Kumar 2013.

Methods	RCT, parallel, (fish oil vs nil), 12 months Summary risk of bias: moderate or high
Participants	Patients > 60 years with sinoatrial node disease and dual chamber pacemakers N: 39 intervention, 39 control randomised (18 intervention vs 39 control at 12 months) Level of risk for CVD: moderate/high Male %: 46% intervention, 56% control Mean age in years (SD): 78 (7) intervention, 77(8) control Age range: not reported Smokers: not reported Hypertension: 72% Medications taken by at least 50% of those in the control group: statin, renin‐angiotensin system inhibitors Medications taken by 20%‐49% of those in the control group: anti‐arrhythmic drugs Medications taken by some, but less than 20% of the control group: not reported Location: Australia Ethnicity: not reported
Interventions	Type: omega 3 capsule Comparison: EPA + DHA vs nil Intervention: a triglyceride preparation containing a total of 6 g/day of omega‐3 polyunsaturated fatty acids of which 1.8 g/day were n‐3 (1.02 g EPA and 0.72 g DHA). Dose: 1.8 g/d EPA + DHA Control: no supplements Compliance: measured by weekly dietary history and pill count. Fatty acid status measured at randomisation and between 1‐3 months post randomisation (blood samples). Duration of intervention: median 378 days
Outcomes	Main study outcome: atrial fibrillation burden Dropouts: 1 intervention, 0 control Available outcomes: all cause mortality, CV mortality, AF (frequency and duration but not recurrence so not used), adverse events Response to contact: written but no contact yet
Notes	Study funding: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation was performed using sequentially numbered, opaque, sealed envelopes.
Allocation concealment (selection bias)	Low risk	As above
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open label design
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "At each visit, stored AT/AF diagnostic data were retrieved in an un‐blinded fashion"
Incomplete outcome data (attrition bias) All outcomes	High risk	Only 1 lost, and reason explained. 21 of the 39 randomised to the intervention were crossed over to control at 6 months so 12‐month outcomes are reported for 17/18 intervention while baseline characteristics are reported for the 39 patients.
Selective reporting (reporting bias)	Low risk	Trial prospectively registered and outcomes stated were reported
Attention	Unclear risk	As only the intervention group had supplements there was potential for attention differences. Other contact appears the same.
Compliance	Low risk	EPA was 3‐fold higher and DHA 1.8 fold higher compared with controls. EPA and DHA did not change significantly in controls upon repeat testing
Other bias	High risk	Odd design – 21 of the 39 randomised to the intervention were crossed over to control at 6 months