--- title: "Determinants of generic drug substitution in the U.S. | Sutter Health" description: "Mail-order pharmacies, as often required by pharmacy benefits managers, lessen generic use for many classes. These pharmacies may require more regulation." url: "https://www.sutterhealth.org/research/publications/determinants-of-generic-drug-substitution-in-the-us-1055312368" --- 1. [Home](https://www.sutterhealth.org/) / 2. [Research](https://www.sutterhealth.org/research) / 3. [Research publications](https://www.sutterhealth.org/research/publications) / 4. Determinants of generic drug substitution in the U.S. # Determinants of generic drug substitution in the United States. Segal JB, Onasanya O, Daubresse M, Lee CY, Moechtar M, Pu X, Dutcher SK, & Romanelli RJ. _Ther Innov Regul Sci. 2168479018820050. doi: 10.1177/2168479018820050. \[Epub ahead of print\]_ 2019-01-13 ## Abstract BACKGROUND: Some classes of drugs have lower than optimal uptake of generic products. We aimed to understand the determinants of generic drug substitution across classes. METHODS: We conducted a cross-sectional analysis of data from the 2013 MarketScan Commercial Claims and Encounters Database from Truven Health Analytics. We quantified generic substitution rates (GSR) for 26 drug classes, choosing one representative week in November 2013. We used mixed-effects logistic regression to estimate the independent relationship between the determinants of interest and generic substitution for 8 classes with low generic utilization. RESULTS: The GSRs for most classes exceeded 90%, although some were much lower including thyroid hormones (64%), androgens (74%), estrogens (71%), and hydantoin-type anticonvulsants (72%). The determinants of generic substitution varied across classes, albeit with important patterns. Patients using a mail order pharmacy had significantly less generic substitution than patients filling at retail pharmacies for 5 of the 8 studied classes; two additional classes showed no relationship between pharmacy type and generic use. Men relative to women and patients taking more medications were more likely to use generics for most classes. State substitution laws and patient consent laws were largely inconsequential regarding generic substitution. CONCLUSIONS: Policies are needed to support the use of safe, effective and often lower cost generic drugs, when available. Mail order pharmacies, as often required by pharmacy benefits managers, lessen generic use for many classes. These pharmacies may require additional regulatory oversight if this adversely impacts patients. [PubMed abstract](https://www.ncbi.nlm.nih.gov/pubmed/30636440) ## Research topics - [Health Policy](https://www.sutterhealth.org/research-search-results?query=%22%5C%22Health+Policy%5C%22%22) - [Medical Informatics](https://www.sutterhealth.org/research-search-results?query=%22%5C%22Medical+Informatics%5C%22%22) ## Related publications [View all publications](https://www.sutterhealth.org/research-search-results?verticalKey=research_publication) - Publication ### [Policy-oriented research on improved physician incentives for higher value health care.](https://www.sutterhealth.org/research/publications/improved-md-incentives-higher-value-healthcare-1055312438) Luft HS. Health Serv Res. doi: 10.1111/1475-6773.12423. \[Epub ahead of print\] 2015 Nov 17 - Publication ### [Meta-analysis 101: what you want to know in the era of comparative effectiveness.](https://www.sutterhealth.org/research/publications/understand-meta-analyses-in-comparative-effectiveness-1055312642) Jones JB, Blecker S, Shah NR. Am Health Drug Benefits. 1(3):38-43. 2008 Apr 01 - Publication ### [A clinician's guide to privacy and communication in the ICU.](https://www.sutterhealth.org/research/publications/clinician-privacy-communication-icu-1055312509) Francis L, Vorwaller MA, Aboumatar H, Frosch DL, Halamka J, Rozenblum R, Rubin E, Lee BS, Sugarman J, Turner K, Brown SM; Privacy, Access, and Engagement Task Force of the Libretto Consortium of the Gordon and Betty Moore Foundation. Crit Care Med. \[Epub ahead of print\] 2016 Dec 02 - Publication ### [Electronic health record logs indicate that physicians split time evenly between seeing patients and desktop medicine.](https://www.sutterhealth.org/research/publications/mds-split-time-evenly-see-pts-desktop-med-1055312310) Tai-Seale M, Olson CW, Li J, Chan AS, Morikawa C, Durbin M, Wang W, Luft HS. Health Aff. 36:655-662; doi:10.1377/hlthaff.2016.0811. 2017 Apr 01 - Publication ### [International Committee for Monitoring Assisted Reproductive Technologies World Report: Assisted Reproductive Technology 2006.](https://www.sutterhealth.org/research/publications/world-report-assisted-reproductive-tech-2006-1055312923) Mansour R, Ishihara O, Adamson GD, Dyer S, de Mouzon J, Nygren KG, Sullivan E, Zegers-Hochschild F. Hum Reprod. 29(7):1536-51. Epub 2014 May 2. 2014 Jul 01 [View all publications](https://www.sutterhealth.org/research-search-results?verticalKey=research_publication) ```json {"@context":"https://schema.org","@type":"MedicalOrganization","name":"Sutter Health","@id":"https://www.sutterhealth.org/#medicalorganization","url":"https://www.sutterhealth.org","logo":"https://www.sutterhealth.org/static/images/sutter-health-logo.svg","address":{"@type":"PostalAddress","streetAddress":"2200 River Plaza Drive","addressLocality":"Sacramento","addressRegion":"CA","postalCode":"95833","addressCountry":"US"},"areaServed":{"@type":"AdministrativeArea","name":"California"},"sameAs":["https://www.facebook.com/SutterHealth","https://www.instagram.com/sutterhealth/","https://x.com/SutterHealth","https://www.youtube.com/sutterhealth","https://www.linkedin.com/company/sutter-health","https://en.wikipedia.org/wiki/Sutter_Health"]} ``` ```json {"@context":"https://schema.org","@type":"BreadcrumbList","@id":"https://www.sutterhealth.org/research/publications/determinants-of-generic-drug-substitution-in-the-us-1055312368#breadcrumblist","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://www.sutterhealth.org/"},{"@type":"ListItem","position":2,"name":"Research","item":"https://www.sutterhealth.org/research"},{"@type":"ListItem","position":3,"name":"Research publications","item":"https://www.sutterhealth.org/research/publications"},{"@type":"ListItem","position":4,"name":"Determinants of generic drug substitution in the U.S."}]} ``` ```json {"@context":"https://schema.org","@type":"MedicalScholarlyArticle","@id":"https://www.sutterhealth.org/research/publications/determinants-of-generic-drug-substitution-in-the-us-1055312368#medicalscholarlyarticle","name":"Determinants of generic drug substitution in the United States.","headline":"Determinants of generic drug substitution in the U.S.","abstract":"BACKGROUND: Some classes of drugs have lower than optimal uptake of generic products. We aimed to understand the determinants of generic drug substitution across classes. METHODS: We conducted a cross-sectional analysis of data from the 2013 MarketScan Commercial Claims and Encounters Database from Truven Health Analytics. We quantified generic substitution rates (GSR) for 26 drug classes, choosing one representative week in November 2013. We used mixed-effects logistic regression to estimate the independent relationship between the determinants of interest and generic substitution for 8 classes with low generic utilization. RESULTS: The GSRs for most classes exceeded 90%, although some were much lower including thyroid hormones (64%), androgens (74%), estrogens (71%), and hydantoin-type anticonvulsants (72%). The determinants of generic substitution varied across classes, albeit with important patterns. Patients using a mail order pharmacy had significantly less generic substitution than patients filling at retail pharmacies for 5 of the 8 studied classes; two additional classes showed no relationship between pharmacy type and generic use. Men relative to women and patients taking more medications were more likely to use generics for most classes. State substitution laws and patient consent laws were largely inconsequential regarding generic substitution. CONCLUSIONS: Policies are needed to support the use of safe, effective and often lower cost generic drugs, when available. Mail order pharmacies, as often required by pharmacy benefits managers, lessen generic use for many classes. These pharmacies may require additional regulatory oversight if this adversely impacts patients.","description":"Mail-order pharmacies, as often required by pharmacy benefits managers, lessen generic use for many classes. 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