Risk factors for hospital readmission in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is associated with deterioration in lung function, poor health status and high mortality, morbidity and healthcare costs. Globally, COPD is the third leading cause of death, accounting for 4.7 million annual deaths worldwide. In Australia, 14.5% of people aged 40 years and over have COPD, and it is the 5th leading cause of death. Furthermore, COPD is one of the most common chronic conditions associated with potentially preventable hospitalisation in Australia. Acute exacerbation is one of the main reasons for hospital admission and readmission of patients with COPD, with severe negative impacts both for the patient and the healthcare system. Prevention of exacerbation of COPD has been recognised as an international priority to combat patients' deterioration and reduce associated healthcare costs. Twenty percent of patients admitted to hospital with an exacerbation of COPD will be readmitted within 30 days, and 50% will be readmitted within six months of hospital discharge. Several studies in Australia have addressed associated factors and trends in all-cause readmission for COPD, but none have explored readmission specifically for COPD. The work described in this thesis was aimed at identifying the prevalence of and risk factors for COPD-related hospital readmission. The specific objectives were to: (i) summarise and evaluate the published evidence on the prevalence of readmission for COPD and the risk factors and outcomes associated with readmission due to COPD, and (ii) investigate the prevalence of and risk factors for COPD readmission in Tasmania. The last systematic review on risk factors for hospitalisation and all-cause readmission of COPD patients was published in 2007. There were no systematic reviews on risks factors for COPD related readmission. Therefore, a systematic review of the literature was conducted to summarise the prevalence, risk factors and associated outcomes for COPD-related readmission. Fifty-seven studies from 30 countries were included in the review. The prevalence of COPD-related readmission varied from 2.6-82.2% at 30 days, 11.8-44.8% at 31‚Äö-90 days, 17.9-63.0% at 6 months, and 25.0-87.0% at 12 months post-discharge. The heterogeneity between studies precluded a meta analysis. Hospitalisation in the previous year was the principal risk factor for COPD-related readmission. Variation in the prevalence and the reported factors associated with COPD-related readmission indicated that risk factors cannot be readily generalised, and interventions should be tailored to the local healthcare environment. Relative to those without readmissions, readmitted patients had higher in-hospital mortality rates, shorter long-term survival, poorer quality of life, longer hospital stay, increased recurrence of subsequent readmissions, and accounted for greater healthcare costs. The second part of this thesis describes a five-year longitudinal retrospective study that utilised administrative hospital data from all four public hospitals in Tasmania. Patients ‚Äöv¢‚Ä¢40 years of age who had overnight COPD-related hospitalisation between 2011 and 2015 were followed up for 12 months post-index discharge. The study investigated the prevalence of hospital readmission for COPD at 30 days, 90 days and 12 months, and determined the risk factors for 30-day and 90-day readmission and time to COPD-related readmission within 12 months. Factors associated with readmission were identified using logistic and Cox regression. The rates of COPD-related readmission were 6.7% within 30 days, 12.2% within 90 days and 23.7% within 12 months. Being male (OR 1.49, 95% CI 1.06‚Äö-2.09), Indigenous (OR 2.47, 95% CI 1.31‚Äö-4.66) and living in the low socioeconomic North-West region (OR 1.80, 95% CI 1.20‚Äö-2.69) were significant risk factors for 30-day readmission. Increased COPD-related (OR 1.48, 95% CI 1.22‚Äö-1.80; OR 1.52, 95% CI 1.29‚Äö-1.78) and non-COPD-related (OR 1.12, 95% CI 1.03‚Äö-1.23; OR 1.11, 95% CI 1.03‚Äö-1.21) Emergency Department (ED) visits in the previous six months were significant risk factors for 30-day and 90-day readmissions. Being Indigenous (HR 1.61, 95% CI 1.10‚Äö-2.37) and increased COPD-related ED visits in the previous six months decreased the time to readmission within 12 months (HR 1.30, 95% CI 1.21‚Äö-1.39), while a higher Charlson Comorbidity Index increased time to readmission (HR 0.91, 95% CI 0.83‚Äö-0.99). In conclusion, the thesis summarised that hospitalisation in the previous year was the key predictor for COPD-related readmission reported in studies. Due to the differences in the reported factors associated with COPD-related readmissions, these factors should be considered in the light of locality due to variations in healthcare systems around the world. Some patient factors (being male, Indigenous, living in the lower socioeconomic North-West region) and system factors (recent ED visits) were identified to be associated with increased risk of COPD readmission in Tasmania. The present work has the following public health implications. Males, Indigenous people, having recent ED visits and those in the lower socioeconomic areas are at increased risk of COPD-related readmission in Tasmania. Sustainable interventions (e.g. smoking cessation, education) directed at these people may avert and lessen COPD-related readmission. Embarking on community support frameworks that improve their access to health care may eradicate the barriers that influence the way they interact with healthcare system. Improving access to healthcare professionals within the communities, especially in the low socioeconomic areas, may also improve health outcomes, reduce ED visits and readmissions.