{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T18:37:21Z","timestamp":1791657441951,"version":"4.3.4"},"reference-count":21,"publisher":"Oxford University Press (OUP)","issue":"3","license":[{"start":{"date-parts":[[2024,7,30]],"date-time":"2024-07-30T00:00:00Z","timestamp":1722297600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["R01 AG060975"],"award-info":[{"award-number":["R01 AG060975"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["K08DK124658"],"award-info":[{"award-number":["K08DK124658"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,3,4]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>The self-controlled case-series (SCCS) research design is increasingly used in pharmacoepidemiologic studies of drug\u2013drug interactions (DDIs), with the target of inference being the incidence rate ratio (IRR) associated with concomitant exposure to the object plus precipitant drug vs the object drug alone. While day-level drug exposure can be inferred from dispensing claims, these inferences may be inaccurate, leading to biased IRRs. Grace periods (periods assuming continued treatment impact after days\u2019 supply exhaustion) are frequently used by researchers, but the impact of grace period decisions on bias from exposure misclassification remains unclear. Motivated by an SCCS study examining the potential DDI between clopidogrel (object) and warfarin (precipitant), we investigated bias due to precipitant or object exposure misclassification using simulations. We show that misclassified precipitant treatment always biases the estimated IRR toward the null, whereas misclassified object treatment may lead to bias in either direction or no bias, depending on the scenario. Further, including a grace period for each object dispensing may unintentionally increase the risk of misclassification bias. To minimize such bias, we recommend (1) avoiding the use of grace periods when specifying object drug exposure episodes and (2) including a washout period following each precipitant exposed period.<\/jats:p>\n               <jats:p>This article is part of a Special Collection on Pharmacoepidemiology.<\/jats:p>","DOI":"10.1093\/aje\/kwae231","type":"journal-article","created":{"date-parts":[[2024,8,1]],"date-time":"2024-08-01T07:23:26Z","timestamp":1722497006000},"page":"802-810","source":"Crossref","is-referenced-by-count":4,"title":["Grace periods and exposure misclassification in self-controlled case-series studies of drug\u2013drug interactions"],"prefix":"10.1093","volume":"194","author":[{"given":"Hanxi","family":"Zhang","sequence":"first","affiliation":[{"name":"Center for Real-World Safety and Effectiveness of Therapeutics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Warren B","family":"Bilker","sequence":"additional","affiliation":[{"name":"Center for Real-World Safety and Effectiveness of Therapeutics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Charles E","family":"Leonard","sequence":"additional","affiliation":[{"name":"Center for Real-World Safety and Effectiveness of Therapeutics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Leonard Davis Institute of Health Economics, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sean","family":"Hennessy","sequence":"additional","affiliation":[{"name":"Center for Real-World Safety and Effectiveness of Therapeutics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Leonard Davis Institute of Health Economics, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Todd A","family":"Miano","sequence":"additional","affiliation":[{"name":"Center for Real-World Safety and Effectiveness of Therapeutics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]},{"name":"Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA ,","place":["United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2024,7,30]]},"reference":[{"issue":"1","key":"2025030502235191300_ref1","doi-asserted-by":"publisher","first-page":"228","DOI":"10.2307\/2533328","article-title":"Relative incidence estimation from case series for vaccine safety 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