Switching from a brand-name statin to a generic statin has been shown to improve adherence, researchers in Sweden report [1].
Henrik Trussel and Andersson Sundell of the Sahlgrenska Academy at the University of Gothenburg assessed the effects of generics substitution on refill adherence to statin therapy. Generics substitution of statins has been introduced in many countries, but whether substitution affects refill adherence has not been studied. There have been reports that adherence drops following a switch to generics in general, attributed to patients finding it difficult to keep track of their medicine [2]. Other studies found that adherence is highest among patients that start treatment on generics, compared with those who switch from brand-name drugs.
Trussel and Sundell calculated refill adherence to statin therapy using continuous measure of medication acquisition (CMA): the number of days’ supply dispensed during the study period divided by the number of days in the study period. This was a nationwide population-based study.
Their study population comprised 116,270 patients from the Swedish Prescribed Drug Register, 108,806 of whom were new users of simvastatin and 7,464 of whom were new users of atorvastatin. The study included atorvastatin users as an unexposed control group because atorvastatin was patent-protected and therefore not substitutable.
For simvastatin, the mean CMA was 84.3%. For atorvastatin, the mean CMA was 79.0%. Most simvastatin users were exposed to generics substitution during follow-up (92.8%). The adjusted mean value of CMA was significantly lower (36.7%) for all individuals who were not exposed to generics substitution during follow-up. Refill adherence was significantly lower among simvastatin users who actively refused generics substitution.
Changes in adherence were also linked to the timing of generics substitution. The CMA was lower for patients exposed to generics from the start, compared with users who had been switched to a generic from a brand-name drug. Among those who had switched, the CMA was significantly higher among older individuals. The CMA was also significantly high among patients previously diagnosed with cardiovascular disease, those with oral antidiabetic medicines and individuals taking at least five different medications.
The study fills an important gap in the understanding of generics substitution on refill adherence to statin therapy. Statin refill adherence was found to be higher among patients exposed to generics substitution compared with those who were not. Switching from the blockbuster cholesterol-lowering drug Lipitor to generic atorvastatin saved the UK’s National Health Service (NHS) more than GBP 350 million in the first 12 months following the expiration of Pfizer’s patent exclusivity [3].
Conflict of interest
The authors of the research paper [1] declared that there were no conflicts of interest.
Editor’s comment
Readers interested to learn more about increasing generics usage are invited to visit www.gabi-journal.net to view the following manuscripts published in GaBI Journal:
Payers endorse generics to enhance prescribing efficiency: impact and future implications, a case history approach
European payer initiatives to reduce prescribing costs through use of generics
Readers interested in contributing a research paper to GaBI Journal – an independent, peer reviewed academic journal platform – please send us your submission here.
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References
1. Trussel H, Andersson Sundell K, Effects of generic substitution on refill adherence to statin therapy: a nationwide population-based study. BMC Health Serv Res. 2014;14(1):626.
2. GaBI Online - Generics and Biosimilars Initiative. Generic substitution causing confusion [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 May 8]. Available from: www.gabionline.net/Generics/Research/Generic-substitution-causing-confusion
3. GaBI Online - Generics and Biosimilars Initiative. Lipitor generics saved UK NHS £350 million in first 12 months [www.gabionline.net]. Mol, Belgium: Pro Pharma Communications International; [cited 2015 May 8]. Available from: www.gabionline.net/Generics/General/Lipitor-generics-saved-UK-NHS-350-million-in-first-12-months
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