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Table 3 Risk of bias assessment

From: The impact of omega-3 polyunsaturated fatty acid supplementation on the incidence of cardiovascular events and complications in peripheral arterial disease: a systematic review and meta-analysis

Study Selection bias Performance bias Attrition bias Reporting bias Other sources of bias Overall risk of bias
Random sequence generation Allocation concealment Blinding of participants and personnel Incomplete outcome data Selective reporting
Gans 1990 [37] Low risk Low risk Unclear risk Unclear risk Unclear risk Low risk Unclear risk
Leng 1998 [34] Low risk Low risk Low risk High risk Unclear risk Unclear risk* High risk
Carrero 2005 [35] Low risk Unclear risk Low risk Unclear risk Unclear risk High risk§ High risk
Carrero 2006 [36] Low risk Unclear risk Low risk Unclear risk Unclear risk High risk§ High risk
Ishikawa 2010 [38] Low risk Unclear risk Unclear risk Unclear risk Unclear risk Low risk Unclear risk
  1. *Intervention group received gamma-linolenic acid, which was not supplied in control.
  2. §Intervention group received vitamins B6 and E, folate and oleic acid, which were not supplied in control.
  3. Drop-out rate was > 30%.