Thaker 1987.
| Methods | Allocation: randomised ‐ no further information. Blindness: double. Duration: 3 weeks each period. Design: two period cross‐over (preceded by 1‐2 weeks washout). Setting: Inpatients at psychiatric facility, USA | |
| Participants | Diagnosis: schizophrenia (DSM‐III) and antipsychotic induced TD, stable dyskinesia ratings (< 20% variation).
Duration of TD: not reported. N = 9. Sex: 5 male and 4 female. Age: range 22‐36. |
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| Interventions | First study 1. Gamma‐vinyl gamma aminobutyric acid (GVG): dose titrated over 5 days: from 250 mg/d to a maximum dose of 3000 mg/d for three weeks. N = 7. 2. Placebo. N = 7. Free of antipsychotic medication for > 5 weeks. Concomitant medication not reported. Second study 1. THIP: dose increasing over 5 days to 120 mg/day (patient 1); 60 mg/day (patient 2). N = 1. 2. Placebo. N = 1. Antipsychotic free at least 4 weeks prior to study. Concomitant medication not reported. |
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| Outcomes | TD symptoms: SEPS. Mental state: BPRS. Adverse effects. | |
| Notes | No person left study early. THIP produced mental state change and tonic‐clonic seizures 8 days after its withdrawal. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | "The order of drug and placebo periods was randomized", no further details reported. |
| Allocation concealment (selection bias) | Unclear risk | Allocation concealment not reported |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | "patients, staff, and evaluators were blind to the treatment course." Further blinding details not reported. |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | TD symptoms and Mental state: "...evaluators were blind to the treatment course." |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | All participants completed the trial. |
| Selective reporting (reporting bias) | High risk | Not all outcomes have been reported. TD symptoms outcome data reported for the whole population (not per period) in the GVG trial and not reported in the THIP trial. Improvement data not reported for placebo groups. |
| Other bias | Unclear risk | Very small sample size; cross‐over design. Insufficient information to make a judgement |