• Marilyn L Moy, Merilee Teylan, Valery A Danilack, David R Gagnon, and Eric Garshick.
• 1 Department of Veteran's Affairs, Veterans Health Administration, Rehabilitation Research and Development Service.
• Ann Am Thorac Soc. 2014 Feb 1;11(2):149-57.

BackgroundIdentification of persons with chronic obstructive pulmonary disease (COPD) at risk for acute exacerbations (AEs) targets them for close monitoring.ObjectivesWe examined the ability of a novel index combining physical activity and systemic inflammation to identify persons at risk for AEs.MethodsIn an observational cohort study of 167 persons with COPD, we assessed daily step count, a direct measure of physical activity, with the StepWatch Activity Monitor and measured plasma C-reactive protein (CRP) and IL-6 levels. AEs and COPD-related hospitalizations were assessed prospectively over a median of 16 months. Predictors of AEs and COPD-related hospitalizations were assessed using negative binomial models.Measurements And Main ResultsMedian daily step count was 5,203 steps (interquartile range, 3,627-7,024). Subjects with daily step count ≤ 5,203 and CRP > 3 mg/l had an increased rate of AEs (rate ratio [RR], 2.06; 95% confidence interval [CI], 1.30-3.27) and COPD-related hospitalizations (RR, 3.51; 95% CI, 1.73-7.11) compared with subjects with daily step count > 5,203 and CRP ≤ 3 mg/l, adjusting for FEV1% predicted and prednisone use for AE in the previous year. Similarly, subjects with daily step count ≤ 5,203 and IL-6 > 2 pg/ml had an increased rate of AEs (RR, 2.04; 95% CI, 1.14-3.63) and COPD-related hospitalizations (RR, 4.27; 95% CI, 1.56-11.7) compared with subjects with daily step count > 5,203 and IL-6 ≤ 2 pg/ml.ConclusionsAn index combining daily step count and systemic inflammation can predict AEs and COPD-related hospitalizations. A validation study in a separate cohort is needed to confirm the utility of the proposed index as a clinical tool to risk stratify persons with COPD.

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