Bypass materials in vascular surgery

INTRODUCTION Arteriosclerotic changes can lead to circulatory disturbances in various areas of the human vascular system. In addition to pharmacological therapy and the management of risk factors (e. g. hypertension, diabetes, lipid metabolism disorders, and lifestyle), surgical interventions also play an important role in the treatment of arteriosclerosis. Long-segment arterial occlusions, in particular, can be treated successfully with bypass sur-gery. A number of different materials are available for this type of operation, such as autologous vein or pros-thetic grafts comprised of polytetrafluoroethylene (PTFE) or Dacron(®). Prosthetic materials are used especially in the treatment of peripheral artery disease, such as in aortoiliac or femoropopliteal bypass surgery. The present report will thus focus on this area in order to examine the effectiveness of different bypass materials. Among the efforts being made to refine the newly introduced DRG system in Germany, analysing the different bypass materials used in vascular surgery is particularly important. Indeed, in its current version the German DRG system does not distinguish between bypass materials in terms of reimbursement rates. Differences in cost structures are thus of especial interest to hospitals in their budget calculations, whereas both private and statutory health insurance funds are primarily interested in long-term results and their costs. OBJECTIVES The goal of this HTA is to compare the different bypass materials used in vascular surgery in terms of their medical efficiency and cost-effectiveness, as well as with regard to their ethical, social and legal implications. In addition, this report aims to point out the areas in which further medical, epidemiological and health economic research is still needed. METHODS Relevant publications were identified by means of a structured search of databases accessed through the German Institute of Medical Documentation and Information (DIMDI), as well as by a manual search. The for-mer included the following electronic resources: SOMED (SM78), Cochrane Library - Central (CCTR93), MEDLINE Alert (ME0A), MEDLINE (ME95), CATFILEplus (CATLINE) (CA66), ETHMED (ED93), GeroLit (GE79), HECLINET (HN69), AMED (CB85), CAB Abstracts (CV72), GLOBAL Health (AZ72), IPA (IA70), El-sevier BIOBASE (EB94), BIOSIS Previews (BA93), EMBASE (EM95), EMBASE Alert (EA08), SciSearch (IS90), Cochrane Library - CDSR (CDSR93), NHS-CRD-DARE (CDAR94), NHS-CRD-HTA (INAHTA), and NHS-EED (NHSEED). The present report included German and English literature published between the years 1999 and 2004. A list of the search parameters can be found in the appendix. No limits were placed on the target population, and the methodical quality of the included studies was determined using standardised checklists. RESULTS THE STUDIES INCLUDED IN THIS HEALTH TECHNOLOGY ASSESSMENT COMPARED THE FOLLOWING BYPASS MATERIALS: autologous vein, human umbilical vein (HUV) and synthetic materials such as PTFE or Dacron(®). Both the systematic reviews and the randomised controlled trials comparing autologous vein grafts to other bypass materials come to the conclusion that autologous vein is superior to all other materials. From a medical viewpoint, there are no clear differences between the various synthetic materials. To date, the subject of bypass materials in vascular surgery has not been addressed comprehensively from an economic point of view. Indeed, we were able to identify only one publication that compared the cost of various bypass materials. The remaining health economic studies did not compare costs, cost effectiveness, or quality of life associated with the use of various bypass materials. DISCUSSION When deciding which bypass material to use, vascular surgeons take a number of medical considerations into account, including the bypass area, the availability of autologous vein, the amount of operation time available, and the health status of the patient. The studies included in this health technology assessment demonstrate that autologous vein is usually the preferred material for bypass grafts. In contrast, comparisons of various synthetic materials did not show any specific differences. It remains to be seen whether studies on newly developed synthetic materials will show these to have any particular advantages. The randomised controlled trials included in the present report were limited by a number of methodological weaknesses, such as different methods for determining patency rates, sample size and power problems, the interpretation of non-significant results, and a lack of consideration of additional factors. From an economic point of view, there is still great need for further research, and we have attempted to describe a number of pressing questions for health economic studies in the present report.