Document Detail

Consequences of diagnostic errors in mastitis therapy trials.
MedLine Citation:
PMID:  3216055     Owner:  NLM     Status:  MEDLINE    
The effect of errors that occur in the diagnosis of intramammary infectious mastitis on the precision of experiments measuring the efficacy of mastitis therapy has been investigated. Diagnostic errors within the range found by experienced workers can create large biases in the apparent cure rate of therapy particularly at cure rates of less than 0.5. Using confirmed methods of diagnosis rather than single samples and reducing the probabilities of false positive and false negative diagnoses to 0.01 and 0.05 respectively, the biases in the apparent cure rates are reduced to acceptable levels. A method is given for calculating the rates of occurrence of false positive and false negative diagnoses from the results of trials using confirmed diagnoses. These errors cannot be calculated from therapy trial data when diagnosis is based on single milk samples. Because the bias in the measurements of the cure rate is greatest at the lowest levels of elimination, estimates of spontaneous recovery in untreated quarters have the greatest error. For this reason experiments incorporating an untreated control group of infected quarters usually reduce the precision of the therapy trials. An experiment in which the efficacy of a test product is measured relative to a reference product has advantages. It minimizes the difficulties arising from scale of measurement, diagnostic errors and herd differences in response rate, and makes possible comparisons between trials. Further investigations are required on the importance of spontaneous recovery, particularly for studies of Escherichia coli therapy and dry period therapy. The results of this investigation have relevance to all types of mastitis investigation that measure the change in mastitis status of udder quarters, i.e. new infection rates.
S V Morant; F H Dodd; R P Natzke
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of dairy research     Volume:  55     ISSN:  0022-0299     ISO Abbreviation:  J. Dairy Res.     Publication Date:  1988 Aug 
Date Detail:
Created Date:  1989-02-28     Completed Date:  1989-02-28     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  2985125R     Medline TA:  J Dairy Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  315-29     Citation Subset:  IM    
Milk Marketing Board, Thames Ditton, Surrey, UK.
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MeSH Terms
Diagnostic Errors / veterinary
Drug Evaluation / veterinary*
Mastitis, Bovine / diagnosis*,  drug therapy

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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