Study designs of evaluations included in the review
The authors did not specify any a priori inclusion criteria relating to the study design. It appears that studies of any design were eligible for inclusion. The authors did not report the exact study designs included.
Specific interventions included in the review
The authors stated that studies were eligible for inclusion if they performed both mammography and ultrasonography on the same participants. In actuality, the included studies compared either mammography versus ultrasonography, or mammography plus ultrasonography versus mammography alone.
Reference standard test against which the new test was compared
To be eligible for inclusion in the review, studies had to use the 'gold' standard of pathology (preferably from histological needle biopsy or surgery) or follow-up of patients with negative imaging results, preferably for one year or longer.
Participants included in the review
Studies of people undergoing screening for breast cancer were eligible for inclusion. The median prevalence of breast cancer in the included studies was 45% (range: 5.5 to 72.2). The mean age of the participants ranged from 37 to 54 years.
Outcomes assessed in the review
To be eligible for inclusion, studies had to report sensitivity and specificity statistics, or data that allowed the authors to calculate the sensitivity and specificity. The natural logarithm of the diagnostic odds ratio (OR) was used to compare the diagnostic performance of ultrasonography and mammography.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.