Xiong XF, et al. - In this randomized controlled trial, researchers assessed the effects of tiotropium and low-dose theophylline (200 mg/day) on stable chronic obstructive pulmonary disease (COPD) patients of groups B and D. Study participants included 170 patients who were randomized to receive either 18 μg tiotropium once daily for 6 months with theophylline 100 mg twice daily (Group I) or 18 μg tiotropium once daily (Group II). After 6 months of follow-up, tiotropium plus low-dose theophylline substantially improved the symptoms and general health of patients with stable COPD of groups B and D. In addition, this treatment also improved small airway function indicators.