ORIGINAL REPORT Influence of the use of functional foods enriched with phytosterols/‐stanols on adherence to statin therapy Simone R. B. M. Eussen 1,2 , Marcel L. Bouvy 1 , Cathy J. M. Rompelberg 2 , Menno E. van der Elst 3 , Johan Garssen 1 , Marco H. Oosterveld 4 , Anthonius de Boer 1 , Johan J. de Gier 5 , Henk J. van Kranen 2 and Olaf H. Klungel 1 * 1 Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands 2 National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands 3 Medicines Evaluation Board, The Hague, The Netherlands 4 Waldeck Pharmacy, The Hague, The Netherlands 5 Department of Pharmacotherapy and Pharmaceutical Care, University of Groningen, Groningen, The Netherlands ABSTRACT Purpose Subjects using functional foods with approved health claims may be more likely to be non‐adherent with prescribed drug therapy. This study aimed to assess the influence of the use of phytosterol/‐stanol‐enriched functional foods on adherence to statin therapy among patients initiating treatment. Methods We used data from the statin intervention research project, a randomized controlled trial aimed at improving adherence to statins. In the trial, new statin users were randomized to receive either usual care or extensive pharmaceutical care consisting of five individual counseling sessions. Customary use of phytosterol/‐stanol‐enriched products was identified by questionnaires filled out by all participants. Automated pharmacy‐dispensing records were used to assess adherence in terms of discontinuation of therapy and the medication possession ratio. Analyses were performed for the overall population, as well as stratified for receiving pharmaceutical or usual care. Results The use of functional foods enriched with phytosterols/‐stanols was not related to discontinuation of statin therapy, neither in the overall population (overall population adjusted hazard rate ratio (HR adj ): 0.80 [95%CI: 0.59 –1.08]), nor when stratified by randomization arm (pharmaceutical care HR adj : 0.77 [95%CI: 0.49– 1.23]); usual care HR adj : 0.81 [95%CI: 0.54 –1.21]). The median medication possession ratio was significantly lower in users of phytosterols/‐stanols in the usual care group, but the difference was not clinically relevant. Conclusions Customary use of phytosterol/‐stanol‐enriched functional foods did not affect adherence to statins in new users that are well informed on the beneficial effects of statin therapy. In daily medical practice, general practitioners and pharmacists should urge subjects not to take phytosterol/‐stanol‐enriched functional foods as replacement for their prescribed medication. Copyright © 2011 John Wiley & Sons, Ltd. key words—lipid‐lowering treatment; adherence; statins; phytosterols/‐stanols Received 10 January 2011; Revised 4 March 2011; Accepted 14 April 2011 INTRODUCTION Coronary heart disease (CHD) is among the leading causes of death worldwide. Abnormal blood lipid levels are one of the main risk factors for CHD. 1 The 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibitors (statins) lower total and low density lipoprotein (LDL) cholesterol by inhibiting cholesterol synthesis 2 and have been shown to reduce the 5‐year incidence of major coronary events by about one‐ third. 3 In recent years, functional foods enriched with phytosterols or phytostanols, claimed to lower cho- lesterol levels, have gained huge popularity. 4 It is therefore conceivable that an increasing number of people will combine their statin therapy with phytosterol/‐stanol‐enriched products. In several ran- domized controlled trials (RCTs) positive additive effects of phytosterols/‐stanols on the cholesterol‐ lowering effect of statins have been demonstrated (for review, see Scholle et al., 2009). 5 Phytosterols or phytostanols are thought to further reduce LDL *Correspondence to: O. H. Klungel, Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, P.O. Box 80082, 3508 TB Utrecht, The Netherlands. E‐mail: O.H.Klungel@uu.nl Copyright © 2011 John Wiley & Sons, Ltd. pharmacoepidemiology and drug safety 2011; 20: 830 – 837 Published online 7 June 2011 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/pds.2168