Characteristics of clinical trials assessing antimicrobial treatment of bovine respiratory disease, 1970-2005.
OBJECTIVE
To evaluate reporting of key study design features and study outcomes in trials of antimicrobial treatment of bovine respiratory disease (BRD) in North American feedlots.


METHODS
Systematic review.


METHODS
29 manuscripts (41 studies) reporting antimicrobial treatment of BRD in North American feedlot cattle.


METHODS
A search of the electronic citation databases AGRICOLA, Commonwealth Agricultural Bureau, and PubMed was conducted to identify relevant manuscripts published between 1970 and 2005. Key study design features were extracted by 2 reviewers.


RESULTS
12 of 29 (41%) manuscripts did not disclose a funding source, and 21 (72%) had an author clearly identified as an employee of a pharmaceutical company. At the study level, 36 of 41 (88%) studies reported a random method of treatment allocation, 9 (22%) described the method of allocation sequence generation, 20 (49%) reported that study investigators were blinded to treatment, and 3 (7%) included a study size justification. No studies described the null hypothesis to be tested. Thirty-seven (90%) studies reported at least 3 outcomes; the largest number of outcomes reported was 14. It was not possible to conduct the statistical analysis as originally planned because it was not possible to discern the primary outcome for the majority of studies.


CONCLUSIONS
Many studies did not report key study design features that would assist critical evaluation by readers. It was not clear whether the studies failed to use the design features or failed to report them. Several nondesign features, such as reporting of the null hypothesis, a primary outcome, and sample size rationale, represent relatively new standards for reporting; however, reporting these features would substantially clarify the study objective.
O'Connor
Annette M
AM
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA. oconnor@iastate.edu
Wellman
Nickolas G
NG
Rice
Michael
M
Funk
Lucas
L
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy*; D012140:Respiratory Tract Diseases / Q000188:drug therapy / Q000662:veterinary*; D013997:Time Factors
D000900:Anti-Bacterial Agents