Relative lymphocyte count as an indicator of 3-year mortality in elderly people with severe COPD

Background: Prognostic stratification of elderly patients with chronic obstructive pulmonary disease (COPD) is difficult due to the wide inter-individual variability in the course of the disease. No marker can exactly stratify the evolution and natural history of COPD patients. Studies have shown that leukocyte count is associated with increased risk of mortality in COPD patients. The aim of this study was to evaluate the possible role of relative lymphocyte count as a risk marker for mortality in elderly patients with COPD. Methods and results: This is a3-year prospective study. A total of 218patients, mean age 75.2 +/- 7 years, with moderate to severe COPD and free from conditions affecting lymphocyte count were enrolled. The population was divided into two groups according to the relative lymphocyte count, with a cut-off of 20%. Eighty-five patients (39%) had a relative lymphocyte count <= 20%. Three-year mortality rates from any cause in patients with relative lymphocyte count <= or > 20% were 68 and 51%, respectively (p = 0.0012). Survival curve analysis showed higher mortality in patients with relative lymphocyte count <= 20% (p = 0.0005). After adjustment for age and sex, the hazard ratio for mortality risk according to lymphocyte count was 1.79 (95% confidence interval [CI]: 1.26-2.57, p = 0.0013), even in the analysis limited to the 171 patients without congestive heart failure (1.63; 95% CI: 1.03-2.58, p = 0.038). Conclusions: Low relative lymphocyte count was associated with higher mortality in elderly patients with severe COPD.