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Search strategy and evidence selection

Search strategy and evidence selection

Search strategy

The search strategy was designed to identify evidence on the clinical and cost effectiveness of ultrasound elastography for breast imaging. It comprised 2 concepts: the population (breast imaging) and the intervention (ultrasound elastography). The strategy excluded animal studies and non‑English language publications. No additional filters for study design were applied. The results were limited to studies published from 2005 to the time of publication, reflecting that the manufacturer was founded in 2005.

The final strategy was peer‑reviewed by an independent information specialist.

The following databases were searched:

  • Cochrane Central Register of Controlled Trials (Cochrane Library, Wiley)

  • Cochrane Database of Systematic Reviews (Cochrane Library, Wiley)

  • Database of Abstracts of Reviews of Effect (Cochrane Library, Wiley)

  • Embase (Ovid SP)

  • Health Technology Assessment Database (Cochrane Library, Wiley)

  • MEDLINE and MEDLINE in Process (Ovid SP)

  • NHS Economic Evaluation Database (Cochrane Library, Wiley).

The manufacturer also provided a bibliography of 53 studies of peer‑reviewed publications reporting results of clinical studies which looked at the use of Aixplorer ShearWave Elastography in breast imaging. This identified 3 additional papers which were published too recently to have been included in any of the databases searched.

Evidence selection

A total of 1305 records were retrieved from the literature search (1302 from the database searches and 3 provided by the manufacturer). After de‑duplication, 842 records remained. An initial 262 records were excluded at first pass as being animal or plant studies, obviously irrelevant interventions or obviously irrelevant populations. The remaining 580 records were sifted against the inclusion criteria at title and abstract level.

Records were sifted independently by 2 researchers. Any disagreements were discussed and agreement was reached in all cases, so a third independent arbiter was not required. The first sift removed 532 records based on the following exclusion criteria:

  • articles of poor relevance against search terms

  • publication types that were out of scope

  • non‑English language studies

  • conference abstracts

  • review articles.

Full articles were retrieved for 47 of the remaining 48 studies, with 1 ordered but not received within the briefing production timeline. Full text assessment was done independently by 2 researchers to identify relevant primary research addressing the key outcomes of interest (that is, diagnostic accuracy studies reporting quantitative Aixplorer ShearWave Elastography parameters against a reference standard [biopsy]). Papers excluded at this stage included:

  • studies on different commercial or experimental systems: 8

  • studies focusing on intra‑ and inter‑observer outcomes: 3

  • studies reporting only qualitative data (visual colour map): 4

  • correlation studies and/or other post hoc analyses: 5

  • population has wrong pathology (e.g. malignancy already diagnosed): 2

  • technical study (phantom tissue): 1

  • secondary study (e.g. review): 4

  • conference abstracts: 4

  • non‑English paper: 2

  • total: 33.

Fourteen studies remained, which were all diagnostic accuracy studies that included a reference standard. This was judged to be disproportionate number for the purposes of a briefing, and so a further exclusion was applied in order to focus this briefing only on diagnostic accuracy studies against a reference standard which also estimated the potential impact of the technology on clinical pathways (for example, with data on BI‑RADS reclassification of lesions between categories 3 and 4a and/or estimated change in biopsy rates). This additional step excluded a further 9 diagnostic accuracy studies. These 9 papers all reported threshold Aixplorer ShearWave Elastography parameters for determining malignancy in breast lesions, but the authors did not describe clinical impact as a primary outcome of interest. This left 5 diagnostic accuracy studies with reported outcomes relevant to clinical pathways.