Relation of Low Lymphocyte Count to Frailty and its Usefulness as a Prognostic Biomarker in Patients >65 Years of Age With Acute Coronary Syndrome

Abstract

Low lymphocyte count, as a marker of inflammation and immunosuppression, may be useful for identifying frail patients. In this work, we aimed to evaluate the association between low-relative lymphocyte count (Lymph%) and frailty status in patients >65 years old with acute coronary syndromes (ACS), and whether Lymph% is associated with morbimortality beyond standard prognosticators and frailty. In this prospective observational study, we included 488 hospital survivors of an episode of an ACS >65 years old. Total and differential white blood cells and frailty status were assessed at discharge. Frailty was evaluated using the Fried score at discharge and defined as Fried≥3. The independent association between Lymph% and Fried≥3 was evaluated by multivariate logistic regression analysis. The associations between Lymph% with long-term all-cause mortality and recurrent admission were evaluated with Cox regression and shared frailty regression, respectively. The mean age of the sample was 78 ± 7 years and 41% were females. The median (interquartile range) of the Lymph% was 21% (15 to 27) and 41% showed Fried≥3. In multivariate analysis, Lymph% was inversely related to the odds of frailty with an exponential increase risk from values below 15% (p = 0.001). Likewise, Lymph% was inverse and independently associated with a higher risk of long-term mortality (p = 0.011), recurrent all-cause (p = 0.020), and cardiovascular readmissions (p = 0.024). In conclusion, in patients >65 years with a recent ACS, low Lymph% evaluated at discharge is associated with a higher risk of frailty. Low Lymph% was also associated with a higher risk of long-term mortality and recurrent admissions beyond standard prognosticators and Fried score.