Medicine (St Vincent's) - Theses

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    Assessment of inflammatory bowel disease epidemiology in Barwon, Victoria: an observational prospective population based study
    Studd, Corrie Robert ( 2013)
    Background: The Inflammatory bowel diseases (IBD) Crohn’s disease (CD), ulcerative colitis (UC), and IBD unspecified (IBDU), are chronic conditions with significant health-related disability and potentially expensive therapies. Recent research locally suggests high IBD incidence rates. However, no Australian population-based prevalence data is available, nor has the natural history of newly diagnosed community-based IBD patients been studied. Aims: To estimate current IBD burden by calculating incidence and prevalence rates in an Australian population, and to assess for recent changes in IBD incidence. We also aimed to form a pilot IBD registry, allowing longitudinal observations of natural history in newly diagnosed community-based patients. Methods: The study region of Barwon, Victoria (population 293,426) was studied from July 1st 2010 to June 30th 2011. Capture-recapture methodology was used, with cases identified from multiple overlapping sources including clinicians (gastroenterologists, surgeons and paediatricians), histopathology databases, endoscopy records, hospital coding and medication dispensing records. Strict internationally recognised diagnostic criteria were used to define incident cases. All incident cases were individually verified by 2 clinicians and phenotypes defined by Montreal criteria. Incident cases were enrolled in a registry with opt-out consent. Prevalent case ascertainment required extension of data collection into General Practices across the region. Three-month clinical outcomes were assessed for incident cases, including surgical rates, hospitalisation and medication use. Results: 71 incident IBD cases were identified (incident rate 24.2 per 100,000). This was stable compared to local data from 2007/08. Incidence rates for CD, UC and IBDU were 14.7, 7.5 and 2.0 per 100,000 respectively. 1011 prevalent IBD cases were recorded (point prevalence rate on June 30th 2011 344.6 per 100,000). Prevalence rates for CD, UC and IBDU were 197.3, 136.0 and 8.5 per 100,000 respectively. All incident cases were enrolled in the registry. Within three months of diagnosis 28% had been hospitalised, and 11% required surgery (all with CD). Peri-anal disease was present in 14% of CD cases. 55% were under 40 years of age. Corticosteroids were prescribed in 59% and immunosuppression in 11%. None received biological therapy within three months of diagnosis. Conclusion: This study has produced Australia's first epidemiologically sound population-based IBD prevalence data, demonstrating a large burden of disease. Stable high IBD incidence rates were reconfirmed. Three month outcome data from the incident inception cohort shows a high proportion have aggressive disease, defined by age less than 40 at onset, hospitalisation and surgery rates, steroid use, and the presence of peri-anal disease. This inception cohort will be followed longitudinally to further define the natural history of IBD.
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    Epidemiology, natural history and impact of inflammatory bowel disease in Australia
    Wilson, Jarrad Leigh ( 2010)
    The inflammatory bowel diseases (IBD), Crohn’s disease (CD) and ulcerative colitis (UC), are chronic inflammatory disorders of the gastrointestinal tract. International studies have demonstrated a dramatic rise in the incidence of these conditions over the past several decades. There are no corresponding studies from Australia to determine the local incidence. CD has been shown to have a complicated disease course, with high requirements for surgery and progression to disability. Psychological morbidity is also common, with a negative impact on health related quality of life. International studies have also demonstrated high direct and indirect health economic costs associated with CD. Australian data in each of these areas is either limited or totally absent. The aim of this work was to address the deficiencies in each of these key areas. The first Australian population-based study of IBD incidence was conducted prospectively over a one-year period in the region of Barwon. This utilised an extensive capture-recapture methodology, with near complete case identification and rigorous verification of diagnosed cases. The IBD incidence rates observed are among the highest reported in the world literature. The natural history of CD was then assessed in a retrospective, inception cohort study over a five-year period from the time of diagnosis. There was the progressive development of a more complicated disease phenotype, with high requirements for surgery. The results from surgery were not durable, with 60 percent needing escalation of therapy within 5 years. 41 percent of the cohort met the definition of disabling disease, with the presence of perianal fistulae at diagnosis highlighted as a key risk factor. This was followed by two cross-sectional, questionnaire-based, cohort studies to assess psychological health and health related quality of life (HRQoL) in CD. The first study was conducted in patients from the Inflammatory Bowel Disease Clinic at St. Vincent’s Hospital, Melbourne. The second was in a cohort of patients from the same institution who had required the formation of an ileostomy for CD. Both studies revealed high rates of depression, anxiety and poor HRQoL. These negative factors were contributed to by increased disease activity, but the strongest predictive factor was found to be the use of a negative, maladaptive coping style. Some patients with a stoma have adapted well, but others found it to be a negative experience, with ongoing concerns regarding sexuality and body image. The health economic costs of CD were then established using prospective cost diaries. Both direct and indirect costs were high, in keeping with the complicated natural history of CD. These studies highlight that IBD is common in Australia, and that CD has a complicated natural history, with negative impacts on psychological health and HRQoL, and with high economic costs. There is a need for increased public awareness as well as ongoing research and funding to improve clinical care.