Norway‐Denmark 1999.

Methods	G: unknown C: central allocation Patients/doctors/assessors blind Not intention‐to‐treat
Participants	Norway and Denmark 163 randomised 77 to selegiline; 86 to placebo Incl: untreated idiopathic PD or levodopa < 6 months, H&Y I ‐ III Excl: age <35 or >75, dementia, psychosis, unstable diseases Baseline mean UPDRS: selegiline 37; placebo 35
Interventions	Treatment: selegiline 10 mg daily Control: placebo Both groups also received levodopa Duration of treatment: up to 5 years
Outcomes	Deaths UPDRS Mean levodopa dose Motor fluctuations Dyskinesia Withdrawals due to side‐effects Total withdrawals
Notes	Mean FU: selegiline 2.9 yrs; placebo 3.1 yrs 1 month washout
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "randomisation was done centrally by the study monitor in each country" Comment: Probably random
Allocation concealment (selection bias)	Low risk	Quote: "randomisation was done centrally by the study monitor in each country" Comment: Central allocation.
Blinding (performance bias and detection bias) Doctors, All outcomes	Unclear risk	Quote: “Double‐blind” Quote: "Sealed envelopes containing the treatment code were added to the study material. The code was broken by the data analyst after the analyses were done.” Unclear if envelopes were opaque and placebo identical.
Incomplete outcome data (attrition bias) Mortality	Low risk	Rx: 77 randomised, 73 analysed C: 86 randomised, 81 analysed 9 excluded (three protocol violations, six not deemed to have Parkinson’s disease after one year FU). Data not given by randomised group.
Incomplete outcome data (attrition bias) Parkinsonian impairment & disability	Unclear risk	Rx: 77 randomised, 62 analysed (reason for withdrawals unclear) C: 86 randomised, 73 analysed (reasons for withdrawlas unclear)
Incomplete outcome data (attrition bias) Participants requiring levodopa	Low risk	Outcome not assessed
Incomplete outcome data (attrition bias) Motor fluctuations & dyskinesias	High risk	Rx: 77 randomised, 65 analysed (reasons for withdrawal not given) C; 86 randomised, 72 analysed (reasons for withdrawal not given)
Selective reporting (reporting bias)	Unclear risk	No protocol available.
Other bias	Unclear risk	Different mean durations of FU: slightly longer in control arm (2.9 vs 3.1 yrs). Quote: “supported by Orion Pharma”