Text Description: Figure A-2. Flowchart for Selecting Articles

Our evaluation strategy involved two phases. The first phase used broad search terms and review criteria for all 700 article abstracts; the aim was to maximize the probability that all articles that could be useful in any way came to our attention (Table A-3). Four EPC staff independently reviewed the titles and abstracts of the 700 articles identified by the literature searches and excluded those that they agreed clearly did not meet eligibility criteria. When the initial reviewers disagreed or were uncertain, the articles were carried forward to the next review stage in which EPC team members reviewed the full articles and made a final decision about inclusion or exclusion by consensus. A total of 70 articles were examined in phase 2 (Table A-4).

The second phase used more stringent review criteria for full review of the articles themselves to focus our attention on those papers that most directly answered the key questions (Table A-3). Only four studies met all inclusion criteria from phase 2 (Table A-4). We abstracted these four studies into an evidence table, evaluating their quality in detail. Where appropriate in the other parts of the review, we cite articles that are not in the evidence tables; these studies or materials may not directly address the key questions, but they do assist in interpretation of the articles in the evidence tables.

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