Background: The Cochrane HSSS is often used to retrieve reports of randomized trials in MEDLINE. However, its precision is low, yielding many irrelevant records. Improvements in indexing and reporting of trials have made it easier to retrieve reports of trials and may have affected the usefulness of the HSSS.
Objectives: To detect term(s) in the Cochrane HSSS with high sensitivity that improve precision in retrieving reports of randomized trials in Africa in HIV/AIDS.
Methods: The Cochrane HSSS was added, term-by-term, to an African HIV/AIDS search strategy to identify reports of randomized trials in MEDLINE. The titles and abstracts of the records retrieved were read by two handsearchers and checked by a clinical epidemiologist. The sensitivity and precision of each term were calculated.
Results: Of 7,719 records retrieved, 285 were judged to be reports of trials (204 randomized (RCTs); 81 possibly randomized or quasirandomized (CCTs)). Phase III had the highest sensitivity (92%). Precision for the strategy as a whole was very low (3.7%). One term, "random*[tw]" retrieved all RCTs found by our search, with a precision of 29%, but missed 79 CCTs. The least sensitive terms, yielding no relevant records, were "(doubl* AND mask*)[tw]" and terms containing "trebl*" or "tripl*", except for "(tripl* AND blind*)[tw]". The term with the highest precision was "Double-blind Method [MeSH]" (76%).
Conclusions: To retrieve all RCTs and CCTs found by our search, only seven terms are needed but precision remains low (4.3%). Recently developed objective methods for search strategy design which identify terms occurring frequently in relevant records and which discriminate efficiently between study designs, are being used to revise the Cochrane HSSS.1
1. Glanville JM, Lefebvre C, Miles JNV, Camosso-Stefinovic J. How to identify randomized controlled trials in MEDLINE: ten years on. Journal of the Medical Library Association 2006; 94(2):130-6.