Table 1 Study characteristics

Golub 1998 [13]

Comparison between LA and OA in adults formally, RCT, published in English

Medline (09/1992 – 07/1997), 16 studies included

Meynaud-Kraemer 1999 [16]

Comparison between LA and OA in adults, RCT, published in English/ French/ German

Medline (search period not reported), 8 studies included

Temple 1999 [19]

Patients with preoperative diagnosis of acute appendicitis comparison between LA and OA, RCT (random allocation of patients into LA or OA), published in English, LA intended to be therapeutic rather than diagnostic, ≥ 80% of randomized patients were followed up for at least one of the main outcomes

Medline (01/1990 - 03/1997), 12 studies included

Bennett 2007 [12]

Comparison between LA and OA for acute appendicitis, RCT, allocation concealment, published in English peer-reviewed journal, not as abstract reported

Cochrane Library, Medline, Embase, (1995 – 05/2006), 33 studies included

Li 2010 [14]

Comparison between LA and OA, RCT, published in English, desirable outcome reported

Medline, Embase, Central (01/1990-12/2009), 44 studies included

Liu 2010 [15]

Comparison between LA and OA, ≥9 years old, not pregnant, no drug abuse, no psychiatric disorder, RCT, no language restriction

Medline, Embase, Cochrane Library (01/1992 – 01/2008), 16 studies included

Sauerland 2010 [18]

Comparison between LA and OA in adults or children with symptoms and signs of acute appendicitis, RCT, adequate concealment of allocations, no language restriction, authors of an abstract were requested for details and had to provide full information on their trial, more than 50% appendix specimens without histological signs of inflammation

Medline, Embase, Cochrane Library, Lilacs, CNKI, SciSearch Cochrane/Medline (- 15/04/2010) remaining databases (-08/2009), 67 studies included

Wei 2011 [20]

Comparison between LA and OA, RCT, published in English, most recent article from the same institution when several studies reporting the same patients, at least four variables of interest could derived from the published results, no variations on the standard laparoscopic technique including laparoscope-assisted or single-trocar appendectomy

Medline, Embase, Current Contents (01/1992 – 02/2010), 25 studies included

Ohtani 2012 [17]

Comparison between LA and OA, RCT, abstracts excluded (only included if full text was published), published in English, at least one of the outcome measures mentioned

Medline, Embase, Central, Science Citation Index (01/1990 – 02/2012), 39 studies included