Community-acquired pneumonia; epidemiology and recovery
Publication Date
July 19, 2023
Creator
Abstract
Lower respiratory tract infections (LRTIs) represent a spectrum of disease ranging from acute bronchitis to severe community-acquired pneumonia (CAP) and are responsible for 3.2million deaths per year worldwide. Community-acquired pneumonia affects approximately 1% of the UK adult population, with over 100,000 admissions to hospital. Direct healthcare costs are estimated between £441 million and £765 million per year.
Streptococcus pneumoniae is the most frequently identified pathogen in patients with CAP, being directly or indirectly detected in 50% of CAP cases. Streptococcus pneumoniae is an encapsulated gram-positive coccus, with variation in the polysaccharide capsule responsible for differentiation in to more than 90 serotypes. Vaccination programmes against streptococcus pneumoniae have been implemented worldwide to reduce the morbidity and mortality associated with pneumococcal infection. Between 2013 and 2018 a prospective cohort study of adults admitted to a large teaching hospital was conducted, with reference to determining serotype prevalence and clinical risk factors for cases of both invasive and non-invasive pneumococcal disease. Pneumococcal serotype was established using a novel, validated multiplex immunoassay on urine samples that targeted 24 pneumococcal serotypes and cell wall polysaccharide, in combination with blood culture serotype results. During the study period the PCV7 vaccine was replaced by PCV13 vaccine. The results highlighted serotype shift in response to vaccine pressure, with increasing prevalence of non-vaccine serotypes in both invasive and non-invasive pneumococcal disease, as well as deviation away from traditional ‘at risk’ cohorts. The study concludes that an up-to-date understanding of prevailing pneumococcal serotypes and the associated ‘at risk’ populations are fundamental to inform vaccine development, immunisation policy, and clinical practice.
Most of the research in CAP has focussed on timely and accurate diagnosis, optimal management, and risk prediction for traditional outcomes such as mortality and readmission. It has been demonstrated that the majority of patients admitted to hospital with an episode of CAP survive their admission and are discharged to recover in the community. There is a paucity of evidence in the recovery phase, but the available studies highlight a substantial burden of disease for patients during this recovery phase. This thesis aimed to highlight the burden of disease experienced by patients during recovery, develop a consensus on the appropriate tools to employ in future studies of CAP recovery, and explore the feasibility of a specific intervention to improve recovery.
A qualitative study, utilising semi-structured interviews with patients and healthcare providers, to provide a rich description of their ideas, concerns, and experiences of a diagnosis of CAP, its treatment and the associated recovery journey is reported. The study reported that patients were unprepared for the substantial morbidity associated with CAP, consequentially experienced a high degree of anxiety, and frequently re-consulted healthcare providers due to unmet psychosocial needs. Furthermore, healthcare professionals were unaware of the substantial burden that patients experienced and under-appreciated the psychosocial impact of CAP on patients.
Chapters 4 and 5 present the findings of two systematic reviews, conducted according to PRISMA guidelines. The first systematic review outlines patient-reported outcome measures in patients in recovering following hospitalisation for CAP. Patient-reported outcome measures are increasingly recognised as important endpoints in trials and have been recommended for use in studies of drug development. The review demonstrates that a substantial proportion of patients report symptomatic and functional impairments during the first 6 weeks following discharge. The prevalence of symptoms varies across studies in accordance with severity of CAP and age of study cohorts. Persistent symptoms and functional impairment are associated with adverse impacts on the performance of ‘normal activities’, such as return to work, and healthcare utilisation.
The second systematic review reports 30-day readmission rates and associated risk factors following an episode of hospitalised CAP. Readmission rates have been adopted as surrogate markers of clinical care, but there is limited evidence to determine how and if 30-day readmission rates can be compared within and across different healthcare systems. Thirty-day readmission rate was estimated to be 10% across all included studies. Variation in 30-day readmission was observed by geographic location, whilst estimates of 30-day readmission rate were significantly higher in large database and retrospective studies. Readmissions within 30-days were predominantly pneumonia unrelated, with cardiovascular events accounting for 20% of readmissions. Co-morbid disease, socio-economic status, and clinical instability at point of discharge were identified as risk factors associated for 30-day readmission.
Given the substantial burden of disease highlighted in the preceding studies, two prospective studies were undertaken at a large teaching hospital in UK.
The first study aimed to determine the tolerability, acceptability, and suitability of individual tools, in different clinically important domains, for the measurement of different aspects of recovery following an episode of hospitalised CAP. Overall, participants demonstrated an improvement in their symptoms, functional ability, and physical capacity from discharge to follow-up at 42-days. The employed assessments demonstrated variable tolerability and acceptability to patients. Questionnaires demonstrated the highest levels of tolerability and acceptability, regardless of whether conducted in-person or remotely. In contrast, assessments of exercise capacity and lung function, requiring attendance at hospital, were less tolerable in the initial days following discharge, with increasing acceptability and tolerability with time from discharge.
The second study sought to determine the safety, tolerability, and acceptability of using an inspiratory muscle training device in the recovery phase of CAP. The study reports that IMT following an episode of CAP was acceptable and tolerable, with side-effects related to IMT were low severity and infrequent, but IMT efficacy is still to be determined.
The thesis highlights the requirement for additional studies in CAP recovery, an area with a substantial paucity of research or evidence on which to base clinical management. These studies should seek to define normal recovery in a large cohort of patients, to derive and validate risk assessment to predict impaired recovery and determine potential targets for novel interventions to alleviate the burden of disease and expedite recovery. Future studies should combine the current knowledge from studies of CAP recovery with the available evidence in recovery following COVID-19 infection.
Item Type
ethesis
Thesis Type
PhD
Subjects (LC)
Associated Schools / Departments
School of Medicine
eprints ID
72337
UoN Repository URI
Except where otherwise noted, this item's license is described as
File(s)![Thumbnail Image]()
Name
PhD Thesis - Harry Pick - 4291509 - Janury 2023 (corrections_final).pdf
Type
Full-text
Description
Examined. Thesis with corrections
Size
3.54 MB
Format
Adobe PDF
Checksum (MD5)
446799bf9413ec00abc0f707bb265ac1