On 2017 Apr 05, Julie Glanville commented:

As we note in the Methods section of our paper, this paper is informed by an update of a systematic review:

"For the update to the systematic review, we searched 18 databases, websites, trial registries and three conference websites between February and March 2016. The search strategy for MEDLINE is shown in Supplemental Fig. 1 (Fig. S1) and the other searches are available on request. This search strategy was originally developed in 2013, and then updated for this analysis taking into account relevant recent changes in indexing [19, 20]. The searches were not limited by date, language, or document type. The information sources searched are shown in Supplemental Table 1 (Table S1). Search results were downloaded into Endnote and de-duplicated against each other and against the results of the original review."

Figure 1 in the supplementary material shows the Medline update search. Although it is a search carried out to identify new records since the original searches, we did not limit to recent years but reran the search for all years. This resulted in 6845 records. However, many of these records had been processed in the initial SR, so "Search results were downloaded into Endnote and de-duplicated against each other and against the results of the original review". This resulted in a much lower number of records which needed to be assessed for relevance from Medline in the update as can be seen in Table S2. In Table S2 the second column shows the number of records downloaded before deduplication against the original search results and the third column shows the number of records assessed for relevance after deduplication against the original search results. Hence the number difference. We acknowledge that there has been a transposition error for the Medline results in Table S2 - the search resulted in 6845 records and we have entered 2845 by mistake. We will correct the transposition error.

Despite what we say in the Methods section, the full search strategies for the original search and the update searches are in the supplementary material at page 28 onwards.

On 2017 Apr 04, Wichor Bramer commented:

The authors of this article seen to have made a mistake in their registration of results per database. The supplements show that EMBASE alone retrieved over 7000 results and SCI more than 6000. Yet the total number of articles after deduplication is 5500.

Only the Medline search is provided in detail. The number of results shown in the search strategy seems to be 6800, whereas in the overview table of all databases the number is 2800.

It is recommended to add the search strategies for all databases and to keep a good and clear track of the results per database before and after deduplication.

On 2017 Apr 04, Wichor Bramer commented:

The authors of this article seen to have made a mistake in their registration of results per database. The supplements show that EMBASE alone retrieved over 7000 results and SCI more than 6000. Yet the total number of articles after deduplication is 5500.

Only the Medline search is provided in detail. The number of results shown in the search strategy seems to be 6800, whereas in the overview table of all databases the number is 2800.

It is recommended to add the search strategies for all databases and to keep a good and clear track of the results per database before and after deduplication.

On 2017 Apr 05, Julie Glanville commented:

As we note in the Methods section of our paper, this paper is informed by an update of a systematic review:

"For the update to the systematic review, we searched 18 databases, websites, trial registries and three conference websites between February and March 2016. The search strategy for MEDLINE is shown in Supplemental Fig. 1 (Fig. S1) and the other searches are available on request. This search strategy was originally developed in 2013, and then updated for this analysis taking into account relevant recent changes in indexing [19, 20]. The searches were not limited by date, language, or document type. The information sources searched are shown in Supplemental Table 1 (Table S1). Search results were downloaded into Endnote and de-duplicated against each other and against the results of the original review."

Figure 1 in the supplementary material shows the Medline update search. Although it is a search carried out to identify new records since the original searches, we did not limit to recent years but reran the search for all years. This resulted in 6845 records. However, many of these records had been processed in the initial SR, so "Search results were downloaded into Endnote and de-duplicated against each other and against the results of the original review". This resulted in a much lower number of records which needed to be assessed for relevance from Medline in the update as can be seen in Table S2. In Table S2 the second column shows the number of records downloaded before deduplication against the original search results and the third column shows the number of records assessed for relevance after deduplication against the original search results. Hence the number difference. We acknowledge that there has been a transposition error for the Medline results in Table S2 - the search resulted in 6845 records and we have entered 2845 by mistake. We will correct the transposition error.

Despite what we say in the Methods section, the full search strategies for the original search and the update searches are in the supplementary material at page 28 onwards.