Seasonality, risk factors and burden of community-acquired pneumonia in COPD patients: a population database study using linked health care records.
BACKGROUND
Community-acquired pneumonia (CAP) is more common in patients with COPD than in the adult general population, with studies of hospitalized CAP patients consistently reporting COPD as a frequent comorbidity. However, despite an increasing recognition of its importance, large studies evaluating the incidence patterns over time, risk factors and burden of CAP in COPD are currently lacking.


METHODS
A retrospective observational study using a large UK-based database of linked primary and secondary care records was conducted. Patients with a diagnosis of COPD aged ≥40 years were followed up for 5 years from January 1, 2010. CAP and exacerbation episodes were identified from hospital discharge data and primary care coding records, and rates were calculated per month, adjusting for mortality, and displayed over time. In addition, baseline factors predicting future risk of CAP and hospital admission with CAP were identified.


RESULTS
A total of 14,513 COPD patients were identified: 13.4% (n=1,938) had ≥1 CAP episode, of whom 18.8% suffered from recurrent (≥2) CAP. Highest rates of both CAP and exacerbations were seen in winter. A greater proportion of frequent, compared to infrequent, exacerbators experienced recurrent CAP (5.1% versus 2.0%, respectively,P<0.001); 75.6% of CAP episodes were associated with hospital admission compared to 22.1% of exacerbations. Older age and increasing grade of airflow limitation were independently associated with increased odds of CAP and hospital admission with CAP. Other independent predictors of future CAP included lower body mass index, inhaled corticosteroid use, prior frequent exacerbations and comorbidities, including ischemic heart disease and diabetes.


CONCLUSIONS
CAP in COPD demonstrates clear seasonal patterns, with patient characteristics predictive of the odds of future CAP and hospital admission with CAP. Highlighting this burden of COPD-associated CAP during the winter period informs us of the likely triggers and the need for more effective preventive strategies.
Southampton NIHR Respiratory Biomedical Research Unit, Southampton General Hospital; Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital.
Nicholas P
NP
Williams
Primary Care and Population Sciences, Faculty of Medicine, Southampton General Hospital.
Ngaire A
NA
Coombs
NIHR CLAHRC Wessex, Faculty of Health Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
Matthew J
MJ
Johnson
Primary Care and Population Sciences, Faculty of Medicine, Southampton General Hospital; NIHR CLAHRC Wessex, Faculty of Health Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
Lynn K
LK
Josephs
Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital; NIHR CLAHRC Wessex, Faculty of Health Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
Lucy A
LA
Rigge
Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital.
Karl J
KJ
Staples
Southampton NIHR Respiratory Biomedical Research Unit, Southampton General Hospital; Primary Care and Population Sciences, Faculty of Medicine, Southampton General Hospital; NIHR CLAHRC Wessex, Faculty of Health Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
Mike
M
Thomas
Southampton NIHR Respiratory Biomedical Research Unit, Southampton General Hospital; Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital; NIHR CLAHRC Wessex, Faculty of Health Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
Tom Ma
TM
Wilkinson
D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D016009:Chi-Square Distribution; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D015897:Comorbidity; D016208:Databases, Factual; D018450:Disease Progression; D057286:Electronic Health Records / Q000639:trends; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008168:Lung / Q000503:physiopathology; D008297:Male; D008498:Medical Record Linkage; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010359:Patient Readmission / Q000639:trends; D011014:Pneumonia / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D013997:Time Factors; D006113:United Kingdom
D000305:Adrenal Cortex Hormones
COPD exacerbations; community-acquired pneumonia; comorbidity; exacerbation frequency