Lerner 2007.

Methods	Allocation: Randomised Blinding: Double Setting: Inpatients at Be'er Sheva Mental Health centre, Israel. Duration: 26 weeks Design: Cross‐over study, divided into two phases of 12 weeks each with 2 weeks wash‐out period.
Participants	Diagnosis: All participants met DSM‐IV criteria for Schizophrenia (n = 34) or Schizoaffective disorder (n =16). N = 50 Age: Mean ± SD = 47 ± 11 years, Range = 20 ‐ 66 years Sex: 28 Males, 22 Females History: Diagnosis of tardive dyskinesia; exposure to neuroleptics; stable psychotropic regimen for at least 1 month; duration of symptoms of at least 1 year; mean antipsychotic dose = 396.7 ± 280.4 mg/day in Chlorpromazine equivalents. Excluded: Concurrent medical/neurologic illness; pregnant/lactating mothers; patients on any vitamin supplements; substance/alcohol abuse.
Interventions	1. Vitamin B6 (n = 28), 600 mg twice daily (Total ‐ 1200 mg/day) 2. Placebo (n = 22), two tablets twice daily
Outcomes	Clinical efficacy: ESRS ‐ reduction in ESRS score by 12 weeks Adverse effects other than tardive dyskinesia Average endpoint dose of P5P: in mg ‐ by 12 weeks Average time to discontinuation of P5P: in days ‐ by 12 weeks. Deterioration in tardive dyskinesia symptoms: ESRS ‐ by 12 weeks Average endpoint tardive dyskinesia score: ESRS ‐ by 12 weeks.
Notes	The study was supported by a clinical trials grant from the Stanley Medical Research Institute, Bethesda, Md.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised, no further descriptions.
Allocation concealment (selection bias)	Unclear risk	Specific method of allocation concealment not described. " After breaking the code following database lock......"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double blind, no further details was provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	"The plasma levels of Vitamin B6 were not reported to the raters, in order to keep them 'blind' to the patients' drug assignment." The specific method by which blinding was achieved was not described. The extent to which the raters were independent was not mentioned by the authors.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants randomised at the beginning of the study were accounted for.
Selective reporting (reporting bias)	Low risk	There is no evidence of selective reporting in the study.
Other bias	Low risk	Funded by Stanley Medical Research Institute.