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Titolo:
Assessment and control for confounding by indication in observational studies
Autore:
Psaty, BM; Koepsell, TD; Lin, DY; Weiss, NS; Siscovick, DS; Rosendaal, FR; Pahor, M; Furberg, CD;
Indirizzi:
Univ Washington, Cardiovasc Hlth Res Unit, Seattle, WA 98101 USA Univ Washington Seattle WA USA 98101 Hlth Res Unit, Seattle, WA 98101 USA Univ Washington, Dept Med, Seattle, WA 98101 USA Univ Washington Seattle WA USA 98101 ton, Dept Med, Seattle, WA 98101 USA Univ Washington, Dept Epidemiol, Seattle, WA 98101 USA Univ Washington Seattle WA USA 98101 ept Epidemiol, Seattle, WA 98101 USA Univ Washington, Dept Hlth Serv, Seattle, WA 98101 USA Univ Washington Seattle WA USA 98101 ept Hlth Serv, Seattle, WA 98101 USA Univ Washington, Dept Biostat, Seattle, WA 98101 USA Univ Washington Seattle WA USA 98101 Dept Biostat, Seattle, WA 98101 USA Leiden Univ, Ctr Med, Dept Clin Epidemiol, Leiden, Netherlands Leiden Univ Leiden Netherlands Dept Clin Epidemiol, Leiden, Netherlands Univ Tennessee, Dept Prevent Med, Memphis, TN USA Univ Tennessee Memphis TN USA nnessee, Dept Prevent Med, Memphis, TN USA WakeCForest Univ, Bowman Gray Sch Med, Dept Publ Hlth Sci, Winston Salem, N Wake Forest Univ Winston Salem NC USA pt Publ Hlth Sci, Winston Salem, N
Titolo Testata:
JOURNAL OF THE AMERICAN GERIATRICS SOCIETY
fascicolo: 6, volume: 47, anno: 1999,
pagine: 749 - 754
SICI:
0002-8614(199906)47:6<749:AACFCB>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
MYOCARDIAL-INFARCTION; VENOUS THROMBOEMBOLISM; CLINICAL-TRIALS; HEART-DISEASE; RISK; HYPERTENSION; USERS; MISCLASSIFICATION; EPIDEMIOLOGY; PERFORATION;
Keywords:
observational studies; methods; confounding by indication; sensitivity analyses;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Social & Behavioral Sciences
Clinical Medicine
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Psaty, BM Univle,shington, Cardiovasc Hlth Res Unit, Suite 1360,1730 MinorAve, Seatt Univ Washington Suite 1360,1730 Minor Ave Seattle WA USA 98101 t
Citazione:
B.M. Psaty et al., "Assessment and control for confounding by indication in observational studies", J AM GER SO, 47(6), 1999, pp. 749-754

Abstract

In the evaluation of pharmacologic therapies, the controlled clinical trial is the preferred design. When clinical trial results are not available, the alternative designs are observational epidemiologic studies. A traditional concern about the validity of findings from epidemiologic studies is thepossibility of bias from uncontrolled confounding. In studies of pharmacologic therapies, confounding by indication may arise when a drug treatment serves as a marker for a clinical characteristic or medical condition that triggers the use of the treatment and that, at the same time, increases the risk of the outcome under study. Confounding by indication is not conceptually different from confounding by other factors, and the approaches to detect and control for confounding - matching, stratification, restriction, andmultivariate adjustment - are the same. Even after adjustment for known risk factors, residual confounding may occur because of measurement error or unmeasured or unknown risk factors. Although residual confounding is difficult to exclude in observational studies, there are limits to what this "unknown" confounding can explain. The degree of confounding depends on the prevalence of the putative confounding factor, the level of its association with the disease, and the level of its association with the exposure. For example, a confounding factor with a prevalence of 20% would have to increase the relative odds of both outcome and exposure by factors of 4 to 5 before the relative risk of 1.57 would be reduced to 1.00. Observational studies have provided important scientific evidence about the risks associated with several risk factors, including drug therapies, and they are often the onlyoption for assessing safety. Understanding the methods to detect and control for confounding makes it possible to assess the plausibility of claims that confounding is an alternative explanation for the findings of particular studies.

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Documento generato il 03/12/20 alle ore 06:04:51