ADRB2 and chronic obstructive pulmonary disease: The RR of using NRT between those exposed and those unexposed to β2AR agonists was reduced from 2.62 (95% CI: 2.59, 2.66; p<.001) to 1.38 (95% CI: 1.36, 1.41; p<.001) after adjusting for educational level, comorbidity, and excluding COPD patients.