Results of a model analysis to estimate cost utility and value of information for intravenous immunoglobulin in Canadian adults with chronic immune thrombocytopenic purpura.

OBJECTIVE: The aim of this work was to estimate the cost-effectiveness of intravenous immunoglobulin (IVIg) compared with oral prednisone as a treatment for Canadian adults with persistent chronic immune thrombocytopenic purpura (ITP). METHODS: The lifetime costs and effectiveness of IVIg and prednisone were estimated from the perspective of a publicly funded health care system in Canada, using a Markov model that was developed based on a systematic clinical and economic review and recommendations of clinical experts in Canada. Transition probabilities (ie, point estimates and 95% CIs) were estimated from the studies identified in a systematic literature review using a random-effect meta-analysis; point estimates were weighted-mean values from the meta-analysis. No published studies directly estimate the utility weight for patients with relapsed or refractory ITP; therefore, a value of 0.76 was used, based on the mean of the utilities for thrombocytopenia without major bleeding or hemorrhagic stroke. Costs and incremental cost-effectiveness ratios were reported as year-2007 Can $. RESULTS: The incremental costs and quality-adjusted life-years (QALYs) of IVIg versus prednisone were Can $8080 and 0.0071, respectively, resulting in an incremental cost-effectiveness ratio of Can $1.13 million/ QALY in the base-case analysis. The probability of IVIg being cost-effective was 0 if the maximum willingness-to-pay (WTP) value for an additional QALY was below Can $40,000. The probability that IVIg would be cost-effective was only 20%, even if the WTP increased to Can $100,000. The expected value of perfect information (EVPI) and expected value of partial perfect information (EVPPI) were 0 if the WTP was less than Can $30,000. If WTP increased to Can $100,000, the EVPI was Can $1700, and the EVPPI was Can $1010 for utility weights of relapse/refractory states, Can $136 for initial response rates of the treatments, and Can $6 for first-year relapse rates for the treatments. CONCLUSION: Based on the current available clinical evidence, this model analysis of hypothetical patients suggests that IVIg may not be a cost-effective option for adults with persistent chronic ITP in Canada.

Survey of the use and clinical effectiveness of HPA-1a/5b-negative platelet concentrates in proven or suspected platelet alloimmunization.

The optimal treatment of neonatal alloimmune thrombocytopenia (NAIT) is the transfusion of compatible donor platelets. The National Blood Service in England has established panels of "accredited" donors negative for human platelet antigens HPA-1a and HPA-5b, the most commonly implicated alloantigens. We have retrospectively surveyed the frequency of use and clinical effectiveness of donations collected over a 13-month period from the Oxford accredited panel. Ninety-five per cent of hyperconcentrated platelets (HPCs) collected were issued, all for intrauterine transfusion to fetuses at risk of NAIT due to the presence of maternal platelet alloantibodies and previously affected siblings. Thirty-one per cent of paediatric platelet concentrates (PPCs) collected were issued, of which 57% were used for cases of suspected NAIT. Fifty-four per cent of adult therapeutic doses collected were issued; 5% of these were used in cases of suspected NAIT or proven post-transfusion purpura (PTP). Good increments were seen in most NAIT cases transfused with HPCs or PPCs, and a moderate increment in the one PTP case. We conclude that the establishment of accredited panels is justified and enables delivery of a clinically effective treatment for NAIT. Increased use and cost-effectiveness could be achieved by the delivery of an educational programme to neonatal unit clinical staff to increase the awareness and appropriate treatment of NAIT.

The cost of treating immune thrombocytopenic purpura using intravenous Rh immune globulin versus intravenous immune globulin.

Multiple factors, including efficacy, toxicity and cost, may influence the decision to treat immune thrombocytopenic purpura (ITP) with intravenous immune globulin (IVIG) or intravenous Rho (D) immune globulin (IV RhIG). We conducted a survey of 50 hospitals in 31 states to determine the costs for treating ITP using conventional doses for IVIG or IV RhIG, based on package insert recommendations. The average cost for a dose of IVIG ($2,771) was 71.7% ($1,157) more than that for a dose of IV RhIG ($1,614). In the absence of clearly defined differences in clinical outcomes when treating ITP with IVIG or IV RhIG, the difference in cost may be an important factor in selecting the treatment.

Cost-effectiveness of splenectomy versus intravenous gamma globulin in treatment of chronic immune thrombocytopenic purpura in childhood.

Infusions of intravenous gamma-globulin (IVGG) are an effective, nontoxic therapy for chronic idiopathic thrombocytopenic purpura (ITP) that would be more widely accepted if the therapeutic agent were not so expensive. The costs and outcomes of managing such children with splenectomy and IVGG were modeled with Markov processes. Children unresponsive to one treatment were considered to have received the alternative. The model accounted for spontaneous remissions, therapeutic responses, traumatic events, episodes of sepsis, and operative deaths. For a 10-year-old child with chronic ITP, the strategy of initial treatment with splenectomy had associated costs of $17,000 and a 97.9% ten-year survival rate, whereas the strategy of initial treatment with IVGG had associated costs of $21,000 but a 98.6% survival rate. Each additional life saved by employing the IVGG strategy cost $540,000, or $8,000 per year for a life expectancy of 70 years. Sensitivity analyses demonstrated that for older children the IVGG strategy continued to result in improved survival rates but was more costly than the splenectomy strategy. For younger children, the IVGG strategy dominated, with improved survival rates and lower costs.