Chronic obstructive pulmonary disease hospital admissions and drugs—unexpected positive associations: a retrospective general practice cohort study

BACKGROUND: Increased prescribing of inhaled long-acting anti-muscarinic (LAMA) and combined inhaled long-acting β(2)-agonist and corticosteroid (LABA+ICS) drugs for the treatment of chronic obstructive pulmonary disease (COPD) has led to hopes of reduced hospital admissions from this disease. AIMS: To investigate the impact of rising primary care prescribing of LAMA and LABA+ICS drugs on COPD admissions. METHODS: This retrospective cohort study of general practice COPD admission and prescribing data between 2007 and 2010 comprised a representative group of 806 English general practices (population 5,264,506). Outcome measures were practice rates of COPD patient admissions and prescription costs of LAMA and LABA+ICS. General practice characteristics were based on the UK quality and outcomes framework. RESULTS: Rates of COPD admissions remained stable from 2001 to 2010. Practice-prescribing volumes of LAMA per practice patient and LABA+ICS per practice patient increased by 61 and 26%, respectively, between 2007 and 2010. Correlation between costs of LAMA and those of LABA+ICS increased year on year, and was the highest in 2010 (Pearson’s r=0.68; 95% confidence interval (CI), 0.64–0.72). Practice COPD admission rates were positively predicted by practice-prescribing volumes of LAMA (2010: B=1.23, 95% CI, 0.61–1.85) and of LABA+ICS (2010: B=0.32, 95% CI, 0.12–0.52) when controlling for practice list size, COPD prevalence and deprivation. CONCLUSION: The increase in the prescribing of LAMA and LABA+ICS inhalers was not associated with the predicted fall in hospital admission rates for COPD patients. The positive correlation between high practice COPD prescribing and high practice COPD admissions was not explained.