Ellegaard 2019.

Study characteristics
Methods	Double‐blind, randomised, placebo‐controlled trial
Participants	Diagnosis: DSM‐IV bipolar disorder (I, II) on MINI, MADRS score ≥ 18; current acute depressive episode N: 80 Age: N‐acetylcysteine (NAC) group M = 43.7 (SD = 10.0), placebo group M = 43.0 (SD = 10.2) Sex: NAC group = 65% female, placebo group = 52.5% female Baseline depression severity: N‐acetylcysteine (NAC) group MADRS M = 30.1 (SD = 7.9), placebo group M = 28.8 (SD = 7.1)
Interventions	Participants were randomised to receive 20 weeks of treatment with either NAC 3 mg/day or placebo in addition to treatment as usual (medications not specified).
Outcomes	Response Remission Treatment emergent AEs MADRS Bech‐Rafaelsen Melancholia Scale YMRS WHO‐Five Well‐being index Global Assessment of Functioning scale Global Assessment of Symptoms scale CGI‐S
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were quote:“randomly allocated to NAC or placebo add‐on according to a pre‐constructed computer‐generated randomization list divided into blocks of eight.”
Allocation concealment (selection bias)	Low risk	Participants were Quote:“randomly allocated to NAC or placebo add‐on according to a pre‐constructed computer‐generated randomization list divided into blocks of eight.”
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No evidence of blind being tested
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not enough information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	CONSORT diagram included, similar drop‐out rates in both arms.
Selective reporting (reporting bias)	Low risk	Protocol available, outcomes reported as expected.
Other bias	Unclear risk	None identified.