Economic evaluation of standard heparin and enoxaparin for prophylaxis against deep vein thrombosis in elective hip surgery
Drummond M, Aristides M, Davies L, Forbes C
Record Status
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.
Health technology
Prophylaxis against deep vein thrombosis (DVT) in elective hip surgery using either heparin or enoxaparin (a form of low molecular weight heparin).
Type of intervention
Secondary prevention.
Economic study type
Cost-effectiveness analysis.
Study population
Patients undergoing prophylaxis against DVT in elective hip surgery.
Setting
Hospital. The economic study received input from York University and Dundee University (UK) and Canberra (Australia).
Dates to which data relate
Effectiveness data was taken from studies published between 1987 and 1992.1989-1990 prices were used.
Source of effectiveness data
Review of previously completed studies.
Modelling
A decision tree was used to set out the range of clinical alternatives and the probabilities of clinical events.
Outcomes assessed in the review
Rate of DVT with prophylaxis and rate of subsequent pulmonary embolism.
Study designs and other criteria for inclusion in the review
Clinical trials comparing enoxaparin with standard heparin in patients undergoing hip replacement.
Sources searched to identify primary studies
Not stated.
Criteria used to ensure the validity of primary studies
Not stated.
Methods used to judge relevance and validity, and for extracting data
Not stated.
Number of primary studies included
One randomized trial.
Results of the review
The probability of the patient having DVT was 0.125 for enoxaparin and 0.25 for standard heparin.
Measure of benefits used in the economic analysis
Rate of DVT, pulmonary embolism and mortality.
Direct costs
Direct health service costs included were: cost of drugs, drug administration, standard blood tests, cost of confirming clinical diagnosis, nursing and physician time, hotel costs and intensive care costs.
Currency
UK pounds sterling ().
Sensitivity analysis
A sensitivity analysis was performed varying key parameters (cost of drug administration and probability of false clinical diagnosis of DVT or pulmonary embolism).
Estimated benefits used in the economic analysis
Probability of DVT was 0.125 for enoxaparin and 0.25 for standard heparin. Death rate was 0.5% and 0.9% respectively. This was robust to sensitivity analysis.
Cost results
The cost of enoxaparin prophylaxis was estimated at 104 per patient and that of standard heparin prophylaxis at 124 per patient.
Synthesis of costs and benefits
Enoxaparin prophylaxis was the dominant strategy, with an overall saving of 20 per patient.
Authors' conclusions
Enoxaparin was found to be more cost-effective than standard heparin in the prophylaxis of DVT, its higher cost being offset by savings in other hospital resources.
CRD Commentary
More information on the authors' search strategy would have been desirable as the reader was unable to evaluate whether the search for primary studies was comprehensive. Thus it was not clear that estimates of reduction in DVT were reliable. Direct health service quantities/costs were adequately measured. A good sensitivity analysis was carried out, including meta-analysis values of one of the variables.
Source of funding
Grant from Rhone-Poulenc Rorer.
Bibliographic details
Drummond M, Aristides M, Davies L, Forbes C. Economic evaluation of standard heparin and enoxaparin for prophylaxis against deep vein thrombosis in elective hip surgery. British Journal of Surgery 1994; 81(12): 1742-1746