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Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study

BACKGROUND: Several countries have introduced generic substitution, but few studies have assessed its effect on refill adherence. This study aimed to analyse whether generic substitution influences refill adherence to statin treatment. METHODS: Between 1 July 2006 and 30 June 2007, new users of simv...

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Autores principales: Trusell, Henrik, Andersson Sundell, Karolina
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4265334/
https://www.ncbi.nlm.nih.gov/pubmed/25475416
http://dx.doi.org/10.1186/s12913-014-0626-x
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author Trusell, Henrik
Andersson Sundell, Karolina
author_facet Trusell, Henrik
Andersson Sundell, Karolina
author_sort Trusell, Henrik
collection PubMed
description BACKGROUND: Several countries have introduced generic substitution, but few studies have assessed its effect on refill adherence. This study aimed to analyse whether generic substitution influences refill adherence to statin treatment. METHODS: Between 1 July 2006 and 30 June 2007, new users of simvastatin (n = 108,806) and atorvastatin (n = 7,464) were identified in the Swedish Prescribed Drug Register . The present study included atorvastatin users as an unexposed control group because atorvastatin was patent-protected and thus not substitutable. We assessed refill adherence using continuous measure of medication acquisition (CMA). To control for potential confounders, we used analysis of covariance (ANCOVA). Differences in CMA associated with generic substitution and generic substitution at first-time statin purchase were analysed. RESULTS: Nine of ten simvastatin users were exposed to generic substitution during the study period, and their adherence rate was higher than that of patients without substitution [84.6% (95% CI 83.5-85.6) versus 59.9% (95% CI 58.4-61.4), p < 0.001]. CMA was higher with increasing age (60–69 years 16.7%, p < 0.0001 and 70–79 years 17.8%, p < 0.0001, compared to 18–39 years) and secondary prevention (12.8%, p < 0.0001). CMA was lower among patients who were exposed to generic substitution upon initial purchase, compared to those who were exposed to a generic substitution subsequently [80.4% (95% CI 79.4-90.9) versus 89.8% (88.7-90.9), p < 0.001]. This difference decreased when those with only one statin purchase were excluded. CONCLUSIONS: Statin refill adherence was higher among patients who exposed to generic substitution compared to those who were not. Increasing age and previous cardiovascular disease affected refill adherence.
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spelling pubmed-42653342014-12-14 Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study Trusell, Henrik Andersson Sundell, Karolina BMC Health Serv Res Research Article BACKGROUND: Several countries have introduced generic substitution, but few studies have assessed its effect on refill adherence. This study aimed to analyse whether generic substitution influences refill adherence to statin treatment. METHODS: Between 1 July 2006 and 30 June 2007, new users of simvastatin (n = 108,806) and atorvastatin (n = 7,464) were identified in the Swedish Prescribed Drug Register . The present study included atorvastatin users as an unexposed control group because atorvastatin was patent-protected and thus not substitutable. We assessed refill adherence using continuous measure of medication acquisition (CMA). To control for potential confounders, we used analysis of covariance (ANCOVA). Differences in CMA associated with generic substitution and generic substitution at first-time statin purchase were analysed. RESULTS: Nine of ten simvastatin users were exposed to generic substitution during the study period, and their adherence rate was higher than that of patients without substitution [84.6% (95% CI 83.5-85.6) versus 59.9% (95% CI 58.4-61.4), p < 0.001]. CMA was higher with increasing age (60–69 years 16.7%, p < 0.0001 and 70–79 years 17.8%, p < 0.0001, compared to 18–39 years) and secondary prevention (12.8%, p < 0.0001). CMA was lower among patients who were exposed to generic substitution upon initial purchase, compared to those who were exposed to a generic substitution subsequently [80.4% (95% CI 79.4-90.9) versus 89.8% (88.7-90.9), p < 0.001]. This difference decreased when those with only one statin purchase were excluded. CONCLUSIONS: Statin refill adherence was higher among patients who exposed to generic substitution compared to those who were not. Increasing age and previous cardiovascular disease affected refill adherence. BioMed Central 2014-12-05 /pmc/articles/PMC4265334/ /pubmed/25475416 http://dx.doi.org/10.1186/s12913-014-0626-x Text en © Trusell and Andersson Sundell; licensee BioMed Central Ltd. 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Trusell, Henrik
Andersson Sundell, Karolina
Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study
title Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study
title_full Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study
title_fullStr Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study
title_full_unstemmed Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study
title_short Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study
title_sort effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4265334/
https://www.ncbi.nlm.nih.gov/pubmed/25475416
http://dx.doi.org/10.1186/s12913-014-0626-x
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