David Chandiwana

University of Adelaide, Tarndarnya, South Australia, Australia

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Publications (5)6.09 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND AND OBJECTIVES: Regular blood transfusions for beta-thalassaemia patients lead to the accumulation of iron deposits in the body. In order to remove such deposits, iron chelation therapy is required. Subcutaneously administered deferoxamine has been the gold standard chelation therapy for over 40 years. Deferasirox is a newer chelation therapy that is taken orally once daily. The objective of this study was to estimate the long-term costs and quality-adjusted life-years (QALYs) associated with deferoxamine and deferasirox in a cohort of transfusion-dependent beta-thalassaemia patients from a UK health service perspective. METHODS: A 50-year annual cycle state transition model comprised three core health states: alive without cardiac complications, alive with cardiac complications, and dead, as well as representing other chronic complications of iron overload: diabetes, hypogonadism, hypoparathyroidism and hypothyroidism. The model was calibrated to identify sets of convergent input parameter values that predicted observed overall survival by mean lifetime compliance with chelation therapy. A pivotal non-inferiority trial informed the main estimates of the effectiveness of deferasirox, which were applied to the calibrated model. Using cost values for the year 2011, costs and utilities were summed over patients' lifetimes to estimate lifetime costs and QALY gains. RESULTS: Mean lifetime treatment costs for patients receiving deferoxamine were £70,000 higher than deferasirox. Drug acquisition costs were £100,000 higher for deferasirox, but administration costs associated with deferoxamine were £170,000 higher. Higher compliance associated with oral deferasirox administration led to fewer complications. Combined with the quality-of-life effects of an oral mode of administration, an average gain of 4.85 QALYs for deferasirox was estimated. In the base case, deferasirox dominates deferoxamine, i.e., costs less and patients gain more QALYs. The key parameter is the proportion of deferoxamine patients using balloon infusers. Sensitivity analyses showed that even when the proportion of patients using balloon infusers is decreased from 79 to 25 %, the incremental cost per QALY gained remains well under £20,000. CONCLUSION: Higher drug acquisition costs for deferasirox are offset by the avoidance of infusion-related equipment costs. Combined with health benefits derived from an oral mode of administration and improved compliance, deferasirox has a high probability of being a cost-effective intervention compared with deferoxamine.
    Clinical Drug Investigation 10/2012; · 1.70 Impact Factor
  • P Swinburn, J Wang, D Chandiwana, W Mansoor, A Lloyd
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    ABSTRACT: Neuroendocrine tumours (NETs) are a rare form of neoplasm that can arise in most organs of the body and which share many common pathologic features. Although curative surgery can be conducted for patients with localised disease, once progression occurs and the disease becomes metastatic or un-resectable, treatment aims to extend life and maintain quality-of-life for as long as possible. The aim of the study was to elicit utilities for health state vignettes describing the burdens associated with receiving therapy for advanced NETs. Health state vignettes were developed by reviewing published literature and conducting in-depth interviews with patients and clinical experts. These states described the burden associated with both stable and progressive disease, in addition to the experience of a number of serious toxicities commonly associated with treatments (grade III/IV diarrhoea, hand-foot syndrome, hyperglycaemia, nausea/vomiting, pneumonitis, rash, stomatitis, and thrombocytopenia). One hundred members of the UK general public valued the states using the time trade-off methodology to determine utility values. Stable disease had a utility value of 0.77 whilst disease progression was associated with a significant decline in health-related quality-of-life (HRQoL) and a value of 0.61. Toxicities experienced in the context of stable disease exhibited varying degrees of impact, with several being deemed as debilitating as disease progression (such as hand-foot syndrome [0.58] and stomatitis [0.56]). Although vignette studies have been criticised for the difficulty in establishing their validity, the collection of health utilities in rare populations is challenging. The findings from this study suggest that advanced NETs is associated with a considerable HRQoL burden, both as a direct result of the disease and the potential of experiencing a number of severe adverse events. These values could assist in future economic evaluation processes.
    Journal of Medical Economics 02/2012; 15(4):681-7.
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    ABSTRACT: In the Medical Research Council Myeloma IX Study (MMIX), zoledronic acid (ZOL) 4 mg 3-4/week reduced the incidence of skeletal-related events (SREs), increased progression free survival (PFS), and prolonged overall survival (OS), compared with clodronic acid (CLO) 1600 mg daily, in 1970 patients with newly-diagnosed multiple myeloma (MM). An economic model was used to project PFS, OS, the incidence of SREs and adverse events and expected lifetime healthcare costs for patients with newly-diagnosed MM who are alternatively assumed to receive ZOL or CLO. The incremental cost-effectiveness ratio [ICER] of ZOL vs CLO was calculated as the ratio of the difference in cost to the difference in quality-adjusted life years (QALYs). Model inputs were based on results of MMIX and published sources. Compared with CLO, treatment with ZOL increases QALYs by 0.30 at an additional cost of £1653, yielding an ICER of £5443 per QALY gained. If the threshold ICER is £20,000 per QALY, the estimated probability that ZOL is cost-effective is 90%. The main limitation of this study is the lack of data on the effects of zoledronic acid on survival beyond the end of follow-up in the MMIX trial. However, cost-effectiveness was favourable even under the highly conservative scenario in which the timeframe of the model was limited to 5 years. Compared with clodronic acid, zoledronic acid represents a cost-effective treatment alternative in patients with multiple myeloma.
    Journal of Medical Economics 02/2012; 15(3):454-64.
  • Value in Health 01/2011; 14(7). · 2.19 Impact Factor
  • Value in Health 01/2011; 14(7). · 2.19 Impact Factor