Advice

Appendix: Search strategy and evidence selection

Appendix: Search strategy and evidence selection

Search strategy

General background, guidelines and technology assessments

  • Broad internet search: Google: allintitle: omega-3 OR omacor OR maxepa OR PUFA filetype:pdf

  • Trip Database

MEDLINE (via Ovid)

  1. exp Fatty Acids, Omega-3/ (15762)

  2. ((Omega-3 or n-3) adj ("fatty acid$" or "polyunsaturated fatty acid$" or PUFA)).ti,ab. (9839)

  3. ("eicosapentaenoic acid$" or EPA or "ethyl-eicosapentaenoic acid$" or E-EPA or "docosahexanoic acid$" or DHA or "alpha-Linolenic acid$").ti,ab. (18310)

  4. (Omacor or Maxepa or "omega-3-marine triglycerides" or Lovaza or "Krill oil").ti,ab. (280)

  5. 1 or 2 or 3 or 4 (29221)

  6. exp Schizophrenia/ (83135)

  7. schizophreni$.ti,ab. (87663)

  8. 6 or 7 (107440)

  9. 5 and 8 (217)

  10. limit 9 to english language (201)

Embase (via Ovid)

  1. omega-3 fatty acid/ (16332)

  2. ((Omega-3 or n-3) adj ("fatty acid$" or "polyunsaturated fatty acid$" or PUFA)).ti,ab. (9516)

  3. ("eicosapentaenoic acid$" or EPA or "ethyl-eicosapentaenoic acid$" or E-EPA or "docosahexanoic acid$" or DHA or "alpha-Linolenic acid$").ti,ab. (17809)

  4. (Omacor or Maxepa or "omega-3-marine triglycerides" or Lovaza or "Krill oil").ti,ab. (221)

  5. 1 or 2 or 3 or 4 (31561)

  6. exp schizophrenia/ (87593)

  7. schizophreni$.ti,ab. (74762)

  8. 6 or 7 (96299)

  9. 5 and 8 (458)

  10. limit 9 to (english language and exclude medline journals) (52)

Cochrane Central Register of Controlled Trials (CENTRAL)

#1 MeSH descriptor: [Fatty Acids, Omega-3] explode all trees 1704

#2 ("Omega-3" or "n 3") next (fatty next acid*):ti,ab,kw 1318

#3 ("Omega-3" or "n 3") next ("polyunsaturated fatty" or PUFA):ti,ab,kw 548

#4 (eicosapentaenoic next acid*) or EPA or (ethyl-eicosapentaenoic next acid*) or E-EPA or (docosahexanoic next acid*) or DHA or (alpha-Linolenic next acid*):ti,ab,kw 1748

#5 (Omacor or Maxepa or "omega-3-marine triglycerides" or Lovaza or "Krill oil"):ti,ab,kw 87

#6 #1 or #2 or #3 or #4 or #5 2964

#7 MeSH descriptor: [Schizophrenia] explode all trees 4493

#8 schizophreni*:ti,ab,kw 8501

#9 #7 or #8 8501

#10 #6 and #9 31

CRD HTA, DARE and EED database

  1. ("omega-3" or "n 3" or PUFA) OR (eicosapentaenoic or EPA or ethyl-eicosapentaenoic or E-EPA or docosahexanoic or DHA or alpha-Linolenic ) 940

  2. (Omacor or Maxepa or Lovaza or "Krill oil") 2

  3. MeSH DESCRIPTOR Fatty Acids, Omega-3 EXPLODE ALL TREES 0

  4. #1 OR #2 OR #3 940

  5. (schizophreni*) 817

  6. MeSH DESCRIPTOR schizophrenia EXPLODE ALL TREES 428

  7. #5 OR #6 817

  8. #4 AND #7 25

Grey literature and ongoing trials

Manufacturers' websites

Evidence selection

The literature search sought to identify the best available evidence for the use of omega-3 fatty acids for treating schizophrenia. The published literature was searched without restriction on study type. Studies investigating omega-3 fatty acids for preventing schizophrenia in people at high risk were excluded.

In the presence of at least 7 relevant randomised controlled trials (RCTs) and 4 systematic reviews, other study types were excluded. A Cochrane systematic review of RCTs on polyunsaturated fatty acid supplementation for schizophrenia was identified as the best available evidence because it identified the same 7 RCTs that were identified during this literature search, and were included in 4 other recent reviews (Freeman et al. 2006, Ross et al. 2007, Fusar-Poli and Berger 2012 and Politi et al. 2013) identified as most relevant. The Cochrane review was also the most methodologically robust of the reviews identified. In addition, results from the RCT by Manteghiy et al. (2008), which was not included in the Cochrane review because it was published after its search date, were deemed relevant and also included in this evidence summary. Additional safety information from Emsley et al. (2008), was also included, but was not in the Cochrane review. Other sources were used for background information and context.