Disclosures A.L., SH.O. and V.C.M. are employees of Novartis Pharma AG, Basel, Switzerland, and are therefore eligible for Novartis stock and stock options. B.V. and E.P.T. are employees of AARDEX Ltd. J.U. is a shareholder of AARDEX Ltd and acts, unpaid, as Chief Scientist of AARDEX Ltd. M.B. has received research grants and has been a speaker for Novartis Pharma AG and AARDEX Ltd.
Effects on blood pressure and cardiovascular risk of variations in patients’ adherence to prescribed antihypertensive drugs: role of duration of drug action
Version of Record online: 22 NOV 2010
© 2010 Blackwell Publishing Ltd
International Journal of Clinical Practice
Volume 65, Issue 1, pages 41–53, January 2011
How to Cite
Lowy, A., Munk, V. C., Ong, S. H., Burnier, M., Vrijens, B., Tousset, E. P. and Urquhart, J. (2011), Effects on blood pressure and cardiovascular risk of variations in patients’ adherence to prescribed antihypertensive drugs: role of duration of drug action. International Journal of Clinical Practice, 65: 41–53. doi: 10.1111/j.1742-1241.2010.02569.x
- Issue online: 13 DEC 2010
- Version of Record online: 22 NOV 2010
- Paper received July 2010, accepted November 2010
Aim: To determine the effects of imperfect adherence (i.e. occasionally missing prescribed doses), and the influence of rate of loss of antihypertensive effect during treatment interruption, on the predicted clinical effectiveness of antihypertensive drugs in reducing mean systolic blood pressure (SBP) and cardiovascular disease (CVD) risk.
Method: The effects of imperfect adherence to antihypertensive treatment regimens were estimated using published patterns of missed doses, and taking into account the rate of loss of antihypertensive effect when doses are missed (loss of BP reduction in mmHg/day; the off-rate), which varies between drugs. Outcome measures were the predicted mean SBP reduction and CVD risk, determined from the Framingham Risk Equation for CVD.
Results: In patients taking 75% of prescribed doses (typical of clinical practice), only long-acting drugs with an off-rate of ∼1 mmHg/day were predicted to maintain almost the full mean SBP-lowering effect throughout the modelled period. In such patients, using shorter-acting drugs (e.g. an off-rate of ∼5–6 mmHg/day) was predicted to lead to a clinically relevant loss of mean SBP reduction of > 2 mmHg. This change also influenced the predicted CVD risk reduction; in patients with a baseline 10-year CVD risk of 27.0% and who were taking 75% of prescribed doses, a difference in off-rate from 1 to 5 mmHg/day led to a predicted 0.5% absolute increase in 10-year CVD risk.
Conclusions: In patients who occasionally miss doses of antihypertensives, modest differences in the rate of loss of antihypertensive effect following treatment interruption may have a clinically relevant impact on SBP reduction and CVD risk. While clinicians must make every effort to counsel and encourage each of their patients to adhere to their prescribed medication, it may also be prudent to prescribe drugs with a low off-rate to mitigate the potential consequences of missing doses.