Serum levels of IGFBP7 are elevated during acute exacerbation in COPD patients

OBJECTIVE: The purpose of this study was to explore the insulin-like growth factor binding protein 7 (IGFBP7) level in the serum of chronic obstructive pulmonary disease (COPD) patients during acute exacerbation (AE). METHODS: The study population consisted of 47 AECOPD patients, including 25 patients enrolled between January 2011 and February 2011 (the first group) and 22 patients enrolled from December 2011 to August 2012 (the second group) and 29 healthy controls. Chemiluminescence–linked immunoassay was used to detect serum IGFBP7 levels. For the second group patients, IGFBP7 and C-reactive protein (CRP) levels were measured both on the admission day and on the discharge day. RESULTS: Among the first group AECOPD patients, serum IGFBP7 levels were significantly elevated in AECOPD patients in the intensive care unit (ICU; 52.92±16.32 ng/mL), and in hospitalized AECOPD patients not in ICU (40.66±13.9), compared to healthy subjects (30.3±7.09 ng/mL; P<0.01). For the second group AECOPD patients, the increased IGFBP7 levels reduced after the patients had recovered (34.42±11.88 vs 27.24±7.2 ng/mL; P<0.01). During AE, the correlation coefficient between IGFBP7 and CRP was 0.357. In receiver operating characteristic analysis, the area under the curve was 0.799 for CRP, and 0.663 for IGFBP7 in distinguishing patients with AECOPD on the admission day from the discharge day. CONCLUSION: Serum IGFBP7 levels were raised during AECOPD. Similar to the expression pattern of CRP, the IGFBP7 levels reduced after convalescence, suggesting that IGFBP7 might have a candidate role as a biomarker of AECOPD. No significant linear correlation was detected between IGFBP7 and CRP, indicating the probable different role for the two molecules in assessing AECOPD. Further study is needed to explore the value of IGFBP7 in differentiating phenotypes of AECOPD.