Quality of care and clinical outcomes of chronic obstructive pulmonary disease in patients with schizophrenia. A Danish nationwide study

Objective: To examine the association between schizophrenia and the quality of care and clinical outcomes of chronic obstructive pulmonary disease (COPD).

Design: A Danish nationwide population-based cohort study using comprehensive information from Danish registries between 2008 and 2013.

Setting: Public Danish hospitals.

Participants: 72 692 COPD patients with hospital contacts including 621 with schizophrenia.

Intervention: COPD care.

Main Outcome Measures: The quality of COPD care was defined as meeting guideline-recommended process performance measures of care. Potential predictors of COPD care among patients with schizophrenia included patient- (sex, age, alcohol or drug abuse, Global Assessment of Functioning score, duration of schizophrenia), provider- (quality of schizophrenia care), and system-related factors (contact-volume defined as hospital department and clinics' annual average contact volume of COPD patients). Clinical outcomes included 30-day all-cause readmission and 30-day all-cause mortality risk following an admission for exacerbation of COPD.

Results: Compared to COPD patients without schizophrenia, COPD patients with schizophrenia had a lower chance of receiving treatment with long-acting muscarinic antagonists (LAMA) or long-acting β2-agonists (LABA) (Relative risk (RR) 0.92, 95% CI: 0.87-0.98). Female sex was associated with a higher chance of receiving LAMA/LABA treatment among COPD patients with schizophrenia. COPD patients with schizophrenia had a higher risk of 30-day mortality (adjusted odds ratio (OR) 1.27, 95% CI: 1.01-1.59) but not a higher risk of readmission compared with COPD patients without schizophrenia.

Conclusions: COPD patients with schizophrenia had a slightly lower chance of receiving LAMA/LABA treatment, but a substantially increased risk of death following admission for an exacerbation compared with patients without schizophrenia.