Diagnostic et traitement des varices des membres inférieurs - KCE

12 Varicose Veins KCE Reports 164
2.2 ASSESSING METHODOLOGICAL QUALITY AND RISK OF
BIAS
2.2.1 Diagnostic studies
The methodological quality of diagnostic studies was assessed using the QUADAS tool 38
by a team of three reviewers (FA, MK, SM). The papers were divided amongst the three
reviewers and then swapped over for double quality assessment. Any uncertainties
were discussed between the three reviewers. The QUADAS tool is structured as a list
of 14 questions addressing aspects of the study design such as patient population, the
reference and index tests and whether there is blinding of the tests (see appendix
9.2.1). These questions are scored “yes”, “no” or “unclear” and an assessment of the
methodological quality of each study involved investigation of the individual quality items
rather than using a combined quality score 38 . The results are in appendix 9.2.2.
2.2.2 Systematic reviews
The methodological quality of systematic reviews and associated risk of bias were rated
using the SIGN tool a . This tool uses a scale of ratings ranging from (well covered,
adequately addressed, not addressed, not reported and not applicable).The assessment
of the risk of bias in the included SRs was conducted by a team of three reviewers
(FA,MK,SM) who pre-agreed the ratings before beginning quality analysis. In order for
systematic reviews to be included, three of the four following criteria had to be rated as
“well covered” or “adequately addressed”:
• Appropriate and clearly focussed study question;
• Description of methodology; sufficiently rigorous literature searches (defined
according to SIGN SR quality appraisal tool e.g. Medline, EMBASE, Cochrane
and hand searching of reference lists);
• Quality and methodological strengths and weaknesses of identified data
assessed and taken into account.
The results of the quality appraisal of systematic reviews are in Appendix 9.3.
2.2.3 Randomised controlled trials
The methodological quality of selected RCTs was rated using a modified version of the
SIGN tool. The assessment of the risk of bias in the included RCTs was conducted by a
team of three reviewers (FA, MK, SM). In order for RCTs to be included, two of the
four following criteria had to be rated as “well covered” or “adequately addressed”:
• Randomisation;
• Blinding of outcome assessment;
• Treatment groups comparable at baseline;
• Description of dropouts and withdrawals.
The quality appraisal tool and the results are in Appendix 9.5.
2.3 DATA EXTRACTION
2.3.1 Diagnostic studies
The DET for diagnostic studies captured the following information: reference, country,
patient numbers and characteristics, index test, reference test, diagnostic accuracy
outcomes e.g. sensitivity, specificity, clinical significant outcomes e.g. decision to
perform surgery, results and description of quality appraisal (see appendix 9.2.3).
Data extraction of the papers was performed by a reviewer (FA) into a pre-prepared
Word ® table. Extraction was verified in full by a second reviewer (MK). Any
discrepancies were resolved through discussion with the third reviewer (SM).
a http://www.sign.ac/methodology/checklists.html