Association of chronic neutrophil activation with risk of mortality

BACKGROUND: Levels of free myeloperoxidase (MPO), a cardiovascular risk marker, have been reported to decline with standard care. Whether such declines signify decreased risk of mortality remains unknown. DESIGN: Cox proportional hazard models were generated using data from a retrospective cohort study of prospectively collected measures. PARTICIPANTS: Patients (3,658) who had MPO measurements and LDL-C ≥ 90 mg/dL during 2011–2015 were selected based on a stratified random sampling on MPO risk level. Baseline MPO was either low (<470 pmol/L), moderate (470–539 pmol/L), or high (≥540 pmol/L). MAIN OUTCOMES AND MEASURES: First occurrence of MACE (myocardial infarction, stroke, coronary revascularization, or all-cause death). RESULTS: Mean age was 66.5 years, and 64.7% were women. During a mean 6.5-year follow-up, crude incidence per 1000 patient years was driven by death. The incidence and all-cause death was highest for patients with high MPO (21.2; 95% CI, 19.0–23.7), then moderate (14.6; 95% CI, 11.5–18.5) and low (2.3; 95% CI, 1.2–4.6) MPO. After adjusting for age, sex, and cardiovascular risk factors, risk of cardiovascular death did not differ significantly between patients with high and low MPO (HR, 1.57; 95% CI, 0.56–4.39), but patients with high MPO had greater risk of non-cardiovascular (HR, 6.15; 95% CI, 2.27–16.64) and all-cause (HR, 3.83; 95% CI, 1.88–7.78) death. During follow-up, a 100 pmol/L decrease in MPO correlated with a 5% reduction in mortality (HR, 0.95; 95% CI, 0.93–0.97) over 5 years. CONCLUSIONS: Free circulating MPO is a strong marker of risk of mortality. Monitoring changes in MPO levels over time may provide insight into changes in physiology that mark a patient for increased risk of mortality.