Appraisal of: Greenhalgh T, Peacock R. Effectiveness and efficiency of search methods in systematic reviews of complex evidence: audit of primary sources. BMJ 2005; 331(7524): 1064-1065.

Short description: 

To describe where papers come from in a systematic review of complex evidence. Only 30% of sources were obtained from the protocol defined at the outset of the study (that is, from the database and hand searches). Fifty one per cent were identified by “snowballing” (such as scanning reference lists (44%) and citation tracking (7%)), and 24% by personal knowledge or personal contacts.

Limitations stated by the author(s): 

No limitations were stated by the authors.

Limitations stated by the reviewer(s): 
The article assesses the total contribution of the different sources but it is not possible to identify the additional references which could only be found by the additional search techniques. Besides that it is not mentioned if perhaps the original Boolean search was inadequate as the searches and the results are not discussed in detail. The generalizability of the results is also questionable because the authors results are based only on one review (topic “diffusion of service-level innovations in healthcare organizations”).
Study Type: 
Single study