oncologist, the bronchoscopy was canceled and the patient was started on hormonal therapy.
I have often complained (and heard other attending
physicians complain) that medical students and residents spend more time on the computer than at the bedside with their patients. I am beginning to understand,
however, that the keyboard and the mouse are powerful
diagnostic tools in their own right.
Clifford D. Packer, MD
Correspondence: Dr Packer, Firm B Clinic, Louis Stokes
Cleveland VA Medical Center, 10701 East Blvd, Cleveland, OH 44106 (clifford.packer@med.va.gov).
1. Tonelli MR. The limits of evidence-based medicine. Respir Care. 2001;46:14351440.
2. Schattner A. Simple is beautiful: the neglected power of simple tests. Arch Intern Med. 2004;164:2198-2200.
3. Fukuda M, Takashima H, Fuse H, Hirano S. Prostatic cancer with multiple
pulmonary metastases treated successfully with hormonal therapy: a case report.
Hinyokika Kiyo. 2002;48:499-502.
Diagnostic Accuracy of Natriuretic Peptides
for Heart Failure
S
imple and reliable tests to diagnose heart failure
in elderly patients presenting with symptoms or
signs of impaired left ventricular function would
be of great practical importance. In recent years, brain natriuretic peptides have emerged as a promising, novel test.
Enzyme-linked immunosorbent assay (ELISA), in contrast to radioimmunosorbent assay, does not require long
incubation periods and would be particularly suitable to
assist rapid diagnosis on site in primary and emergency
care settings. The systematic review by Doust et al1 of test
accuracy studies is therefore timely and of great interest,
but not without limitations. We have 3 observations.
First, Doust et al1 included only 3 studies that examined rapid ELISA, despite the fact that at least 4 additional studies of this test system exist. No comprehensive comparisons between the bedside ELISA and
radioimmunosorbent assay can therefore be made. Second, it is unclear how the authors reached the conclusion that brain natriuretic peptide concentrations below
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704
a threshold of 15 pmol/L exclude heart failure in patients in whom the condition is suspected. In their metaanalysis, Doust et al1 calculated an average diagnostic odds
ratio if results for more than 1 cutoff point were reported within a study. It seems inconsistent to average
diagnostic odds ratios across different cutoff points while
claiming that 1 cutoff point is optimal to rule out heart
failure. Table 1 of their article shows the results for each
study for the cutoff point nearest to 15 pmol/L, but these
are not the data that were used in the meta-analysis. Indeed, we were unable to reproduce the combined diagnostic odds ratios for the various subgroups shown in
Figure 1 when repeating analyses using the data presented in Table 1. It is also unclear whether the cutoff
point of 15 pmol/L applies to radioimmunosorbent assay, ELISA, or both. Third, regarding the study by Hobbs
et al,2 we note that the authors included a total of 630
patients from 4 different patient groups, but the total number of patients in the original publication2 is 591. This
discrepancy should be clarified.
In conclusion, the systematic review and metaanalysis of Doust and colleagues1 is an important contribution but also illustrates some of the problems inherent in a meta-analysis of test accuracy studies.3 We
believe that further work is needed to fully elucidate the
potential of the different brain natriuretic peptide tests
in the diagnosis of heart failure.
Markus Battaglia, MD, MPH
Lucas M. Bachmann, MD, PhD
Matthias Egger, MD, MScMFPHM
Correspondence: Dr Egger, MRC Health Services Research Collaboration, Department of Social Medicine, University of Bristol, UK Canynge Hall, Whiteladies Road,
Bristol BS8 2PR, England (Matthias.Egger@bristol
.ac.uk)
1. Doust JA, Glasziou PP, Pietraz E, Dobson AJ. A systematic review of the diagnostic accuracy of natriuretic peptides for heart failure. Arch Intern Med.
2004;164:1978-1984.
2. Hobbs FD, Davis RC, Roalfe AK, Hare R, Davies MK, Kenkre JE. Reliability
of N-terminal pro-brain natriuretic peptide assay in diagnosis of heart failure: cohort study in representative and high risk community populations. BMJ.
2002;324:1498-1500.
3. Egger M, Davey Smith G, Altman DG. Systematic Reviews in Health Care: Metaanalysis in Context. London, England: BMJ Books; 2001.
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