Health and economic consequences of HCV lookback Pereira A

Transcription

1 Health and economic consequences of HCV lookback Pereira A 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 use of a programme of lookback on blood recipients, aimed at identifying those who may have acquired posttransfusion hepatitis C virus (HCV) before the implementation of anti-hcv screening. Type of intervention Screening. Economic study type Cost-utility analysis. Study population The study population comprised general recipients of blood. The specific inclusion and exclusion criteria were not reported. Setting The setting was an institution. The economic study was carried out at the Hospital Clinic in Barcelona, Spain. Dates to which data relate The effectiveness and resource use data were derived from studies published between 1993 and The price year was not reported. Source of effectiveness data The effectiveness evidence was derived from several published studies. Modelling A Monte Carlo simulation of a Markov model, adapted from one published elsewhere (see Other Publications of Related Interest), was conducted to simulate the natural history of post-transfusion HCV of 10 million patients in two cohorts of blood recipients undergoing or not undergoing HCV lookback. It was assumed that lookback was performed 10 years after transfusion. The post-lookback course of each newly diagnosed HCV-positive patient (lookback arm) was compared with what would have been his or her health status if the lookback had not been performed (control arm). Apart from baseline health (health status of patients who cleared the infection after antiviral therapy), four possible health states were accounted for in the progression of HCV: asymptomatic chronic carriers, i.e. patients who had no symptoms and whose alanine aminotransferase levels were normal; <MODELLING>> the status of chronic hepatitis, i.e. mild symptoms, alanine aminotransferase levels persistently high, and moderate to severe fibrosis or frank cirrhosis found in the liver biopsy; Page: 1 / 6

2 clinical liver failure, i.e. clinical complications of decompensated cirrhosis or hepatocellular cancer requiring hospitalisation; and the status of liver transplant for eligible patients. Each individual entered the model separately, acting as his (or her) own control, and left after death. The cycle length was 3 months. Several published studies were used to derive the data used to populate the model. However, the probability distributions for the age and the gender of the blood recipients were derived from a population of 9,961 patients who received transfusion at the Hospital Clinic (Barcelona) from July 1996 to December Outcomes assessed in the review The outcomes assessed from the literature were the transition probabilities for: the transition to clinical liver failure in the first 6 years after transfusion and in subsequent years; the mortality after clinical liver failure in men and women (factor that multiplies the age- and gender-adjusted mortality rate); and the mortality rate after liver transplant during the first year, during the second and third years, and during the fourth and fifth years. Quality of life factors assigned to the model health states were also assessed. Study designs and other criteria for inclusion in the review Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included The effectiveness evidence was derived from five studies. Methods of combining primary studies Investigation of differences between primary studies Results of the review The transition to clinical liver failure was 0 in the first 6 years after transfusion, and in subsequent years. Page: 2 / 6

3 The mortality rate after clinical liver failure was 3.1 in men and 2.8 in women. The mortality rate after liver transplant was during the first year, during the second and third years, and during the fourth and fifth years. The quality of life values were: 1 for both baseline health and an asymptomatic chronic carrier; 0.90 for chronic hepatitis; 0.50 for clinical liver failure; and for liver transplant, 0.50 during the first quarter, 0.75 during the second and fourth quarters, and 0.85 during the second and subsequent years. Measure of benefits used in the economic analysis The main benefit measure used in the economic analysis was the number of quality-adjusted life-years (QALYs). The estimation of QALYs was obtained from the decision model. A 3% discount rate was used for future benefits associated with the screening strategy. The unadjusted and nondiscounted survival years and rate of complications in both patient groups were also calculated. The quality of life measure was reported in the paper in which the model was described (see Other Publications of Related Interest). Direct costs Since the time horizon of the study was 10 years, the future costs associated with lookback were discounted at a rate of 3%. The quantities and the unit costs were not reported separately, although the cost details were stated to have been reported elsewhere (see Other Publications of Related Interest). The resource/cost boundary adopted was consistent with the perspective adopted in the analysis, i.e. that of the National Health Service. The cost analysis consisted of the direct costs. In the lookback arm, the direct costs were for the antiviral treatment (interferon), for the medical follow-up of patients not eligible or not responding to interferon, and for the treatment of liver failure in patients who progressed to this health stage. The costs in the control arm included only those for treating liver failure. It was assumed that the possible costs incurred before the lookback were similar in both study arms. The single item costs were derived from studies published in The total cost of each strategy was calculated from the decision model. The price year was not reported. Statistical analysis of costs No statistical analysis of costs was reported. Indirect Costs The indirect costs were not included. Currency US dollars ($). Sensitivity analysis One-way sensitivity analyses were conducted to assess the robustness of the model to input variations, and the impact of some factors on the analysis results. The parameters varied were the patient's age at the time of transfusion, the discount rate, and possible improvements in the efficacy of anti-hcv therapies. Page: 3 / 6

4 Estimated benefits used in the economic analysis All benefits were per newly diagnosed HCV-positive patient. Forty-seven per cent of those receiving HCV-infective blood 10 years previously were predicted to be HCV positive, alive and not to have progressed to liver failure. The remaining theoretical life expectancy was, of course, the same in both patient groups and was equal to years. The unadjusted survival was greater in the lookback group ( years) than in the control group ( years) by years (45 days). The QALYs were in the lookback group and in the control group. The gain associated with the lookback screening was QALYs (28 days). Cost results The costs were $1,618 for the follow-up of asymptomatic carriers, $392 for the follow-up of chronic hepatitis, and $100 for interferon therapy (relevant only in the lookback group). The costs for the conventional treatment of liver failure and liver transplant were $9,859 and $2,864 in the lookback group. The corresponding values in the control group were $10,605 and $3,307. The total expected costs per newly diagnosed HCV positive patient were $14,833 in the lookback group and $13,912 in the control group. There was a net present value of the lifetime costs associated with every new HCV-positive patient of $921. Synthesis of costs and benefits The costs and the benefits were not combined. The sensitivity analyses indicated that the patient's age at the time of transfusion had a great impact on both the costs and the survival. With respect to the latter, patients who were neonates when transfused could gain, on average, years of life expectancy. However, those who were older than 60 years at the time of lookback would obtain no benefit. The results of the study were also sensitive to changes in the discount rate, hypothetical negative impact factors, and improvements in the efficacy of antiviral therapy. Finally, when the time elapsed from transfusion to lookback was varied from 8 to 26 years (10 years in the base-case), the percentage of patients in the initial cohort who would remain alive and without liver failure decreased. The benefit gain increased up to 20 years and then decreased. The cost gain decreased up to 20 years and then increased. Authors' conclusions The authors concluded that, in the cohort of patients studied, the lookback intervention performed 10 years posttransfusion could increase the average patient's survival by about 45 days. The benefits gained, which represented only 7% of the life span that the patient would lose because of post-transfusion HCV, were quite small. This was mainly due the low efficacy of anti-hcv therapies, and the advanced age and concomitant diseases of many blood recipients, who were not eligible for interferon therapy. There was a reduction in the medical costs due to the smaller number of patients requiring expensive treatments. However, this was more than offset by the costs of "the medical interventions triggered by the lookback in newly diagnosed patients, mainly the costs of follow-up of asymptomatic patients with mild hepatitis, most of whom will never progress to the point of requiring additional medical interventions". Great net savings could be realised if the interventions were focused on only young individuals, who were eligible for interferon therapy, in whom the disease could progress. CRD COMMENTARY - Selection of comparators The reason for the selection of the comparator was clear. In order to assess the potential value of lookback, the strategy was compared to one of no lookback. You should consider whether these technologies are appropriate to your own setting. Validity of estimate of measure of effectiveness The effectiveness evidence was derived from a review of the published literature. One of the main sources was a study Page: 4 / 6

5 of the model, conducted by the same author as the present analysis. The conduct and method of the review were not reported in detail. For example, there were no details given of the sources searched to identify the studies. In addition, the methods used to select the studies, assess their quality, and extract the data, were not provided. The contribution of each study to the effectiveness estimations was not reported. Validity of estimate of measure of benefit The benefit measure (QALYs) was modelled using a Markov model to represent the natural history of the disease. This appears to have been appropriate for the disease considered. Unfortunately, the source of the quality weights appears to have been described in the other paper by the same author (see Other Publications of Related Interest). A sensitivity analysis was performed but unfortunately it did not assess cost-effectiveness. In other words, the benefits and the outcomes were not combined to form a single statistic with which to estimate whether there would be a net benefit. Validity of estimate of costs The costs were mainly estimated from the literature. However, extensive sensitivity analyses were conducted to assess the uncertainty around the data used in the model. Again, unfortunately, the sensitivity analysis did not assess the combined effect on the costs and the benefits. The costs and the quantities were not reported separately. The price year was not indicated. The costs of the lookback campaigns included the tracing, contacting and testing of the blood recipients. However, these costs were not included in the study because, as the authors stated, the aim of the study was not to assess the impact of the whole HCV lookback effort. Instead, the aim was to estimate the health and economic repercussions after a lookback intervention was conducted. The authors stated that, when approximate campaign costs were included in the analysis, the estimated cost-effectiveness ratio of a targeted lookback should exceed $300,000 per QALY gained. Other issues The authors made few comparisons of their results with those from other studies. The issue of generalisability of the analysis findings was not explicitly addressed. However, several sensitivity analyses were conducted on crucial variables used in the model, although not in terms of the possible net benefit. The authors acknowledged that the assumptions used in the model could have overestimated the health impact of post-transfusion HCV. A further issue related to the possibility that HCV lookback could result in an unintended loss of health, due to psychological factors which could reduce the patients' sense of well-being when conscious of the presence of a chronic and potentially deadly disease. Implications of the study The authors highlighted that more effective and targeted antiviral therapies are required, which can also be used for older patients. Further, lookback interventions should be limited to those transfusion recipients under the age limit for antiviral therapy. Finally, "care should be taken to avoid the possibility that pursuing a major health gain for a minority might result in an unintended health loss for the majority". Unfortunately, although the study provided estimates of the benefit of lookback in HCV-infected blood-transfused patients, it did not fully account for the costs. The authors provide a single, non-validated estimate of the cost of lookback in the discussion, in order to estimate costeffectiveness. Incorporating this component in the main study would have enabled an assessment of the costeffectiveness of lookback and its sensitivity to variation in input parameters. Source of funding None stated. Bibliographic details Pereira A. Health and economic consequences of HCV lookback. Transfusion 2001; 41(6): PubMedID Page: 5 / 6

6 Powered by TCPDF ( Other publications of related interest Pereira A, Sanz C. A model of the health and economic impact of posttransfusion hepatitis C: application to costeffectiveness analysis of further expansion of HCV screening protocols. Transfusion 2000;40: Indexing Status Subject indexing assigned by NLM MeSH Blood Transfusion /adverse effects /economics; Costs and Cost Analysis; Hepacivirus; Hepatitis C /economics /transmission; Humans; Markov Chains; Monte Carlo Method AccessionNumber Date bibliographic record published 31/07/2002 Date abstract record published 31/07/2002 Page: 6 / 6