Adherence to prescribed drugs is the most discussed component of patient compliance. Low adherence rates are often cited as the primary cause of poor blood pressure control and hypertension. As with diagnostic compliance, rates of treatment nonadherence vary, although 50% is frequently cited, which we concluded was a reasonable estimate.
Basis
Understanding the details of hypertension prevalence, patient compliance, and success rates is never simple. Thus, we opted to share aspects of our decision-making process and our basis for selecting 50% drug adherence. The process included reviews of the literature including a recent AHA-Circulation Research study in which the authors acknowledged that “…recent data suggest that even in clinical trials nonadherence can affect a substantial percentage of the participants.[1]“
The degree of drug adherence correlates strongly with
the number of prescribed pills and the number of times they are taken each day.
Simpler drug regimens with fewer drugs correlate with improved adherence.
The same article asserts that in the U.S., “the large improvement in hypertension control over time coincides with a greater number of antihypertensive medications prescribed per patient.” It then acknowledges that:
“Complex regimens with multiple medications, especially when paired with multiple daily doses, are long-recognized as barriers to adherence. Alternatively, fewer medications, and especially fewer pills, which can be implemented using once-daily single-pill combinations are consistently associated with better adherence and hypertension control. Patients who reach therapeutic targets more rapidly, who require fewer adjustments in their medication regimen, and who experience no or limited adverse effects are more likely to adhere than patients with a longer period to control, who often undergo multiple changes to their medication regimens, and experience adverse effects, are less likely to adhere to treatment.[2]”
A more recent post on the American Medical Association website identified “8 reasons why patients don’t take their medications.” The list included fear, costs, and having to take too many pills. It also cited research “showing that patients don’t take their medications as prescribed about half the time.[3]” An article published in the Centers for Disease Control and Prevention’s (CDC) Prevent Chronic Disease page that focused on people ages 35 to 64 with employer-sponsored health insurance concluded that “Only 40% to 74% of patients treated for hypertension take medications as prescribed.[4]”
Conclusion
We found multiple estimates of drug adherence to hypertension treatments in published studies. After reviewing the literature and further discussions with clinicians, we selected 50% adherence as a reasonable, well-supported input into our models and calculations.
References
[1] Michel Burnier and Brent M. Egan, Adherence in Hypertension: A Review of Prevalence, Risk Factors, Impact, and Management, March 28, 2019, Circulation Research, https://doi.org/10.1161/CIRCRESAHA.118.313220 [2] Ibid, Burnier [3] 8 reasons patients don't take their medications, February 22, 2023, American Medical Association, https://www.ama-assn.org/delivering-care/patient-support-advocacy/8-reasons-patients-dont-take-their-medications [4] Baker-Goering MM, Roy K, Howard DH. Relationship Between Adherence to Antihypertensive Medication Regimen and Out-of-Pocket Costs Among People Aged 35 to 64 With Employer-Sponsored Health Insurance. Prev Chronic Dis 2019;16:180381. DOI: http://dx.doi.org/10.5888/pcd16.180381