if this was not feasible by ictal EEG, or where the referrer and consultant neuropsychiatrists involved in the study agreed that there was no doubt about the diagnosis and that further investigation was unjustified ('clinical consensus'). Exclusion criteria: coexistent diagnosis (past occurrence) of epilepsy; 2 seizures per month; current drug or alcohol misuse; benzodiazepine use exceeding the equivalent of diazepam 10 mg/day; IQ 70 Pretreatment: similar demographic characteristics and seizure histories at enrolment.
Interventions	Intervention characteristics Intervention Description: CBT. Up to 12 weekly/every 2 weeks for 1‐hour outpatient sessions of CBT with a CBT‐trained nurse therapist with experience in working with people with PNES. Length of treatment: 4 months Longest follow‐up after end of treatment: 6 months Comedications/other treatments while in the study: SMC as received by control Control Description: SMC. Participants were offered ongoing clinic review by a neuropsychiatrist. Appointment frequency was determined by clinical need. Sessions were supportive in nature and provided explanations about the psychological basis of the seizures and supervised withdrawal of AEDs. Length of treatment: 4 months Longest follow‐up after end of treatment: 6 months Comedications/other treatments while in the study: none
Outcomes	Monthly seizure frequency Outcome type: continuous Mental state – anxiety (HADS) Outcome type: continuous Mental state – depression (HADS) Outcome type: continuous Level of functioning (WSAS) Outcome type: continuous Primary health service use (number of GP consultations) Outcome type: continuous Dropout Outcome type: dichotomous
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "patients were randomised to CBT or SMC using an independently prepared sequence of consecutive, randomised treatment assignments. This was developed from a table of random numbers, using unstratified permuted blocks of 4, and concealed in sealed envelopes."
Allocation concealment (selection bias)	Low risk	Quote: "This was developed from a table of random numbers, using unstratified permuted blocks of 4, and concealed in sealed envelopes. The envelopes were then numbered consecutively and given to an independent clinician who allocated them in order as patients gave written informed consent."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: "Therapy sessions were audio‐recorded. Two independent raters evaluated the content of sessions 4 and 9. Overall ratings of therapeutic alliance and CBT were calculated." Comment: no blinding due to the nature of the study, but independent rating of therapy to assure consistency.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropouts accounted for.
Selective reporting (reporting bias)	Low risk	Clinical trials register NCT00688727. The study followed this.
Other bias	Low risk	No other apparent sources of bias.