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Cost savings and effectiveness of outpatient treatment with low molecular weight heparin of deep vein thrombosis in a community hospital |
Lee M, Pao D, Hsu T, Sonderskov A |
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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 The study examined a home care programme using low molecular weight heparin (LMWH), namely tinzaparin, for the treatment of uncomplicated deep vein thrombosis (DVT). Patients receiving home care were sent home on tinzaparin with a supply of 50 tablets of warfarin (2 mg).
Economic study type Cost-effectiveness analysis.
Study population The study population comprised patients who presented to the emergency department with uncomplicated DVT. The exclusion criteria included co-morbid illness requiring hospitalisation, suspected pulmonary emboli (other thromboembolic episode), haemodynamically unstable (myocardial infarction, thrombotic stroke), active bleeding (gastrointestinal haemorrhage, intracranial haemorrhage) and active peptic ulcer. Further criteria were age less than 18 years, pregnancy, and suspicion of poor patient understanding or compliance.
Setting The setting was the home and a hospital. The economic study was carried out in Canada.
Dates to which data relate The effectiveness and resource use data were gathered from January to December 1996 in the hospital group and from April 1997 to March 1998 in the home group. The price year was 1999.
Source of effectiveness data The effectiveness evidence was derived from a single study.
Link between effectiveness and cost data The costing was carried out retrospectively on the same sample of patients as that used in the effectiveness analysis.
Study sample All eligible patients identified through a search of hospital records at the authors' institution over the relevant study periods were enrolled in the study. Patients could be included more than once, in either or both groups, provided that the attending physician diagnosed the presenting DVT as a new clinical event occurring during the study period. In total, 129 eligible patients were identified. Of the 65 cases in the hospital group, 39 cases consisting of 39 different patients satisfied the eligibility criteria. Of the 64 cases in the home group, there were 39 different eligible patients. One patient was included in both the pre-and post-groups.
All 39 cases in the hospital group were hospitalised and treated with intravenous heparin. Thirty-two of the 39 home group cases were treated with tinzaparin at home, while 7 were treated with either tinzaparin or intravenous heparin in hospital. The authors noted that the reasons for hospitalisation were undocumented. The mean age was 59.36 years (median 60; age range: 20 to 92) in the hospital group (39 patients) and 60.72 years (median 66; age range: 31 to 81) in the home group (32 patients). The numbers of female participants were 26 (hospital group) and 14 (home group), respectively. For the 7 home group cases who received treatment at the hospital, the mean age was 54.71 years (median 61; age range: 25 to 79) and 4 were female. Power calculations were not reported.
Study design This was a retrospective cohort study with a historical control that was carried out at a single centre, the Centenary Health Centre Site of the Rouge Valley Health System in Canada.
Patients in the hospital group were treated at the authors' institution according to standard procedures. They were admitted to the hospital and treated with dose-adjusted intravenous heparin, given continuously with concomitant warfarin therapy until a therapeutic international normalised ratio (INR) range (>2.5 to 3.5) was achieved. Patients in the home group, after being clinically diagnosed with suspect DVT in the emergency unit, received one dose of tinzaparin and were scheduled for a Doppler test to confirm the diagnosis. If the test was not immediately available, patients could be kept overnight in the emergency room or on an inpatient unit. Alternatively, the patients could elect to go home and return the next day for the Doppler test. With a positive diagnosis, the patient was sent home and visited daily by a nurse who assessed the patient and administered the tinzaparin. A phlebotomist also visited the patients to take a blood sample for INR measurement.
Patients in the home care group were followed until they attained a therapeutic INR value, while patients in hospital were followed until their INR was in the therapeutic range or until the treating physician discharged the patient if that occurred early. No patient was lost to the follow-up assessment. Blinding was not performed.
Analysis of effectiveness All patients included in the initial study sample were considered in the analysis of effectiveness. The primary clinical outcomes used were time to reach a therapeutic INR and events such as death, related re-hospitalisation, thromboembolic episodes, pulmonary embolism and bleeding. In terms of the baseline comparability of study groups, the authors stated that, apart from the gender distribution, the groups differed only in that there were a lower proportion of patients with co-morbid conditions in the home group, compared with hospitalised patients in both groups.
Effectiveness results There was no difference between groups in the time to reach a therapeutic INR.
There were no deaths or major bleeding episodes during the study period.
Clinical conclusions The effectiveness analysis showed that the two treatments were equally effective and safe.
Measure of benefits used in the economic analysis No summary benefit measure was used in the economic analysis since the two treatments were equally effective and safe.
Direct costs The analysis of the costs was carried out from the perspective of the provincial government. It included both hospital and home costs. Hospital costs included all nursing care, meals, laboratory tests, medications, and so on. Home costs included hospital bed usage for patients who occupied a bed at the time of the bed census, home nurse visits, phlebotomist visits and drugs. The unit costs were presented separately from the quantities of resources used. Resource use was based on data derived from the sample of patients included in the effectiveness study. The costs were derived from a hospital financial report to the Ontario Ministry of Health (hospital costs), the Ontario Drug Benefit Formulary (drugs) and the hospital's regional Home Care Contractor (other items). Discounting was not relevant, owing to the short timeframe of the analysis, and was not carried out. The price year was 1999.
Statistical analysis of costs The Wilcoxon rank sum test was used to test for statistically significant differences in costs between the groups.
Indirect Costs The indirect costs were not included.
Sensitivity analysis A sensitivity analysis was carried out to assess the robustness of differences in the costs when using low and high cost estimates based on standard deviations around mean values.
Estimated benefits used in the economic analysis See the 'Effectiveness Results' section.
Cost results The mean costs per patient were CAD 3,266 in the hospital group and CAD 1,044 in the home group (CAD 584 among patients treated at home and CAD 2,923 among patients treated in the hospital).
The median costs per patient were CAD 3,300 in the hospital group and CAD 459 in the home group (CAD 429 among patients treated at home and CAD 2,640 among patients treated in the hospital).
Differences in costs between the groups reached statistical significance, (p<0.00001). There was no statistical difference in the cost per patient for hospitalised patients in the hospital and home groups.
Patients in the hospitalised group were characterised by a higher number of laboratory tests compared with patients in the home group.
The sensitivity analysis showed that home treatment was always associated with cost-savings in comparison with hospital treatment, except when low cost estimates for the hospital group and high cost estimates for the home group were used.
Synthesis of costs and benefits A synthesis of the costs and benefits was not relevant as, in effect, a cost-minimisation analysis was performed.
Authors' conclusions Home treatment with a low molecular weight heparin (LMWH) such as tinzaparin led to substantial cost-savings for the Canadian health care system, with no apparent change in effectiveness or safety in comparison with traditional hospital treatment.
CRD COMMENTARY - Selection of comparators The rationale for the selection of the comparators was clear in that the two treatments for patients with uncomplicated DVT were those used at the authors' institution. In addition, they would appear to be usual treatments in the Canadian setting. You should decide whether they are valid comparators in your own setting.
Validity of estimate of measure of effectiveness The effectiveness evidence came from a retrospective study, which is usually associated with some limitations. In particular, the potential impact of selection bias and confounding factors cannot be ruled out. However, since the two treatments were not used concurrently at the authors' institution, the choice of the design might have been appropriate given the objective of the study. The authors highlighted several potential limitations of their analysis. No justification for the size of the sample was provided and, owing to the small number of patients included in the analysis, it was unclear whether the results obtained were due to the intervention or to chance. The short time horizon of the study precludes an assessment of the true impact of the treatments on the patients' outcomes, since most relevant events could occur after hospital discharge. Given that the two groups were not studied concurrently, factors other than the study treatments could have affected the clinical end points. However, the authors pointed out that no major changes at their institution were observed. The two groups of patients were not perfectly matched at baseline and this could also have impacted upon the results of the analysis. The demographics of the patients were reported, but the evidence came from a single institution, which could limit the representativeness of the study sample. The retrospective nature of the study represents a limitation to its internal validity.
Validity of estimate of measure of benefit No summary benefit measure was used in the analysis. Please refer to the comments reported in the 'Validity of estimate of measure of effectiveness' field (above).
Validity of estimate of costs The perspective adopted in the study was appropriate. All the relevant categories of costs were included in the analysis. A breakdown of the cost items was provided, along with the unit costs. The sources of the items were reported; these represented typical sources for Canadian costs. Quantities of resources used were also provided, which enhances the possibility of replicating the analysis in other settings. The authors carried out some statistical analyses of the costs and the cost estimates were varied in the sensitivity analysis. The price year was stated, which will assist reflation exercises in other time periods.
Other issues The authors stated that some of their findings, such as complication rates, were comparable with those reported in other studies. However, the issue of the generalisability of the study results to other settings was not explicitly addressed, and only a few sensitivity analyses were carried out, which limits the external validity of the study. The study referred to patients with uncomplicated DVT and eligible for home treatment, and this was reflected in the authors' conclusions. The study did not investigate the impact of the treatments on quality of life, which could have been interesting given the nature of the interventions.
Implications of the study The study results supported the use of home treatment with LMWH for patients with uncomplicated DVT.
Source of funding Supported in part by Leo Pharma Inc.
Bibliographic details Lee M, Pao D, Hsu T, Sonderskov A. Cost savings and effectiveness of outpatient treatment with low molecular weight heparin of deep vein thrombosis in a community hospital. Canadian Journal of Clinical Pharmacology 2004; 11(1): e17-e27 Other publications of related interest Levine M, Gent M, Hirsh J, et al. A comparison of low molecular weigh heparin administered primarily at home with unfractionated heparin administered in the hospital for proximal deep vein thrombosis. N Engl J Med 1996;334:677-81.
Tillman DJ, Charland SL, Witt DM. Effectiveness and economic impact associated with a program for outpatient management of acute deep vein thrombosis in a group model health maintenance organization. Arch Int Med 2000;160:2926-32.
Koopman MM, Prandoni P, Piovell F, et al. Treatment of venous thrombosis with intravenous unfractionated heparin administered in the hospital as compared with subcutaneous low molecular weight heparin administered at home. N Engl J Med 1996;334:682-7.
Indexing Status Subject indexing assigned by NLM MeSH Adult; Aged; Aged, 80 and over; Ambulatory Care /economics /statistics & Cost Savings /economics /statistics & Cost-Benefit Analysis /economics /statistics & Female; Follow-Up Studies; Heparin, Low-Molecular-Weight /economics /therapeutic use; Hospitals, Community /economics /statistics & Humans; Male; Middle Aged; Venous Thrombosis /drug therapy /economics; numerical data; numerical data; numerical data; numerical data AccessionNumber 22006006187 Date bibliographic record published 30/11/2006 Date abstract record published 30/11/2006 |
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