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Leukocyte Esterase Tests Detect Pyuria, Not Bacteriuria
- Edward J. Boyko, MD
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
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TO THE EDITOR:
The spectrum bias described recently by Lachs and associates[1] with regard to the rapid dipstick test for UTI may be due in whole or in part to the effects of the imperfect reference test for UTI chosen as their “gold standard.” The criterion for a positive urine culture of greater than 105 colony-forming units (CFU)/mL is not 100% sensitive and specific for UTI, as one expects of an ideal “gold standard” that accurately separates those with and those without disease.
Use of an imperfect reference test in the evaluation of diagnostic test sensitivity and specificity has predictable effects on the performance of the diagnostic test [2].
In the study by Lachs and colleagues[1], the rapid dipstick method showed a sensitivity of 0.92 and a specificity of 0.42 in the high-probability UTI pretest group but a lower sensitivity (0.56) and a higher specificity (0.78) in the low-probability UTI pretest group.
The authors recommended that clinicians use sensitivities and specificities generated by diagnostic test evaluations done in subgroups clinically similar to those encountered in their practices; this would not correct error due to reference test misclassification. Recent advances in this direction have been made by Schulzer and colleagues [3], but no resolution has yet been achieved.
Edward J. Boyko
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
- Copyright ©2004 by the American College of Physicians
