***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: We included 12 studies (in 13 publications) in this review, but interpretability and generalizability of these studies is difficult and the study designs used were at high risk of bias. The additional yield (calculated by dividing the additional 'unique' yield identified by checking reference lists by the total number of studies found to be eligible within the study) of relevant studies identified through checking reference lists ranged from 2.5% to 42.7%. Only two studies reported yield information by publication type (dissertations and systematic reviews). No cost data were reported although one study commented that it was impossible to isolate the time spent on reference tracking since this was done in parallel with the critical appraisal of each paper, and for that particular study costs were not specifically estimated. There is some evidence to support the use of checking reference lists for locating studies in systematic reviews. However, this evidence is derived from weak study designs. In situations where the identification of all relevant studies through handsearching and database searching is difficult, it would seem prudent that authors of reviews check reference lists to supplement their searching. The challenge, therefore, is for review authors to recognize those situations.
Output:

We found 12 studies that explored whether or not checking reference lists was useful for systematic reviews. These studies reported a range of results, from identifying only a few additional studies (2.5%: 2 of 79 included studies) to identifying many additional studies (42.7%: 111 of 260 included studies) through checking reference lists. Unfortunately, none of the studies looked at how much time or money were spent on the process of checking reference lists, and it was suggested this would be almost impossible to estimate. Unfortunately our findings are based on weak information. The data do suggest that in situations where researchers may have difficulty locating information, checking through the reference lists may be an important way to reduce the risk of missing relevant information.