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 ThermoCool SmartTouch catheter in people with drug‑refractory, recurrent, symptomatic paroxysmal atrial fibrillation (AF).

The strategy was developed for MEDLINE (Ovid interface). The strategy was devised using a combination of subject indexing terms and free text search terms in the title, abstract and keyword heading word fields. The search terms were identified through discussion within the research team, scanning background literature, browsing database thesauri and use of the PubMed PubReMiner tool ( The strategy reflected the nature of the MIB assessments as rapid evidence reviews, with a relatively pragmatic approach being taken. The performance of the draft MEDLINE strategy was assessed by checking retrieval of 9 known, relevant studies identified by the research team at project start; the draft strategy successfully retrieved all the known, relevant studies.

The main structure of the search strategy comprised three concepts:

  • AF

  • Catheter ablation

  • Contact force

The search concepts were combined as follows:

  • AF AND catheter ablation AND contact force

The strategy also combined a line on catheter contact with AF terms, manufacturer terms with the AF and contact force terms, and included stand‑alone search lines on device name‑related terms. These were designed to identify studies which might be missed by the 3 concept approach.

Search concepts were captured using subject headings and text word searches in title, abstract and keyword heading word fields.

The strategy excluded animal studies using a standard algorithm. Non‑English language publications were also excluded from the search results. The search was restricted to studies published from 2010 to date. This date is 1 year prior to the date when the device was CE marked.

The MEDLINE strategy was translated appropriately for the other databases searched. The PubMed search was limited to records not fully indexed for MEDLINE.

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 Effects (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)

  • PubMed (

Evidence selection

A total of 482 records were retrieved from the literature search. After de‑duplication, 279 records remained and 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 240 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 the remaining 39 studies and a full test assessment was done independently by 2 researchers to identify relevant primary research addressing the key clinical outcomes of interest. Studies were excluded for the following reasons:

  • Meta‑analyses with primary studies already included: 3.

  • Multiple contact force devices used and cannot disaggregate results: 3.

  • Review studies/editorials: 3.

  • Incorrect comparator: 3.

  • Device not used: 2.

  • Threshold analysis studies: 2.

  • Indication for use out of scope: 2.

  • Operators were blinded to contact force measurements (not valid intervention): 1.

  • Total: 19.

A total of 20 studies remained which reported on the ThermoCool SmartTouch catheter and addressed the key clinical outcomes of interest. Because of the large evidence base, the highest quality evidence was selected for inclusion in this briefing. This included 2 randomised controlled trials (Kimura et al. 2014; Nakamura et al. 2015), 2 large retrospective cohort studies (Jarman et al. 2015; Lee et al. 2015). An additional 6 studies which were prospective in design (Andrade et al. 2014; Itoh et al. 2015; Makimoto et al. 2015; Marijon et al. 2014; Martinek et al. 2012; Sciarra et al. 2014) were summarised.

The remaining 10 studies included 5 non‑randomised comparative studies which used historical controls (Haldar et al. 2013; Natale et al. 2014; Sigmund et al. 2015; Ullah et al. 2014; Wolf et al. 2015), 4 observational cohort studies (Nakagawa et al. 2013; Providencia et al. 2015; Sotomi et al. 2014; Stabile et al. 2015), and 1 multicentre pilot study (Stabile et al. 2014). All 10 studies were excluded from further analysis.