Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews

Table 1 Items identified through the factor analysis

	Original instrument (item no)	1	2	3	4	5	6	7	8	9	10	11
1 Protocol	Sacks	.58
2 Literature Search	Sacks				.82
3 List of Trials Analyzed	Sacks		.75
4 Log of Rejected Trials	Sacks								.68
5 Treatment Assignment	Sacks		.80
6 Ranges of Patients	Sacks
7 Range of Treatment	Sacks		.88
8 Range of Diagnosis	Sacks		.80
9 CombinabilityCriteria	Sacks									.88
10 Measurement	Sacks				.57
11 Selection Bias	Sacks	.85
12 Data abstraction	Sacks	.50
13 Inter-observer Agreement	Sacks	.65
14 Sources of Support	Sacks								.64
15 Statistical Methods	Sacks			.81
16. Statistical Errors	Sacks
17 Confidence Intervals	Sacks			.73
18 Subgroup Analysis	Sacks
19 Quality Assessment	Sacks					.77
20 Varying Methods	Sacks					.63
21 Publication Bias 1	Sacks						.77
22 Caveats	Sacks
23 Economic Impact	Sacks											.84
24 Language 1	Added to Sacks							.79
25 Search Strategy	OQAQ (1)				.81
26 Was the search comprehensive	OQAQ (2)
27 Criteria used for deciding which studies to include	OQAQ (3)
28 Was bias in the selection avoided	OQAQ (4)	.81
29 Were the criteria used for assessing the validity reported?	OQAQ (5)					.75
30 Was the validity of all studies referred to in the text assessed using appropriate criteria	OQAQ (6)				.53						.60
31 Were the methods used to combine the finding of the relevant studies reported	OQAQ (7)
32 Were the findings of the relevant studies combined appropriately	OQAQ (8)			.78
33 Were the conclusions made by the author supported by the data	OQAQ (9)			.68
34 Overall Summary	OQAQ (10)
35. Publication Bias 2	Additional (1)						.80
36 Publication Status	Additional (2)							.77
37 Language 2	Additional (3)							.63

ISSN: 1471-2288