Table 1.

Characteristics of included studies

First author, study year [reference]	Number of patients	Age (years)	Gender n	Appendicitis prevalence (%)	Country	Setting	Study type	Patient population
Abdeldaim 2007 [19]	242	Median 42 Range 8 to 76	Male 90 Female 152	51	Ireland	Emergency department	Retrospective	Right iliac fossa pain
Al Qahtani 2004 [8]	211	Mean 32 Range 13 to 70	Male 125 Female 86	57	Saudi Arabia	Emergency department	Prospective	Suspected acute appendicitis
Alvarado 1986 [5]	277	Mean 25.3 Range 4 to 80	Male 131 Female 96	82	USA	Hospital inpatients	Prospective	Abdominal pain
Arain 2001 [20]	100	Mean 19.9	Males 44 Females 56	48	Pakistan	Surgical unit	Prospective	Suspected acute appendicitis
Baidya 2007 [44]	231	Mean 26.3 Range 16 to 65	Male 141 Female 90	52	India	Emergency department	Prospective	Right iliac fossa pain
Bond 1990 [21]	187	Range 0 to 18		61	USA	Emergency department	Prospective	Abdominal pain
Borges 2003 [22]	76	Age 2 to 6 = 23 Age 7 to 10 = 38 Age > 10 = 15	Male 40 Female 36	71	Brazil	Emergency department	Prospective	Suspected acute appendicitis
Canavosso 2008 [23]	224	Mean 26.65 Range 13 to 82	Male 117 Female 10	84	Argentina	Emergency department	Prospective	Right lower quadrant pain
Chan 2001 [25]	148	Mean 29 Range 10 to 73	Male 107 Female 41	34	Singapore	Emergency department	Retrospective	Suspected acute appendicitis
Chan 2003 [24]	175	Mean 30 Range 8 to 73	Male 130 Female 45	43	Singapore	Emergency department	Prospective	Right iliac fossa pain
Denizbasi 2003 [45]	221	Mean 26.6	Male 112 Female 109	79	Turkey	Emergency department	Prospective	Abdominal pain and suspected acute appendicitis
Escriba 2011 [42]	99	Mean 11.2 Range 4 to 17.8	Male 62 Female 37	42	Spain	Emergency department	Prospective	Abdominal pain/suspected appendicitis
Farahnak 2007 [26]	21	-	-	48	Iran	Emergency department	Prospective	Abdominal pain
Gwynn 2001 [27]	215	-	-	66	USA	Emergency department	Retrospective	Abdominal pain
Hsiao 2005 [28]	222	Mean 9.4 Range 1 to 13	Male 146 Female 76	50	Taiwan	Emergency department	Retrospective	Suspected acute appendicitis
Kang 1989 [46]	62	Mean 45.8 Range 18 to 78	Male 42 Female	68	China	Hospital inpatients	Prospective	Suspected acute appendicitis
Khan 2005 [29]	100	Mean 20.2 Range 9 to 56	Female 59 Male 41	54	Pakistan	Surgical ward	Prospective	Suspected acute appendicitis
Kim 2006 [9]	211	-	-	83	Korea	Surgical ward	Retrospective	Suspected acute appendicitis
Kim 2008 [18]	157	Mean 37.1 Range 15 to 84	-	57	Korea	Emergency department	Prospective observational study	Abdominal pain
Lada 2005 [10]	83	Mean 27.5 Range 15 to 75	Male 43 Female 40	88	Argentina	Emergency department	Prospective	Suspected acute appendicitis
Malik 2000 [56]	100	Mean 22 Range 14 to 18	Male 81 Female 19	92	Pakistan	Surgical unit	Prospective	Suspected acute appendicitis
McKay 2007 [31]	150	Mean 34 Range 18 to 76	Male 78 Female 65	32	USA	Emergency department	Retrospective	Abdominal pain
Memon 2009 [32]	100	Mean age 24 Range 13 to 55	Male 65 Female 35	91	Pakistan	Surgical Ward	Prospective study	Suspected acute appendicitis
Muenzer 2010 [47]	28	Test Cohort Mean 11 Validation cohort Mean 11 Range 2 to 17	Test cohort Male 10 Female 10 Validation cohort Male 4 Female 4	54	USA	Emergency department	Unclear	Abdominal pain
Owen 1992 [11]	215		Male 75 Female 70 Children 70	58	Wales	Emergency department	Prospective observational study	GP referral for Suspected acute appendicitis
Petrosyan 2008 [33]	1,630	Male: Median 29 yrs Range 3 to 85 yrs Female: Median 34 yrs Range 2 to 86 yrs	Male 928 Female 702	54	USA	Emergency department	Retrospective	Right lower quadrant pain and suspected acute appendicitis
Rezak 2011 [40]	59	Mean 8.5 Range 3 to 16	Male 43 Female 16	51	USA	Community teaching hospital	Retrospective	Suspected appendicitis
Saidi 2000 [43]	128		Male 49 Female 79	35	Iran	Emergency department	Prospective	Suspected acute appendicitis
Sanabria 2007 [34]	374	Mean 29.5 Range 15 to 71	Male 178 Female 196	55	Columbia	Emergency department	Prospective	Right iliac fossa pain and suspected acute appendicitis
Schneider 2007 [12]	588	Median 11.9 Range 3 to 21		33	USA	Emergency department	Prospective cohort	Suspected acute appendicitis
Shreef 2010 [41]	350	Mean 9.3 Range 8 to 14	Male 228 Female 122	38	Egypt, Saudi Arabia	Emergency department	Prospective	Suspected acute appendicitis
Shrivastava 2004 [57]	100		Male 45 Female 30	78	India	Emergency department	Prospective	Suspected acute appendicitis
Singh 2008 [35]	100	Mean 22.6 Median 25	Male 55 Female 45	62	India	Surgical Ward	Prospective	Suspected acute appendicitis
Soomro 2008 [36]	227	Mean 20.47 Range 10 to 62	Male 150 Females 77	55	Pakistan	Emergency department	Prospective	Suspected acute appendicitis
Stephens 1999 [37]	94	Mean 44 Range 3 to 79	Males 46 Female 48	89	USA	Surgical unit	Retrospective	All patients who underwent appendectomy for suspected acute appendicitis
Tade 2007 [38]	100	Range 17 to 56	Males 63 Female 37	34	Nigeria	Emergency department	Prospective	Right iliac fossa pain and suspected acute appendicitis
Wani 2007 [30]	96	Mean 25.46 Range 7 to 70	Male 48 Female 48	70	India	Surgical unit	Prospective	Suspected acute appendicitis
Yildirim 2008 [39]	143	Mean 34 Range 18 to 76	Male 78 Females 65	85	Turkey	Emergency department	Prospective study	Abdominal pain
Winn 2004 [58]	142			39	Australia	Surgical ward	Retrospective	Suspected acute appendicitis
Subotic 2008 [59]	57	Mean 27.5 Range 16 to 70	Male 27 Female 30	84	Serbia	Emergency department	Prospective	Suspected acute appendicitis
Andersson 2008 [60]	229	Mean 23	Males 105 Females 124	33	Sweden	Emergency department	Prospective	Suspected acute appendicitis
Prabhudesai 2008 [61]	60	Mean 25.4	Male 27 Female 33	40	UK	Emergency department	Prospective	Suspected acute appendicitis