The epidemiology of hypercapnic respiratory failure
Hypercapnic respiratory failure is a condition that is encountered commonly by many clinicians. It can occur in association with a range of respiratory, cardiovascular, metabolic and neurological disorders, either alone or in combination. Most of the current literature is limited to case series with specific underlying diagnoses or in receipt of a particular medical intervention. There have been no epidemiological studies on hypercapnic respiratory failure irrespective of the underlying cause. This thesis includes four original research publications addressing the epidemiology of hypercapnic respiratory failure. These studies are based on the same population, residents of the metropolitan area of Liverpool in Sydney, Australia. The first is a cross-sectional study describing, for the first time, the prevalence of this condition within a given population. The second study uses medical record data to describe the frequency of potential causes. The third is a field study in which cases of hypercapnic respiratory failure are compared with control participants recruited from the same population. This case-control study is the first to describe causal associations with reference to a control group. The fourth is an historical cohort study using linked health data to describe clinical outcomes including rates of death and rehospitalisation. There are several important findings arising from this work. Hypercapnic respiratory failure is shown to be a common condition, affecting 163 (95% confidence interval 154 to 172) cases per 100,000 population. The most important risk factor in a population is confirmed to be chronic obstructive pulmonary disease, with opioid use and congestive heart failure also demonstrated to be substantial contributors. The standardised mortality ratio of 9.2 (95% confidence interval 7.6 to 11.0) indicates a near ten-fold risk of death compared with unaffected persons of a similar age. The body of work comprising this thesis represents a significant contribution to knowledge regarding the epidemiology of hypercapnic respiratory failure. This information is of fundamental importance in both clinical practice and health policy. The data provided in these studies allows for comparison across multiple populations and forms a foundation for future studies including evaluation of interventions directed at prevention and management.
hypercapnia, hypoventilation, anzsrc-for: 4202 Epidemiology, anzsrc-for: 3201 Cardiovascular medicine and haematology, anzsrc-for: 32 BIOMEDICAL AND CLINICAL SCIENCES
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