Hubschmid 2015.

Study characteristics
Methods	Study design: randomised controlled trial Study grouping: parallel group Adequate power (evidence of power calculation): no information provided Allocation concealment method: randomisation to IPI or SC was done through 24 identical, non‐transparent, sealed envelopes, half containing a paper stipulating 'treatment' and the other half 'standard'. Blinding of outcome assessors: no, to minimise dropout of participants Check of blinding: no blinding Duration of study: November 2010 to January 2013 Randomisation method: randomisation to IPI or SC using 24 identical, non‐transparent, sealed envelopes, half containing a paper stipulating 'treatment' and the other half 'standard.' Envelopes were independently prepared and sealed, and given to a third person unaware of the content to mix. They were numbered consecutively and given in chronological order to patients as written informed consent was signed.
Participants	Baseline characteristics Intervention n: 11 Age (mean): 37.57 (SD 4) years Sex (% woman): 60% Control n: 12 Age (mean): 31.53 (SD 3.17) years Sex (% woman): 90.91% Overall n: 23 Inclusion criteria: aged 16–65 years; newly diagnosed conversion disorder according to the (DSM‐IV‐TR) (within 12 months) with motor or NEA symptoms assessed by experienced neurologists. Exclusion criteria: lack of verbal fluency in French; neurological comorbidity with motor or gait symptoms, or concomitant epilepsy diagnosed by an experienced epileptologist; psychiatric comorbidity of psychosis, acute suicidality or current substance abuse; or current psychotherapy at the time of inclusion. Pretreatment: no statistically significant differences at baseline between groups.
Interventions	Intervention characteristics Intervention Description: 4–6 sessions of brief psychotherapeutic intervention, with extended and joint neurologist/psychiatric meeting at first and last session. Therapy was based on a psychodynamic interpersonal treatment approach. Length of treatment: 2 months Longest follow‐up after end of treatment: 10 months Comedications/other treatments while in the study: none Control Description: SC. Consisted of the diagnosis established by both neurologist and psychiatrist, then the SC group received a single joint neurological and psychiatric diagnosis restitution of about 15 minutes. The participant was informed using the terminology of 'functional neurological disorder' and advised to seek psychiatric–psychotherapeutic treatment with a psychiatrist in private practice. The GP was also informed. Neither further psychotherapeutic intervention nor systematic neurological follow‐up was offered. Length of treatment: 2 months Longest follow‐up after end of treatment: 10 months Comedications/other treatments while in the study: none
Outcomes	Conversions symptoms (SDQ‐20) Outcome type: dichotomous Quality of life (SF‐36) Outcome type: continuous Use of health service emergency department Outcome type: continuous Mental state – depression (BDI‐II), Outcome type: dichotomous Dropout Outcome type: dichotomous
Notes	The use of health services at 4 and 10 months' follow‐up were not included in this review, as data did not allow for inclusion in the analysis.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization to IPI or SC was done through 24 identical, nontransparent, sealed envelopes, half containing a paper stipulating "treatment" and the other half “standard." The envelopes were independently prepared by H.M. and sealed, and then given to a third person unaware of their content to mix. They were numbered consecutively and given in chronological order to patients as written informed consent was signed."
Allocation concealment (selection bias)	Low risk	Quote: "Randomization to IPI or SC was done through 24 identical, nontransparent, sealed envelopes, half containing a paper stipulating "treatment” and the other half "standard." The envelopes were independently prepared by H.M. and sealed, and then given to a third person unaware of their content to mix. They were numbered consecutively and given in chronological order to patients as written informed consent was signed."
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No blinding of personnel delivering the intervention to keep participants throughout the study. So the authors had actively made a decision. Nothing mentioned for participants.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "This trial was not blinded, as part of the measures was rated by the therapists themselves, to try and limit the dropout rate. Other measures were self‐administered."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropouts accounted for.
Selective reporting (reporting bias)	Low risk	No changes to trial outcomes were made after trial started. The following outcome measures were analysed as per protocol.
Other bias	Low risk	No other apparent sources of bias.