We appreciate the letter from Drs. Petty and Mannino regarding the USPSTF's recent recommendation against screening for COPD by using spirometry (1). Their comments provide us the opportunity to emphasize some important issues that the USPSTF considered in making this recommendation.

Identifying a disease earlier in its natural course does not automatically improve health outcomes. Clinicians should screen patients only if effective interventions are more beneficial during the asymptomatic disease stage than at clinical diagnosis and if the harms of screening or treatment do not outweigh the benefits. The USPSTF's review of the evidence (2) found that for more than 90% of individuals without respiratory symptoms who would have airflow obstruction on spirometry, the sole effective therapy was tobacco cessation interventions, which the USPSTF already recommends for all adult smokers (3). Even accounting for the few individuals who might gain symptomatic relief from medications, several hundred patients would need to be screened with spirometry to defer a single COPD exacerbation. The USPSTF judged that the harms of such screening—false-positive test results leading to adverse effects from treatment (for example, tachycardia or urinary retention), coupled with the substantial time and effort required by patients and the health care system—were at least equal to this small potential benefit.

Although Drs. Petty and Mannino argue that providing smokers with spirometry results may motivate them to quit smoking, no studies they cite were designed to appropriately test this hypothesis. For example, because all of the participants in the randomized trial by Parkes and colleagues (4) had spirometry, the only definite conclusion that can be drawn is that communicating spirometry results to smokers in understandable terms (lung age) was more effective than providing the underlying clinical data.

The USPSTF does not discourage clinicians from using spirometry to diagnose unexplained respiratory symptoms or to monitor patients with an established pulmonary diagnosis. We are puzzled by the assertion that recommending against inappropriate overuse of spirometry (screening) will lead to underuse of the test in appropriate (diagnostic or monitoring) clinical situations.

Although the American College of Physicians' COPD practice guideline (5) came to the same conclusion about screening as did the USPSTF, the USPSTF includes a broad representation of primary care clinicians and generalists and has an independent guideline development process. The difference in the composition of and processes used by these 2 groups support the idea that evidence-based guidelines are highly reliable.