Changing incidence of pneumonia diagnosis in UK primary care from 2002-2017: Population-based cohort study

Background: Increasing hospital admissions for pneumonia have been reported but it is not known whether pneumonia diagnoses have increased in the community. Objectives: To determine whether diagnosis of pneumonia increased in primary care in the United Kingdom from 2002 to 2017. Methods: An open cohort study over 16 years was conducted using electronic health records from the UK Clinical Practice Research Datalink (CPRD). Diagnoses tends of bacterial pneumonia, influenza pneumonia, pleural infection and chest infection treated with antibiotics were fitted into jointpoint regression model and estimated by annual percentage changes (APC). Results: The incidence of pneumonia diagnosis increased from 1.50 per 1,000 person-years in 2002 to 2.22 per 1,000 in 2017. From 2010 to 2017, the APC in age-standardised incidence was 5.1% (95% confidence interval, 3.4 to 6.9%) compared to 0.3% (-0.6 to 1.2%) before 2010. Chest infection treated with antibiotics increased from 2002 to 2008 with an APC 3.8% (0.8 to 6.9%) but decreased by an APC -4.9% (-6.7 to -3.1%) from 2009 to 2017. Influenza pneumonia increased in the epidemic year of 2009. There was no overall trend in pleural infections. Conclusion: This analysis reveals a recent increase in pneumonia diagnosis in primary care but a contemporaneous decline in that of chest infection suggests that changes in disease labelling practice might partly account for this trend.