Zitman 1991.

Methods	Double‐blind, placebo‐controlled cross‐over trial study
Participants	34 patients, mean age 34 years Inclusion criteria: pain duration at least 6 months, age between 30 and 60 years Exclusion criteria: severe psychiatric disease, renal, hepatic or cardiac disorders, epilepsy, glaucoma, hypertension, prostate dysfunction
Interventions	Baseline (2 weeks) 75 mg amitriptyline and 3 mg flupentixol; first treatment (5 weeks) 75 mg amitriptyline and 3 mg flupentixol (scheme A) or 75 mg amitriptyline alone (scheme B); washout period (2 weeks) both groups placebo; 2nd treatment (5 weeks) crossing‐over from scheme A to B and vice versa
Outcomes	Zung depression scale, Hamilton depression scale, clinical screening for extrapyramidal side effects, Abnormal Involuntary Movement Scale (AIMS), pain intensities (numeric scale 0 = no pain, 10 = unbearable pain) No differences between the amitriptyline group and the amitriptyline + flupentixol group concerning the pain
Notes	Type of pain: somatoform pain disorder; 2 refused to participate, 9 dropped out during treatment
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Described as "identical placebo tablets"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Described as "identical placebo tablets"
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Imputation method not described
Size	High risk	Fewer than 50 patients/treatment arm

i.v. ‐ intravenous