Belch 1988.
| Methods | RCT, parallel, 2 arms (n‐6 evening primrose oil vs non‐fat paraffin), 12 months Summary risk of bias: moderate to high |
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| Participants | People with rheumatoid arthritis (RA) CVD risk: low Intervention 16 randomised, 16 analysed Control 18 randomised, 18 analysed Mean years in trial: 1 % male: intervention 6%; control 6% Age, years: intervention median 46 years, control 48 years Age range: intervention 35‐68 years, control 30‐74 years Smokers: unclear Hypertension: unclear Medications taken by at least 50% of those in the control group: NSAIDs Medications taken by 20%‐49% of those in the control group: not reported Medications taken by some, but less than 20% of the control group: not reported Location: UK Ethnicity: not reported |
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| Interventions | Type: supplement Comparison: GLA (n‐6) vs non‐fat Intervention aims: 12 capsules of evening primrose oil (Efamol), including 540 mg of gamma linolenic acid (GLA) per day Control aims B: 12 capsules of liquid paraffin per day Dose aim: increase 0.54 g/d GLA, 5 kcal or 0.25% E GLA, assume 70% LA*, 4.2 g/d or 37.8 kcal/d or 1.9% E LA, 2.2% E n‐6 Baseline n‐6: unclear Compliance by biomarkers: no serum total cholesterol or blood markers reported Compliance by dietary intake: unclear, not reported
Duration of intervention: 1 year |
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| Outcomes | Main study outcome: RA activity and NSAID dose Dropouts: intervention 0, control 0 Available outcomes: ESR, CRP, functional status, RA status, NSAID use (authors stated that no deaths or CVD events occurred during the trial) |
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| Notes | Study funding: Action Research for the Crippled Child, and Efamol Ltd provided the supplements Response to contact: Dr Belch contacted and provided some additional information, stating that no deaths or CVD events occurred |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "randomized double blind fashion", no detail provided |
| Allocation concealment (selection bias) | Unclear risk | As above, randomisation method not described. |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Quote: "All three types of capsules were supplied by Efamol Ltd and were visually identical. The capsules were issued to the patients in a randomized double blind fashion". Participants and personnel were probably blinded. |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Not stated |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Quote: "Table 2 shows the number of patients withdrawn from the study by 12 months. One patient in the EPO group and two in the EPO/fish oil group were withdrawn owing to increasing symptoms of RA, compared with 10/18 of the placebo patients (both P < 0.001, Mann‐Whitney). The results from all patients who were withdrawn were analyzed throughout the study on an intention to treat basis". |
| Selective reporting (reporting bias) | Unclear risk | No trial protocol or trials registry entry located |
| Attention Bias | Low risk | Appeared appropriate. Quote: "All participants in all groups needed to attend the clinic at monthly intervals for the first six months and thereafter at 3 monthly intervals." |
| Compliance | Unclear risk | No serum lipid, serum fatty acid or dietary intake data provided |
| Other bias | Low risk | None noted |