1Center for Primary Care and Outcomes Research, Stanford, University, Stanford, California, USA
2VA Palo Alto Health Care System, Palo Alto, California, USA; Stanford University Medical Center, Palo Alto, California, USA; Center for Primary Care and Outcomes Research, Stanford University, Stanford, California, USA
Correspondence to: Dr J-E C Holty Division of Pulmonary and Critical Care Medicine, University School of Medicine, 300 Pasteur Drive, H3143, Stanford, CA 94305-5236, USA; [email protected]
Competing interests: None declared.
