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BMJ. 2018 Apr 3;361:k1180. doi: 10.1136/bmj.k1180.

Differences in rates of switchbacks after switching from branded to authorized generic and branded to generic drug products: cohort study.

Author information

1
Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02120, USA.
2
Office of Generic Drugs, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, MD, USA.
3
Harvard School of Public Health, Boston, MA, USA.

Abstract

OBJECTIVES:

To compare rates of switchbacks to branded drug products for patients switched from branded to authorized generic drug products, which have the same active ingredients, appearance, and excipients as the branded product, with patients switched from branded to generic drug products, which have the same active ingredients as the branded product but may differ in appearance and excipients.

DESIGN:

Observational cohort study.

SETTING:

Private (a large commercial health plan) and public (Medicaid) insurance programs in the US.

PARTICIPANTS:

Beneficiaries of a large US commercial health insurer between 2004 and 2013 (primary cohort) and Medicaid beneficiaries between 2000 and 2010 (replication cohort).

MAIN OUTCOME MEASURES:

Patients taking branded products for one of the study drugs (alendronate tablets, amlodipine tablets, amlodipine-benazepril capsules, calcitonin salmon nasal spray, escitalopram tablets, glipizide extended release tablets, quinapril tablets, and sertraline tablets) were identified when they switched to an authorized generic or a generic drug product after the date of market entry of generic drug products. These patients were followed for switchbacks to the branded drug product in the year after their switch to an authorized generic or a generic drug product. Cox proportional hazard models were used to estimate hazard ratios and 95% confidence intervals after adjusting for demographics, including age, sex, and calendar year. Inverse variance meta-analysis was used to pool adjusted hazard ratios across all drug products.

RESULTS:

A total of 94 909 patients switched from branded to authorized generic drug products and 116 017 patients switched from branded to generic drug products and contributed to the switchback analysis. Unadjusted incidence rates of switchback varied across drug products, ranging from a low of 3.8 per 100 person years (for alendronate tablets) to a high of 17.8 per 100 person years (for amlodipine-benazepril capsules), with an overall rate of 8.2 per 100 person years across all drug products. Adjusted switchback rates were consistently lower for patients who switched from branded to authorized generic drug products compared with branded to generic drug products in the primary cohort (pooled hazard ratio 0.72, 95% confidence interval 0.64 to 0.81). Similar results (0.75, 0.62 to 0.91) were observed in the replication cohort.

CONCLUSION:

Switching from branded to authorized generic drug products was associated with lower switchback rates compared with switching from branded to generic drug products.

PMID:
29615391
PMCID:
PMC5881140
DOI:
10.1136/bmj.k1180
[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: JJG is principal investigator of research grants from Novartis Pharmaceuticals Corporation and Eli Lilly and Company to the Brigham and Women’s Hospital. JGG is a for Optum, Inc and Aetion, Inc. RJD is principal investigator of a research grant from Merck to the Brigham and Women’s Hospital. JRR is a consultant to Aetion Inc. SKD and SR are employees of the FDA.

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