Lerner 2001.

Methods	Allocation: Randomised Blinding: Double Duration: 9 weeks Setting: Inpatients in Be'er Sheva Mental Health Centre, Israel. Design: Cross‐over study, divided into two phases of 4 weeks each, with 1 week wash‐out period.
Participants	Diagnosis: Schizophrenia or schizoaffective disorder. N = 15. Age: 28 ‐ 71 years. Sex: 4M,11F. History: Mean chlorpromazine equivalent of 490 mg/day. Included were patients who fulfilled diagnostic criteria for tardive dyskinesia; stable on antipsychotic medication for at least one month; Excluded were patients on vitamin treatment, concurrent medical/neurological disorder and those with substance or alcohol abuse.
Interventions	1. Vitamin B6, increased by 100 mg/week from 100 mg/day to 400 mg/day in twice daily divided doses (n = 8). 2. Placebo (n = 7).
Outcomes	Global: Clinical efficacy: reduction in ESRS scores from baseline by 4 weeks Adverse effects other than tardive dyskinesia ‐ by 4 weeks Average time to discontinuation of P5P: in days ‐ by 4 weeks Average endpoint dose of P5P: in mg ‐ by 4 weeks Deterioration in tardive dyskinesia symptoms: ESRS ‐ by 4 weeks Average endpoint tardive dyskinesia scores: ESRS ‐ by 4 weeks
Notes	The authors did not mention the specific diagnostic instrument used in confirming the diagnoses of participants included in the trial.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised, no further details were provided.
Allocation concealment (selection bias)	Unclear risk	Not described by authors.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	"The study design was double blind, with crossover and placebo control." No further details were provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	"The raters were kept blind to the results". The specific method by which blinding was achieved was not described.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No attrition among participants was reported.
Selective reporting (reporting bias)	High risk	Not all outcomes were accounted for e.g. the specific number of participants who showed none, minimal, moderate or marked improvement in their tardive dyskinesia symptoms from both arms of the study were not reported.
Other bias	Unclear risk	The authors did not give details as to what extent raters in the study were independent. It was not mentioned if any funding was received for the study. The specific diagnostic criteria used for inclusion of participants in the study was not mentioned.