SCIMO 1999.
| Methods | Study on prevention of Coronary atherosclerosis with Marine Omega 3 fatty acids (SCIMO) RCT, parallel (omega 3 vs average European fats), 2 years Summary risk of bias: low |
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| Participants | People with angiographically proven coronary artery disease N: 112 intervention, 111 control (analysed 82 intervention, 80 control) Level of risk for CVD: high Men: 82% intervention, 78.6% control Mean age in years (SD): 57.8 (9.7) intervention, 58.9 (8.1) control Age range: unclear (18‐75 inclusion criteria) Smokers: 16.2% intervention, 22.3% control Hypertension: 53.1% intervention, 45.5% control (history of high blood pressure) Medications taken by at least 50% of those in the control group: platelet inhibitors, beta‐blockers Medications taken by 20%‐49% of those in the control group: long‐term nitrate therapy, lipid‐lowering agents, ACE inhibitors, diuretics, calcium antagonists, other antihypertensive agents and digitalis. Medications taken by some, but less than 20% of the control group: nitrates only on demand Location: Germany Ethnicity: not reported |
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| Interventions | Type: supplement (capsule) Comparison: EPA + DHA vs SFA + MUFA (average European fat composition) Intervention: concentrated fish oil capsules, 6x 1 g capsules/d for first 3 months, 3 × 1 g/d for rest of study (4 g/d EPA +DHA + DPA + ALA for first 3 months, then 2 g/d). Dose: ˜2 g/d LCn3 Control: capsules containing fat which replicated the fat composition of the average European diet, 6/d for first 3 months, 3/d for rest of study, opaque soft gelatin capsules identical to fish capsules in identical screw‐top containers Compliance: capsule count, overall 2284 (SD 313) capsules taken of 2460 prescribed for each person, erythrocyte phospholipids rose from 4.6% to 11.8% at 24 months in intervention, and didn't alter from baseline in controls Length of intervention: 24 months |
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| Outcomes | Main study outcome: changes in stenosis on angiography Dropouts: unclear Available outcomes: mortality, MI, CV events, revascularisation, angina, stroke, cancer diagnosis, weight, lipids, BP, side effects Response to contact: yes |
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| Notes | Asked participants to guess treatment allocation, of those in intervention 63/90 were unsure, 5/90 guessed placebo and 22/90 guessed fish oil; of those in control 66/85 were unsure, 9/85 guessed placebo and 10/85 guessed fish oil Study funding: Pronova provided capsules and funds for study monitoring but it was stated that the funders played no part in analysis or publication |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Stratified, and for the resulting 9 strata "a random sequence of study group assignments was computer generated by the trial monitor" |
| Allocation concealment (selection bias) | Low risk | Sealed, sequential numbered envelopes used (opaque not stated, but provided only a random number which linked to a specific container of capsules). |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Placebo and fish oil capsules "looked identical and were made of soft opaque gelatin and each contained 1 g of a fatty acid mixture". These were provided in identical containers with identical labels with a randomisation number. Patients were told that capsules differed in composition but not in taste. |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Blinding is described and is very strong for angiographic outcomes, but there is no description of how cardiovascular events were assessed or recorded. However outcomes assessors were probably the same assessors and so blinded |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | Unclear for how many participants clinical events were assessed (though described in detail for angiographic outcomes), so trial flow unclear |
| Selective reporting (reporting bias) | Unclear risk | No study trials register entry or protocol was found |
| Attention | Low risk | As study personnel were unaware of assignments bias in attention was not possible |
| Compliance | Low risk | Capsule count, overall 2284 (SD 313) capsules taken of 2460 prescribed for each person, erythrocyte phospholipids rose from 4.6% to 11.8% at 24 months in intervention and didn't alter from baseline in controls |
| Other bias | Low risk | No further bias noted |