Acute coronary syndrome (heart attacks and unstable angina) and chronic obstructive pulmonary disease (COPD) are among the commonest reasons for hospital admission and death in New Zealand. Māori, Pacific peoples, and lower income groups are particularly affected. Acute coronary syndrome is common among people with COPD. Inhaled long-acting bronchodilators (long-acting muscarinic antagonists [LAMAs] and long-acting beta-agonists [LABAs]) are the main drugs used to treat people with COPD. However, there is concern that both LAMAs and LABAs may further increase the risk of acute coronary syndrome. This is important because the clinical benefits of these drugs are modest and people with COPD are more likely to die from coronary events than from respiratory failure. We propose to undertake a study to determine the risk of acute coronary events in people taking LAMAs and LABAs. The study will use anonymised existing data only, no patients will be approached.