Lindenauer PK, Shieh MS, Stefan MS, Fisher KA, Haessler SD, Pekow PS, Rothberg MB, Krishnan JA, Walkey AJ. Hospital Procalcitonin Testing and Antibiotic Treatment of Patients Admitted for Chronic Obstructive Pulmonary Disease Exacerbation. Ann Am Thorac Soc. 2017 Dec; 14(12):1779-1785.