C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) as inflammation markers in elderly patients with stable chronic obstructive pulmonary disease (COPD)

Abstract

Erythrocyte sedimentation rate (ESR) might represent a less expensive alternative to C-reactive protein (CRP) as a marker of systemic inflammation in stable chronic obstructive pulmonary disease (COPD). We tried to verify this hypothesis in 223 consecutive outpatients aged 65 years or more with stable COPD enrolled in a multicenter observational study. Patients were grouped according to normal/increased ESR/CRP values and groups were compared with regard to clinical and laboratory characteristics. Correlations between CRP, ESR and selected variables of interest were assessed by Spearman's zeta-test and multivariate linear regression analysis. CRP was weakly and inversely correlated with the forced expiratory volume in the first second (FEV1%) (Spearman's zeta=-0.15; p<0.027), while ESR was not (Spearman's zeta=-0.05; p=0.411). The highest prevalence of anemia and hypoalbuminemia and the lowest FEV1% were recorded in high ESR-high CRP group. For anemia B=14.180+/-3.521 (+/-S.E.M.); p=0.001 and hypoalbuminemia B=10.241+/-3.790; p=0.007 qualified as significant independent correlates of ESR values, while only FEV1 remained significantly associated with CRP values (B=-0.570+/-0.258; p=0.028). In conclusion, CRP, but not ESR, shows a weak correlation with COPD severity, while anemia and hypoalbuminemia are main correlates of high ESR. Neither ESR, nor CRP qualify as reliable markers of COPD severity and seem to reflect the effects of different determinants.