Article type
Year
Abstract
Background: Information from published reports of clinical trials often lacks sufficient details on methods and/or is missing outcome data necessary to pool estimates. As a result, reviewers need to contact study authors, but which correspondence method yields the best response is not clear.
Objectives: To compare response rates from study authors by correspondence method, time since publication, corresponding or secondary authorship, and type of information sought.
Methods: As part of a Cochrane systematic review comparing the effects of inhaled corticosteroids to cromolyn, we contacted study authors of all 25 included trials to clarify methods and/or to obtain missing outcome data. Authors listed as corresponding authors were contacted by e-mail if available, by post if e-mail was unavailable or there was no response to e-mail, and by fax if e-mail and post were both unavailable or there was no response to either. Remaining authors were contacted if there was no response by the corresponding author. Time from initial correspondence to response was recorded.
Results: Fifteen authors (60%) responded to our information requests. E-mail resulted in fewer attempts, a greater response rate, and a shorter response time than post or fax (see table below). Requests for clarification of methods resulted in a greater response (50% vs. 32%, p=0.03) than requests for missing data. Authors of studies published after 1990 were as likely to respond (67% vs. 50%, p=0.45) as authors of studies published earlier. Similarly, corresponding authors were no more likely to respond (58% vs. 9%, p=0.44) than secondary authors, although few secondary authors were contacted.
Conclusions: In this systematic review, correspondence with study authors by e-mail resulted in the greatest response rate with the fewest attempts and the shortest time to respond. Reviewers should also consider the type of information requested as it may influence responses.
E-mail (N=16)
Post (N=11)
Fax (N=2)
Mean Attempts (SD)
1.8 (1.5)
2.9 (1.3)
2.0 (0.0)
Response Rate (%)
62.5
27.3
0.0
Mean Days to Respond (SD)
36.3 (38.2)
65.0 (35.7)
N/A
Objectives: To compare response rates from study authors by correspondence method, time since publication, corresponding or secondary authorship, and type of information sought.
Methods: As part of a Cochrane systematic review comparing the effects of inhaled corticosteroids to cromolyn, we contacted study authors of all 25 included trials to clarify methods and/or to obtain missing outcome data. Authors listed as corresponding authors were contacted by e-mail if available, by post if e-mail was unavailable or there was no response to e-mail, and by fax if e-mail and post were both unavailable or there was no response to either. Remaining authors were contacted if there was no response by the corresponding author. Time from initial correspondence to response was recorded.
Results: Fifteen authors (60%) responded to our information requests. E-mail resulted in fewer attempts, a greater response rate, and a shorter response time than post or fax (see table below). Requests for clarification of methods resulted in a greater response (50% vs. 32%, p=0.03) than requests for missing data. Authors of studies published after 1990 were as likely to respond (67% vs. 50%, p=0.45) as authors of studies published earlier. Similarly, corresponding authors were no more likely to respond (58% vs. 9%, p=0.44) than secondary authors, although few secondary authors were contacted.
Conclusions: In this systematic review, correspondence with study authors by e-mail resulted in the greatest response rate with the fewest attempts and the shortest time to respond. Reviewers should also consider the type of information requested as it may influence responses.
E-mail (N=16)
Post (N=11)
Fax (N=2)
Mean Attempts (SD)
1.8 (1.5)
2.9 (1.3)
2.0 (0.0)
Response Rate (%)
62.5
27.3
0.0
Mean Days to Respond (SD)
36.3 (38.2)
65.0 (35.7)
N/A