Medication adherence and persistence according to different antihypertensive drug classes: A retrospective cohort study of 255,500 patients.

BACKGROUND: Suboptimal adherence to antihypertensives leads to adverse clinical outcomes. This study aims to determine and compare medication adherence and persistence to different first-line antihypertensive drug classes in a large cohort. METHODS: A cohort study was performed using claims data for prescriptions in the German statutory health insurance scheme that insures approximately 90% of the population. A total of 255,500 patients with a first prescription of an antihypertensive were included and followed for 24months. Persistence was determined based on gaps in continuous dispensation. Adherence was analyzed by calculating the medication possession ratio (MPR). RESULTS: Within a 2-year period, 79.3% of all incident users of antihypertensive monotherapy met the classification of non-persistence (gap >0.5 times the number of days supplied with medication) and 56.3% of non-adherence (MPR<0.8). Beta-blockers (42.5%) and angiotensin-converting enzyme inhibitors (31.9%) were the most widely prescribed drug classes. Non-persistence and non-adherence were highest for diuretics (85.4%, n=6149 and 66.3%, n=4774) and lowest for beta-blockers (77.6%, n=76,729 and 55.2%, n=54,559). The first gap of antihypertensive medication occurred in median 160-250days after initiation, and the average medication possession ratio for all drug classes was less than 0.8. Fixed combinations with diuretics showed a 19.8% lower chance for non-adherence (OR=0.802, 99.9% CI=[0.715-0.900], p<0.001) and an 8.4% lower hazard for non-persistence (HR 0.916, 99.9% CI=[0.863-0.973], p<0.001) compared with monotherapies. CONCLUSIONS: This large cohort study reveals important differences in 2-year adherence and persistence between antihypertensives that were lowest for diuretics. Fixed-dose combinations with diuretics may facilitate adherence compared to single substance products. However, effective strategies to improve adherence to antihypertensives are needed regardless of drug class.

Adherence to antihypertensives: feasibility of two self-report instruments to investigate medication-taking behaviour in German community pharmacies.

OBJECTIVE: To design and test the feasibility of two questionnaires in German community pharmacies exploring self-reported adherence to antihypertensives. METHODS: Two self-report questionnaires were designed for patients treated with antihypertensives. The 29-item-questionnaire (long form, LF) was completed by pharmacists interviewing patients who were on the premises filling a prescription. The short form (SF; 19 items) was sent by pharmacies to patients via mail. The acceptance of the instruments by patients and pharmacists as well as the feasibility to measure medication-taking behaviour was investigated. Adherence was investigated by using a modified 5-(LF) or 6-item (SF) Morisky score. RESULTS: Of 44 community pharmacies contacted, 18 agreed to participate. Patients' response rates were 428/915 (46.8%) for the SF and 249/760 (32.8%) for the LF. One hundred and seventy-nine patients (41.8%) and 70 patients (28.1%) reported adherence problems according to the SF and LF respectively. CONCLUSIONS: To our knowledge, this is the first attempt to develop a self-report instrument for the detection of non-adherence in patients taking antihypertensives in this setting in Germany. Patients were willing to provide detailed information about their medication-taking behaviour. Underestimation of non-adherence may be more pronounced when applying the questionnaire in the pharmacy.

Treatment duration (persistence) of basal insulin supported oral therapy (BOT) in Type-2 diabetic patients: comparison of insulin glargine with NPH insulin.

OBJECTIVE: To compare the persistence (treatment duration) of basal insulin supported oral therapy (BOT) using insulin glargine (GLA) or NPH insulin (NPH) in Type-2 diabetic patients. METHODS: This retrospective cohort study reports results from an analysis of claims data from prescriptions for ambulatory patients within the German Statutory Health Insurance scheme. The study is based on claims data from more than 80% of German community pharmacies. Treatment duration until switching to a basal bolus treatment regimen (intensified conventional insulin therapy: ICT) was determined in insulin-naïve patients who began treatment with BOT using GLA or NPH between 01/2003 and 12/2006. RESULTS: A total of 97,998 patients (61,070 GLA and 36,928 NPH) were included. Within the observation period, 23.5% of GLA patients and 28.0% of NPH patients switched from BOT to ICT. The upper quartile of probability of continuation of therapy (the 75th percentile) was reached after 769 days in GLA patients and after 517 days in NPH patients. Therefore, the risk of switching to ICT was significantly higher with NPH compared to GLA: hazard ratios were 1.34 (99% CI: 1.29-1.38; unadjusted) and 1.22 (99% CI: 1.18-1.27) after adjustment for predefined covariates. Various sensitivity analyses using modified inclusion criteria and endpoint definitions were applied and these confirmed the initial results. CONCLUSION: Type-2 diabetic patients under BOT with GLA stayed significantly longer on the initial therapy before switching to ICT than patients on BOT using NPH.

Generic switch after ramipril patent expiry is not associated with decreased pharmacy refill compliance: a retrospective study using the DAPI database.

OBJECTIVE: For treatment success in chronic diseases such as hypertension, adequate adherence to long-term pharmacotherapy is a prerequisite. The purpose of this study was to evaluate whether switching from brand name ramipril to a generic product after patent expiry may negatively affect patients' refill compliance. METHODS: Claims data for ambulatory prescriptions within the statutory health insurance system were evaluated. Patients were included if they had filled a ramipril prescription (index) for either brand name or generic ramipril products between September 2003 and June 2004. Patients had to be continuously treated with ramipril for at least 12 months before and after the index date. Patients with a change from brand name to generic product or vice versa during follow-up after the index date were excluded from the analyses, as were patients who could not be unequivocally allocated to characteristics of covariates. Refill compliance was analysed by calculating the medication possession ratio (MPR), assuming that patients were prescribed one unit dose per day (MPR(UD)). RESULTS: In total, 142,690 and 79,191 patients were classified as brand name or generic therapy, respectively. Median MPR(UD) values were 0.95 and 0.96 (P < 0.001). In a logistic regression model adjusting for covariates, the probability for noncompliance (MPR(UD) < 0.8) was marginally lower in the generic compared with the brand name group (odds ratio 0.926, 99% confidence interval 0.901-0.951, P < 0.001). CONCLUSION: These results suggest that refill compliance is not negatively affected by a physician-induced switch from brand name to generic ramipril products after patent expiry.