Identifying the associated risks of pneumonia in COPD patients: ARCTIC an observational study

Background Inhaled corticosteroids (ICS) are associated with an increased risk of pneumonia in patients with chronic obstructive pulmonary disease (COPD). Other factors such as severity of airflow limitation and concurrent asthma may further raise the possibility of developing pneumonia. This study assessed the risk of pneumonia associated with ICS in patients with COPD. Methods Electronic Medical Record data linked to National Health Registries were collected from COPD patients and matched reference controls in 52 Swedish primary care centers (2000–2014). Levels of ICS treatment (high, low, no ICS) and associated comorbidities were assessed. Patients were categorized by airflow limitation severity. Results A total of 6623 patients with COPD and 48,566 controls were analyzed. Patients with COPD had a more than 4-fold increase in pneumonia versus reference controls (hazard ratio [HR] 4.76, 95% confidence interval [CI]: 4.48–5.06). ICS use increased the risk of pneumonia by 20–30% in patients with COPD with forced expiratory volume in 1 s ≥ 50% versus patients not using ICS. Asthma was an independent risk factor for pneumonia in the COPD population. Multivariate analysis identified independent predictors of pneumonia in the overall population. The highest risk of pneumonia was associated with high dose ICS (HR 1.41, 95% CI: 1.23–1.62). Conclusions Patients with COPD have a greater risk of pneumonia versus reference controls; ICS use and concurrent asthma increased the risk of pneumonia further.