Background Although there appears considerable burden from cognitive impairment in people with COPD, much less information is available about diagnosed dementia in patients with COPD.

Objective To determine the prevalence and incidence of dementia in patients with and without COPD in the UK using the electronic health record: The Health Improvement Network (THIN) database.

Materials and methods A matched case control and cohort study design using THIN were conducted. Patients with an incident COPD diagnosis, aged over 40 years old were matched by age, gender, and GP practice to up to 4 subjects without a COPD diagnosis. READ codes defined a dementia diagnosis. Multivariable conditional logistic regression was performed to calculate the odds ratio (OR) for the prevalence of dementia. Cox proportional hazard model was used to assess the effect of COPD on the risk of dementia. Results were adjusted for confounders.

Results A total of 65 068 patients with COPD and 2 49 166 matched non-COPD subjects were included. Overall, 4914 subjects (1.56%) had a coded dementia diagnosis. Prevalence of dementia was less in patients with COPD compared to non-COPD subjects, adjusted Odd Ratio (aOR), 0.75; 95% confidence interval [CI] 0.65–87; p<0.001. The incidence of coded dementia following COPD diagnosis (n=64,280) was less than in non-COPD subjects following the index date (n=242,605), adjusted Hazard Ratio (aHR), 0.87, 95% CI 0.78–0.97, p=0.019.

Conclusion Prevalence at COPD diagnosis and incidence of coded dementia in patients with COPD was less than a matched population without COPD. Despite the reported greater proportion of patients with cognitive impairment, the fact dementia diagnosis is reported less frequently than a matched non-COPD population requires consideration.