Trends in moderate and severe exacerbations among COPD patients in the UK from 2005 to 2013

Introduction: Exacerbations of chronic obstructive pulmonary disease are characterised by increased symptoms such as dyspnoea, cough and sputum production and/or purulence, leading to greater risk of hospitalisation and mortality. Very few studies have measured long term trends in the incidence of exacerbations of chronic obstructive pulmonary disease. We therefore investigated the incidence of moderate and severe exacerbations in the UK general population.

Methods: A population based-study including Clinical Practice Research Datalink (CPRD) patients >= 40 years of age with a current diagnosis of COPD within the United Kingdom from 2004 to 2013 was conducted. Individuals with a history of asthma were excluded from main analyses. We calculated the incidence rates for any, moderate, and severe exacerbations. Patients contributed time at risk from January 1st up to the date of the first outcome within each year. The incidence rate for any, moderate and severe exacerbations for COPD in each calendar year was calculated as follows: the sum of any or moderate or severe exacerbations for COPD in that year divided by the total duration of follow-up in the same calendar year from 2005 through to 2013. We then analysed these rates by gender and age categories (40-59 years, 60-79 years and >= 80 years).

Results: Among 213,561 with incident COPD diagnosis, 86,300 patients were included in the study. From 2005 to 2013, the incidence rate of any exacerbations increased from 89 to 98 per 1000 person years (PYs) (p = 0.005). Women had significantly higher incidence rates of any exacerbation for each calendar year when compared to men (p <0.0001). The incidence rate of any and moderate exacerbations increased with age from 2005 to 2007. For severe exacerbations incidence decreased from 2005 to 2007 before increasing from 2008 until the end of follow-up (43 per 1000 PYs (95% confidence interval, 42-45/1000PYs) in 2013). Incidence rates of severe exacerbations were similar by gender and patients aged 80 + years had a higher incidence rate of severe exacerbation from 2005 to 2008 after which their incident rate dropped in subsequent years.

Conclusion: This is the first study that reports the long-term changes in the incidence rates of moderate and severe exacerbations within the UK general practice. Women showed a substantially higher risk of any COPD exacerbations, and their risk is increasing. The incidence rates of any exacerbations increased during the study period, while severe exacerbations were variable. Furthermore, incidence rates varied substantially by age group.