Cost comparison analysis: pentaerythrithyl tetranitrate (PETN) and isosorbide dinitrate (ISDN) prescribed to diabetic patients in primary care practices in Germany

Abstract

Both pentaerythrithyltetranitrate (Pentalong, PETN) and isosorbide dinitrate (ISDN) are commonly used in the therapy of ischemic heart disease (IHD). However, little is known about the therapeutic patterns in diabetic patients and no comparative data are available regarding the prescription costs of these two substances. Thus, the aim of this investigation was to compare the costs for PETN and ISDN therapy in diabetic patients in primary care. All continuously treated patients aged > or = 40 years with diabetes (anti-diabetic agents) and IHD or angina pectoris (ICD codes) and newly started on PETN or ISDN therapy (index date) in the period 2000-2005 were selected from a database containing data from 400 practices throughout Germany (Disease Analyzer, IMS Health). Prescriptions costs for PETN and ISDN, as well as costs for cardiovascular comedication, were determined for the period 183 days before and after the index date, and that changes in costs after the index date were calculated. Differences in costs between the two groups were evaluated using multivariate regression, adjusting for age, sex and comorbidity. Patients in Eastern (n = 137, age 71 +/- 10 years, 55% male) and Western Germany (n = 212, age 73 +/- 9 years, 50% male) were analyzed separately since there is a longer history of PETN use in Eastern Germany. Significantly more patients were treated with PETN in Eastern Germany (61 vs. 11%, p < 0.05). The patient groups treated with PETN and ISDN differed with respect to sex and comorbidity. PETN therapy was more expensive than ISDN therapy in both German regions (adjusted cost differences were 10 and 17 Euro). However, when comedication was taken into account, a smaller cost increase after the index date was observed in the PETN group than in the ISDN group (non-significant cost savings of 43 and 52 Euro after adjustment for Western and Eastern Germany, respectively). PETN therapy tends to produce a saving in costs compared to ISDN therapy in diabetic patients when costs for comedication are taken into account and after adjustment for age and comorbidity. The prescription patterns in Eastern and Western Germany and the patient characteristics of those receiving PETN and ISDN differed, indicating differences in patients selection and prescribing by physicians in the two regions.