Academic journal article Australian Health Review

Costs Associated with Hereditary Haemochromatosis in Australia: A Cost-of-Illness Study

Academic journal article Australian Health Review

Costs Associated with Hereditary Haemochromatosis in Australia: A Cost-of-Illness Study

Article excerpt

Introduction

Hereditary haemochromatosis is a common autosomal recessive disorder among people of northern European ancestry.1-3 Clinically, haemochromatosis is characterised by increased absorption of dietary iron, which is stored in the parenchymal tissues of the liver, heart and pancreas. If untreated, this can be the cause of morbidity, including Type 2 diabetes (T2D), heart disease and liver disease.

Although several mutations of the high iron Fe (HFE) haemochromatosis gene have been identified, individuals homozygous for the C282Y mutation account for between 80% and 90% of morbidity and mortality.4,5 Other mutations are rarely observed to cause comorbidity related to iron overload.6,7 Between 1:150 and 1: 200 people of northern European ancestry are estimated tobeC282Y homozygotes; in other populations, the prevalence of this mutation is considerably lower to nonexistent.7-12

As iron stores increase, symptoms may progress from lethargy and arthropathy of the metacarpophalangeal joints to T2D, liver disease and heart disease. Symptoms of iron overload are most commonly reported in male patients aged >30 years; symptom onset is typically later in females as menstruation reduces iron stores.7,13,14

Clinical penetrance (individuals exhibiting symptoms) is incomplete and widely differing rates have been reported. For C282Y homozygotes, reported rates vary between 2% and 76%.4,5,7,8,15-26 This variance can be explained, in part, by the use of different definitions of penetrance: iron studies with different iron elevation cut-off points, clinically assessed symptoms or self-reported symptoms.27 For other common genotypes, such as the H63D and S56C mutations, clinical penetrance is much lower, with some authors noting no association between the S56C allele and elevated transferrin saturation.28

This issue of differing definitions of clinical penetrance and the resulting lack of generalisability of much of this body of research was recognised by the European Association for the Study of the Liver (EASL). In 2000, a consensus document was published outlining four categories of disease (Table 1).27 These categories have been adopted by a small number of other studies. One study reported penetrance of C282Y homozygosity, defined as Categories 2 through to 4, as 15.8%; 12.1% for Categories 3 and 4 and 2.9% for Category 4.29 Similarly, an Australian study of a random sample of participants reported a penetrance rate, defined as Categories 3 and 4, of 13.9% among C282Y homozygotes.8

The diagnosis and treatment of haemochromatosis are relatively straightforward. Diagnosis involves conducting serum iron studies (transferrin saturation and serum ferritin) followed by confirmatory HFE genotyping. Treatment consists of regular therapeutic venesection.30 When treatment is commenced before irreversible organ damage, the patient retains normal life expectancy.2,30 Because early symptoms of iron overload are non-specific, in some cases diagnosis occurs subsequent to organ damage.31,32 Population screening programs have been suggested to increase the rate of early diagnosis, thereby reducing morbidity and mortality associated with haemochromatosis.27,33-35 To date, no quantification of the costs of haemochromatosis has been published. A cost-of-illness (COI) study estimates all relevant costs from the perspectives of the patient, government and/or society. The preferred method is a bottom-up COI analysis that incorporates observational data.36 The aim of the present study was to calculate the health sector, other sector and time-loss costs of haemochromatosis from the societal, government and patient perspectives for the Australian setting.

Methods

A web-based cross-sectional COI study using convenience sampling was conducted across Australia between November 2013 and February 2015. Multiple recruitment strategies were used to maximise participation: emails were sent to all members of the national haemochromatosis support group (Haemochromatosis Australia (HA)) informing them of the project and the web address, a link to the survey was placed on HA's website and flyers were sent to large Australian metropolitan hepatology, haematology and gastroenterology clinics, along with general practitioners (GPs) sourced from HA' s referral network. …

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