PURPOSE: Pneumonia is a common, serious and potentially life-threatening disease, yet its natural history in COPD patients is not well studied in population-based cohorts. We designed a study in the General Practice Research Database (GPRD), an automated medical records database representative of the UK population, to (1) quantify the incidence of community-acquired pneumonia (CAP) in a COPD cohort from 1996 to 2005, and (2) evaluate risk factors for CAP.
METHODS: The study population consisted of patients aged 45 years and older with a COPD diagnosis between 1996 and 2005, and at least one respiratory medication within 12 months of the first COPD diagnosis, and at least one year of data before and after incident COPD diagnosis. The outcome of interest was defined by diagnosis codes consistent with CAP and without confirmation of chest x-ray. Incidence rates were calculated using person-time at risk. To model risk factors for CAP, two cohorts were created: each patient with at least one CAP episode recorded after COPD incident diagnosis was matched to at least five patients with no CAP event and a similar length of follow-up in the database. Logistic regression models were conducted to estimate odds ratios and 95% confidence intervals for factors associated with CAP.
RESULTS: In a COPD cohort of 40,414 patients, the incidence density of community-acquired pneumonia was 22.4 per 1,000 person-years (95% C 21.7 to 23.2). Increased risk for CAP was associated with severe COPD exacerbation requiring hospitalization (OR=2.74, 95%CI: 2.33, 3.21), and moderate COPD exacerbation (OR=1.28, 95%CI: 1.13, 1.46) in the 12 months prior to the pneumonia episode. Pneumonia risk was also increased with comorbid conditions: dementia (OR=2.64, 95%CI, 1.86, 3.74), CHF (OR=1.37, 95%CI: 1.20, 1.57), peripheral vascular disease (OR=1.27, 95%CI: 1.05, 1.54) and peptic ulcer (OR=1.22, 95%CI: 1.06, 1.40).
CONCLUSION: Community acquired pneumonia episodes were relatively frequent in COPD patients treated in UK general practice and associated with disease severity and comorbid conditions.
CLINICAL IMPLICATIONS: COPD patients should be monitored for pneumonia risk, particularly as severity increases.
DISCLOSURE: Kourtney Davis, No Product/Research Disclosure Information; Employee I am a fulltime employee of GSK R&D