Studies have found that patients receiving fixed-dose combination pills are more likely to reach their target BP, physicians are more satisfied with their ability to manage hypertension, and adverse effects are either similar or less with the fixed-dose therapies compared with monotherapies.15,16
Studies of adherence patterns among patients treated with fixed-dose combinations of antihypertensive agents vs separate antihypertensive agents demonstrate increased adherence among patients treated with fixed-dose combinations.17-21 In a clinical trial involving 4146 participants who were treated with a fixed dose of amlodipine and atorvastatin or separate pills, 33% of patients in the fixed-dose cohort had ceased treatment by 12 months compared with 59% of patients who were taking the 2-pill regimen (HR, 2.17; 95% CI, 2.05–2.13; P < .0001), resulting in a 117% higher rate of nonadherence in the 2-pill regimen. The median persistence time (ie, time to discontinuation with medication) was 8 months with the 2-pill regimen, but 37 months or longer with the fixed-dose combination.21
A meta-analysis of 9 studies found that fixed-dose combinations reduced the risk of nonadherence by 26% compared with single-pill combination therapy.22
One downside to fixed-dose therapy is cost. Out-of-pocket costs are a significant barrier to medication adherence and most fixed-dose options are branded drugs that generally require higher copayments or coinsurance vs generic single-pill drugs that may have copayments as low as $4.6
Other opportunities to improve adherence to antihypertensive medications
Other evidence-based opportunities to improve adherence to antihypertensive medications include improved relationships with, and communication from, health care providers, given that patients often do not understand their disease and recommended treatments.23,24
Interviews with 826 patients with hypertension found that although 90% knew that lowering their BP would improve their health and 91% reported that a health care provider had told them that they had hypertension or high BP, 41% did not know their BP level. In addition, just 34% of patients with hypertension identified systolic BP (SBP) as the “top” number of their reading and only 32% identified diastolic BP (DBP) as the “bottom” number. Finally, only one-third of patients were able to identify both SBP and DBP, and one-quarter of them did not know the optimal level for either.25
Other provider interventions that have resulted in improved adherence include changing medication to reduce or avoid adverse effects, simplifying dosing (as described earlier), and switching to less-expensive drugs if cost is an issue. Nurses and pharmacists are also important members of the team when it comes to improving adherence and reinforcing education.24
Home blood pressure monitoring
Another reason for nonadherence is that patients may not believe they need treatment since hypertension rarely manifests with symptoms. Furthermore, patients may not perceive that the medication they take has any effect because they did not have symptoms to begin with. Home BP monitoring (HBPM), or self BP monitoring, is one tool for improving adherence, possibly by providing immediate feedback to patients on how well their BP is controlled.26 Many major medical societies recommend HBPM as part of any hypertension management strategy.27-30
Patients who use HBPM can avoid many limitations associated with office BP monitoring (OBPM), including poor measurement techniques, infrequent measurement, white coat hypertension, and masked hypertension. Patients can also avoid reverse white coat hypertension, where OBPM is normal although out-of-office BP is high.28 Patients should take 3 readings at 1-minute intervals, usually in the morning and evening. The weekly average of these readings is their home BP (normotension is defined as an average BP <135/85 mm Hg).31 Typically, the HBPM monitoring is more accurate in identifying risk than OBPM when there are discrepancies between them.28 It is good practice to instruct patients utilizing HBPM to bring their home BP device to the office for a comparison.
There is some evidence that HBPM may contribute to improved adherence. A systematic review of 11 randomized controlled trials found that in 6 trials the use of HBPM resulted in improved medication adherence, although in 5 of those studies additional interventions were used. These interventions included patient counseling about adverse effects of the medication, timepiece caps that reminded patients to take their medication, tips to enhance adherence, and reinforcement of positive behavior by nurses, pharmacists, lay health workers, or a telephonic system.32 This illustrates an important point in adherence interventions: more is better, and it usually takes a combination of approaches to improve adherence.33,34
The only trial in the review that demonstrated that HBPM alone improved adherence randomized 628 patients to either HBPM or usual care for 6 weeks. The groups had similar compliance rates at baseline, and both demonstrated less adherence at the end of the 6-week trial. However, patients who measured their BP at home still demonstrated greater compliance than those receiving usual care (P < .05).35