- Woodruff, Prescott;
- Freeman, CM;
- Crudgington, S;
- Stolberg, VR;
- Brown, JP;
- Sonstein, J;
- Alexis, NE;
- Doerschuk, CM;
- Basta, PV;
- Carretta, EE;
- Couper, DJ
© 2015 Freeman et al.; licensee BioMed Central.Background: Subpopulations and Intermediate Outcomes in COPD Study (SPIROMICS) is a multi-center longitudinal, observational study to identify novel phenotypes and biomarkers of chronic obstructive pulmonary d