Determinants of persistence in hypertensive patients treated with irbesartan: results of a postmarketing survey

Abstract

Background: Persistence is a key factor for long-term blood pressure control, which is of high prognostic importance for patients at increased cardiovascular risk. Here we present the results of a post-marketing survey including 4769 hypertensive patients treated with irbesartan in 886 general practices in Switzerland. The goal of this survey was to evaluate the tolerance and the blood pressure lowering effect of irbesartan as well as the factors affecting persistence in a large unselected population.

Methods: Prospective observational survey conducted in general practices in all regions of Switzerland. Previously untreated and uncontrolled pre-treated patients were started with a daily dose of 150 mg irbesartan and followed up to 6 months.

Results: After an observation time slightly exceeding 4 months, the average reduction in systolic and diastolic blood pressure was 20 (95% confidence interval (CI) -19.6 to -20.7 mmHg) and 12 mmHg (95% CI -11.4 to -12.1 mmHg), respectively. At this time, 26% of patients had a blood pressure < 140/90 mmHg and 60% had a diastolic blood pressure < 90 mmHg. The drug was well tolerated with an incidence of adverse events (dizziness, headaches,...) of 8.0%. In this survey more than 80% of patients were still on irbesartan at 4 month. The most important factors predictive of persistence were the tolerability profile and the ability to achieve a blood pressure target < or = 140/90 mmHg before visit 2. Patients who switched from a fixed combination treatment tended to discontinue irbesartan more often whereas those who abandoned the previous treatment because of cough (a class side effect of ACE-Inhibitors) were more persistent with irbesartan.

Conclusion: The results of this survey confirm that irbesartan is effective, well tolerated and well accepted by patients, as indicated by the good persistence. This post-marketing survey also emphasizes the importance of the tolerability profile and of achieving an early control of blood pressure as positive predictors of persistence.

Figure 1

Patient population and available data. Summary of the analysis patient populations of this investigation and of the data available for analysis.

Figure 2

a. Evolution of blood pressure during observation period (~4 months): Efficacy Sample. Baseline SBP (systolic blood pressure): previously untreated patients 168.8 mmHg, pre-treated 163.5 mmHg (*p < 0.0001); SBP at last visit: previously untreated 142.8 mmHg, pre-treated 146.9 mmHg (p < 0.0001). Baseline DBP (diastolic blood pressure): previously untreated patients 101.2 mmHg, pre-treated 96.3 mmHg (*p < 0.0001); DBP at last visit: previously untreated 85.9 mmHg, pre-treated 86.8 mmHg (p = 0.004). b. Reaching of therapeutic targets: Efficacy Sample. Response to treatment is defined as reaching DBP < 90 mmHg or a reduction of DBP = 10 mmHg. In real-life practice, a satisfactory objective is also the normalization of DBP (< 90 mmHg). Target = 140/90 mmHg was introduced because of digit preference of study GPs (see results).

Figure 3

Ongoing treatment and discontinuation reasons: Efficacy Sample. (n = 4639)Other reasons included: patient moved, blood pressure normalized, break off attempt, concurrent disease, effect too strong, lost to follow up and others. Multiple answers were possible.

Figure 4

Mean (line) and 95% confidence interval (box) for the odds ratio (OR) of the main variables correlating significantly with ongoing treatment or discontinuation in a logistic regression model; Efficacy Sample. For detailed explanations see results.

Figure 5

Self-reported compliance according to the patient for selected patient subgroups. Good compliance with treatment after 1 year; Compliance Form Patient (n = 853). Good compliance is defined as >80% adherence to the prescribed therapeutic regimen. In this case it means irbesartan intake on 6 or 7 days a week, as reported by the patients. Risk = WHO risk categories; ISH = isolated systolic hypertension; constant mono-and polytherapy; on & off = on and off treatment breaks; * = p < 0.05 compared to the rest of the patients.