Low Relative Lymphocyte Count Associated With Higher Mortality in COPD

Low relative lymphocyte count was associated with poor prognosis in elderly patients with severe chronic obstructive pulmonary disease (COPD), according to a study published in the BMC Pulmonary Medicine. Although the inherent mechanisms of lymphopenia should be further investigated, relative lymphocyte counts had a strong effect on all-cause mortality.

Present studies have defined efforts to detect new prognostic markers to stratify mortality risk associated with patients with COPD. This 3-year prospective study sought to assess the role of relative lymphocyte count in predicting long-term all-cause mortality in elderly patients diagnosed with COPD.

The study sample included a total of 218 patients (104 women and 114 men) with moderate to severe COPD who were recruited from the Institute of Care and Scientific Research related to Cardiac and Pulmonary Rehabilitation in Benevento, Italy. The mean age of participants was 75.2±7 years, and all patients were determined free of comorbid conditions affecting lymphocyte count. The sample was divided into 2 groups: 85 patients with a relative lymphocyte count ≤20% and 133 patients with a relative lymphocyte count >20%.

Baseline data were collected for all patients within a week of hospitalization, including clinical history and physical evaluation measures (complete blood count, lung function, arterial blood gas analysis, and electrocardiogram). Follow-up occurred at 6, 12, 24, and 36 months after patients were discharged from the hospital; the primary study end point was all-cause death.

Study results indicated 3-year mortality rates (from any cause) of 68% for patients with a relative lymphocyte count ≤20% and 51% for patients with a relative lymphocyte count >20% (P =.0012). Patients with low relative lymphocyte counts had significantly lower lung function indices and a greater prevalence of congestive heart failure, diabetes, and chronic cor pulmonale. Mortality in patients with relative lymphocyte counts ≤20% was also higher in the survival curve analysis. Adjusting for age and gender, a hazard ratio of 1.79 (95% CI, 1.22-2.62; P =.003) was calculated according to lymphocyte count, and risk for death was consistent when limited to participants without congestive heart failure (n=171; P =.038).

Limitations of the study included a lack of data determining the cause of death in participants and not accounting for certain complications of severe COPD that simulate congestive heart failure. Specific subpopulations of lymphocytes were not measured, further limiting the study.

A low relative lymphocyte count at baseline was significantly associated with severe chronic illnesses (including COPD) and an increased incidence of death from any cause. Even though the mechanisms leading to lymphopenia are still unclear, the authors of the study suggest that relative lymphocyte count is a valuable indicator of health status.

Reference

Acanfora D, Scicchitano P, Carone M, et al. Relative lymphocyte count as an indicator of 3-year mortality in elderly people with severe COPD. BMC Pulm Med. 2018;18(1):116. doi:10.1186/s12890-018-0685-6