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Decision-analysis of transjugular intrahepatic portosystemic shunt versus distal splenorenal shunt for portal hypertension |
Zacks S L, Sandler R S, Biddle A K, Mauro M A, Brown R S |
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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 Transjugular intrahepatic portosystemic shunt (TIPS) for portal hypertension in patients with Child's Class A cirrhosis.
Economic study type Cost-effectiveness analysis.
Study population Hypothetical patients with Child's class A cirrhosis with complications of portal hypertension, receiving either TIPS or DSRS and followed over 2 years.
Setting Secondary care. The economic study was conducted in the USA.
Dates to which data relate A MEDLINE search of relevant articles published between 1966 and 1997 was conducted, but, due to the relative novelty of DSRS only results from articles published in the last 10 years were used. Costs data were collected between 1995 and 1996 and expressed in 1996 US dollars.
Source of effectiveness data Effectiveness data were derived from a review of previously published studies and estimates of effectiveness.
Modelling A deterministic decision analytic model, restricted to two years of follow-up, was used to derive the costs and benefits of the two interventions.
Outcomes assessed in the review The outcomes assessed in the review were the probabilities associated with the TIPS and DSRS procedures, including successful stenting, procedure death, dysfunction of TIPS, dysfunction of DSRS and death from liver disease in each year of the model (1 and 2).
Study designs and other criteria for inclusion in the review There were no randomised control trials comparing TIPS with DSRS, so the study designs considered are various: case studies, statistics. Studies identified through a MEDLINE search, using the following keywords, were included in the review: TIPS, transjugular intrahepatic portosystemic shunt, portosystemic shunt and distal splenoral shunt. Articles recommended in the bibliographies of the above papers were also included in the review, as well as references supplied by the Department of Surgery, University of North Carolina.
Sources searched to identify primary studies A MEDLINE literature search to identify articles that described long-term follow-up of patients undergoing TIPS and DSRS was undertaken. Articles recommended in the bibliographies of the above papers were also included in the review, as well as references supplied by the Department of Surgery, University of North Carolina.
Criteria used to ensure the validity of primary studies Not stated. However, due to the relative novelty of DSRS only results from articles published in the last 10 years were used.
Methods used to judge relevance and validity, and for extracting data The criteria used to judge relevance seemed to be the presence of search words and year of publication. Summary statistics from each study considered were used.
Number of primary studies included 21 studies were used in the derivation of input probabilities for the model.
Methods of combining primary studies Where more than one study was used to derive estimates, data pooling was used. Ranges for the majority of base-case estimates were provided.
Investigation of differences between primary studies Not stated, although sensitivity analyses were applied to the parameters used in the model.
Results of the review Input TIPS variables were probabilities of:
successful stenting (0.99),
death from tips procedure (0.01),
death in year 1 (0.06),
death in year 2 (0.11),
stent patency in those alive in year 1 (0.52),
primary patency in year 2- cumulative (0.32),
requiring new stent at revision (0.56),
patency at end of year 1 after revision of new stent (0.96),
patency at the end of year 1after revision without new stent (0.83),
patency at the end of year 2 after revision with new stent-cumulative (0.90),
patency at the end of year 2 after revision without new stent-cumulative (0.79).
DSRS input variables were probabilities of:
postoperative death (0.02),
shunt occlusion in year 1 (0.03),
death in year 1 (0.03)
and death in year 2(0.12).
Methods used to derive estimates of effectiveness Where input variables for the model were not available in the literature the authors included their own estimates.
Estimates of effectiveness and key assumptions Survival time (months) was estimated to be 1 for procedure-related death (DSRS or TIPS), 6 for death at one year from liver disease (DSRS or TIPS), 18 for death at 2 years from liver disease (DSRS or TIPS), 6 for first revision of TIPS in year 1, 9 for second revision of TIPS in year 1 and 18 for revision of TIPS in year 2.
Measure of benefits used in the economic analysis The benefit measure was life-years saved.
Direct costs The perspective of the payer was used and only direct costs were considered. TIPS costs considered were admission for initial placement of TIPS or revision requiring new stent, admission for revision of TIPS without requiring new stent, and ultrasound with Doppler. DSRS costs included admission for DSRS surgery, angiogram, splenectomy and gastric devascularisation. Hospital charge data were obtained from the University of North Carolina Hospitals (UNCH). Using the relevant ICD-9-CM codes, the authors identified patients who had a TIPS or DSRS between July 1995 and June 1996 at the UNCH. Standardised costs were derived from charges using the Health Care Financing Agency (HCFA) cost-to-charge ratio and were expressed in 1996 US$. Discounting was applied at a 3% annual rate.
Statistical analysis of costs Sensitivity analysis In order to account for variability in the data, key variables used in the model were modified in a series of two-way sensitivity analyses.
Estimated benefits used in the economic analysis Life-years saved were as follows: 1.96 for TIPS and 1.86 for DSRS (with 1.96 and 1.84 respectively for a 3% discount rate).
Cost results Patients who underwent TIPS incurred $41,685 in costs, compared to $26,951 for DSRS patients.
Synthesis of costs and benefits The incremental cost effectiveness of TIPS compared with DSRS was $147,340 per life-year saved. The results of the sensitivity analysis did not alter the conclusions of the study.
Authors' conclusions In patients with Child's class A cirrhosis, DSRS is a more cost-effective treatment than TIPS. Until the results of a randomised controlled trial comparing TIPS with DSRS are available, TIPS should be regarded as experimental and prohibitively expensive in Child's class A cirrhosis.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparators is clear as both procedures (TIPS and DSRS) were used in the settings considered by the authors. You, as a database user, should consider if this applies to your own setting.
Validity of estimate of measure of benefit The benefit measure was derived from a large number of probabilities in the literature as well as authors' own estimates. There is evidence of a systematic approach in searching the literature but models of this nature have some well-accepted limitations in terms of data reliability and consistency. However, sensitivity analyses were performed which will have partially overcome these limitations.
Validity of estimate of costs The analysis was performed from the payer's perspective and no important elements were missed in this context. The authors addressed the issue of using charges by converting them to costs, and this will increase the generalisability of the cost results.
Other issues The authors acknowledged the following limitations. Because the values used in the model do not come from randomised studies, the results used in the model are subject to selection bias, i.e. sicker patients may have had TIPS rather than DSRS. The authors noted that the literature used in the review comes from centres experienced in both DSRS and TIPS and so the results of the analysis may not be applicable in centres with less experience in the management of portal hypertension. They also noted that the model was restricted to two years, and that costs data come from the authors' setting and costs results do not account for the wide variations within the USA and in other countries.
Implications of the study The model is best used to inform, but not to make the decision whether to offer patients TIPS or DSRS and should be used to help define the questions that can only be answered in a randomised,controlled trial.
Source of funding Supported by grants from the National Institutes of Health (DK 076344 and DK34987), the American Digestive Health Foundation and the Glaxo Wellcome Institute for Digestive Health.
Bibliographic details Zacks S L, Sandler R S, Biddle A K, Mauro M A, Brown R S. Decision-analysis of transjugular intrahepatic portosystemic shunt versus distal splenorenal shunt for portal hypertension. Hepatology 1999; 29(5): 1399-1405 Indexing Status Subject indexing assigned by NLM MeSH Decision Support Techniques; Equipment Failure; Health Care Costs; Humans; Hypertension, Portal /mortality /surgery; Portasystemic Shunt, Transjugular Intrahepatic /economics; Splenorenal Shunt, Surgical /economics; Stents /adverse effects; Survival Analysis AccessionNumber 21999000877 Date bibliographic record published 31/03/2000 Date abstract record published 31/03/2000 |
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