Fig. 1From: Prevention of exacerbations in patients with COPD and vitamin D deficiency through vitamin D supplementation (PRECOVID): a study protocolFlowchart of study procedures during the PRECOVID trial. Randomisation will take place within 6-8 weeks after an exacerbation. During the study period of one year three study visits and four telephone contacts will take place. MIP: Maximal inspiratory pressure; MEP: Maximal expiratory pressure; TLC: Total lung capacityBack to article page