Potential impact of a delayed ADAMTS13 result in the treatment of thrombotic microangiopathy: an economic analysis

BACKGROUND

A pre-plasma exchange ADAMTS13 measurement differentiates thrombotic thrombocytopenic purpura (TTP) from other forms of thrombotic microangiopathy (TMA). Given that many hospitals do not perform the ADAMTS13 assay in-house and that the turnaround time (TAT) differs among reference laboratories, we performed an analysis investigating the potential impact of a delay in obtaining the results on the healthcare system.

METHODS

An economic model was developed to estimate the impact of a delay in obtaining the pretreatment ADAMTS13 results on patients admitted with TMA with cost (US dollars) as the primary outcome. Incremental cost-effectiveness ratio (ICER) as a composite outcome was calculated from both cost and life days [LDs], an effectiveness surrogate marker. Model parameters were gathered from the medical literature, except for the institutional cost of the ADAMTS13 test.

RESULTS

In patients with TMA, during the 6-day study period, the incremental cost to the healthcare system ranged from approximately $4155 to $5123 for every 1-day delay in obtaining the pre-exchange ADAMTS13 results with virtually no change in the effectiveness marker. The ICER composite outcome established the cost-effectiveness of having a fast TAT for pre-exchange ADAMTS13 results. Probabilistic sensitivity analyses also confirmed the robustness of the model.

CONCLUSIONS

In patients with clinical presentations of TMAs, having a rapid TAT for pre-exchange ADAMTS13 measurement appeared to be cost-effective. If testing cannot be performed in-house, then our findings support the necessity of contracting with a reference laboratory that can reliably provide the result, preferably within 1 day of admission.

An economic analysis of different treatments for bleeding in patients with acquired haemophilia

BACKGROUND

Acquired haemophilia A (AHA), with potentially high risk of morbidity and mortality, occurs as a result of inhibitors against factor VIII. Bleeding due to AHA can be treated with activated prothrombin complex concentrate (aPCC), recombinant activated factor VII (rFVIIa) or recently, recombinant porcine-sequence factor VIII (rpFVIII). We extended our previous cost-effectiveness analysis (CEA) comparing rpFVIII against the available traditional options.

METHODS

For high-titred, haemorrhaging AHA patients treated with either aPCC, rFVIIa or rpFVIII, over the course of 6-days, a Markov simulation was conducted to evaluate the outcomes when these patients transitioned into any of the four following health states: (1) continuous bleeding, (2) thrombosis, (3) stop bleeding and (4) death, with states (2), (3) and (4) modelled as absorbing states. All model parameters were obtained from the medical literature, except the costs of aPCC, rFVIIa and the factor VIII assay, which came from our institutional data.

RESULTS

Excluding the cost of the initial treatment on day 0, the total subsequent treatment cost of rFVIIa was substantially more than the costs of aPCC and rpFVIII ($13 925 vs. $1778 vs. $6957, respectively). The average quality-adjusted life days (QALDs) gained from rpFVIII was lowest (4·89 vs. 4·9 for rFVIIa and 4·91 for aPCC). Overall, aPCC dominated the other two treatments. The model was determined to be robust across the tested ranges for all input variables.

CONCLUSION

Based on this economic model, for AHA patients with high titres who were bleeding, aPCC was the most cost-effective treatment option and may be considered for use if there is no clinical contraindication.

Plasma Transfusion Demystified: A Review of the Key Factors Influencing the Response to Plasma Transfusion

Many studies have suggested that inappropriate plasma usage is common. An important factor contributing to futile plasma administration in most patients is the nonlinear relationship between coagulation-factor levels and the volume of plasma transfused. In this review, a validated mathematical model and data from the literature will be used to illuminate 3 key properties of plasma transfusion. Those properties are as follows: the effect of plasma transfusion on international normalized ratio (INR) is transient; for the same volume of transfused plasma, a greater reduction in INR is observed at higher initial INRs; and the effect of plasma transfusion on INR correction (ie, the difference between initial and final INRs) diminishes as more plasma is transfused. Frequent misunderstanding of these properties may contribute to inappropriate plasma usage. Therefore, this review will assist physicians in navigating these common pitfalls. Stronger understanding of these principles may result in a reduction of inappropriate plasma transfusions, thus potentially enhancing patient safety and reducing healthcare costs.

ADAMTS13 test and/or PLASMIC clinical score in management of acquired thrombotic thrombocytopenic purpura: a cost-effective analysis

BACKGROUND

The ADAMTS13 test distinguishes thrombotic thrombocytopenic purpura (TTP) from other thrombotic microangiopathies (TMAs). The PLASMIC score helps determine the pretest probability of ADAMTS13 deficiency. Due to inherent limitations of both tests, and potential adverse effects and cost of unnecessary treatments, we performed a cost-effectiveness analysis (CEA) investigating the benefits of incorporating an in-hospital ADAMTS13 test and/or PLASMIC score into our clinical practice.

STUDY DESIGN AND METHODS

A CEA model was created to compare four scenarios for patients with TMAs, utilizing either an in-house or a send-out ADAMTS13 assay with or without prior risk stratification using PLASMIC scoring. Model variables, including probabilities and costs, were gathered from the medical literature, except for the ADAMTS13 send-out and in-house tests, which were obtained from our institutional data.

RESULTS

If only the cost is considered, in-house ADAMTS13 test for patients with intermediate- to high-risk PLASMIC score is the least expensive option ($4,732/patient). If effectiveness is assessed as measured by the number of averted deaths, send-out ADAMTS13 test is the most effective. Considering the cost/effectiveness ratio, the in-house ADAMTS13 test in patients with intermediate- to high-risk PLASMIC score is the best option, followed by the in-house ADAMTS13 test without the PLASMIC score.

CONCLUSIONS

In patients with clinical presentations of TMAs, having an in-hospital ADAMTS13 test to promptly establish the diagnosis of TTP appears to be cost-effective. Utilizing the PLASMIC score further increases the cost-effectiveness of the in-house ADAMTS13 test. Our findings indicate the benefit of having a rapid and reliable in-house ADAMTS13 test, especially in the tertiary medical center.