Schweizer 1993.

Methods	Study design: Randomised controlled trial
Participants	Diagnosis: DSM ‐ III panic disorder Method of diagnosis: Structured Clinical Interview for DSM‐III, Upjohn Version Age: M = 33, SD = 7 Sex: female = 75%, male = 25% Location: USA; setting: in and outpatients Co‐morbidities: none Rescue medication: Quote: "no concomitant centrally active medication therapy was permitted during the study"
Interventions	Participants were randomly assigned to either: (1) alprazolam arm (n = 37) Duration: 8 weeks short term, 32 weeks long term Treatment Protocol: flexible dosage, range = 2 ‐ 10 mg, M = 5.4, SD = 2.1 (2) imipramine arm (n = 34) Duration: 8 weeks short term, 32 weeks long term Treatment Protocol: flexible dosage, range = 50 ‐ 250 mg, M = 152, SD = 65 (3) placebo arm (n = 35) Duration: 8 weeks short term, 32 weeks long term
Outcomes	Time points for assessment: weekly until week 6, week 8, monthly for 6 months Outcomes: 1. panic attack frequency and severity 2. Hamilton Rating Scale for Anxiety (HAMA) 3. phobias 4. disability resulting from the phobic anxiety 5. global assessment of improvement 6. safety questionnaire (SAFTEE) 7. benzodiazepines plasma levels
Notes	Date of study: not stated Funding source: sponsored by Upjohn Co. Declarations of interest among the primary researchers: not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomized".
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "patients were dispensed identical capsules containing either 1 mg of alprazolam or 25 mg of imipramine".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "patients were dispensed identical capsules containing either 1 mg of alprazolam or 25 mg of imipramine".
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "ITT endpoint analysis, including all patients with at least one week of treatment and 'evaluable patients' or 'decreasing N' analysis, using only those patients available at each visit, were the primary set of analysis conducted. Supplementary completers analysis using only patients who completed either 8 weeks or 32 weeks of treatment were also conducted". "While the high attrition rate in the imipramine and placebo treatment groups posed a problem for the statystical analysis of the various outcome measures, attrition rates themselves constituted an important and independent outcome measures. Survival analysis was performed for on‐study treatment".
Selective reporting (reporting bias)	Low risk	All relevant outcomes were reported.
Other bias	High risk	Sponsored by Upjohn Co; the role of the funder in planning, conducting and writing the study is not discussed.