Background:
The neutrophil to lymphocyte ratio (NLR) has been proposed as a predictor of cardiovascular disease in some autoimmune diseases but not in psoriasis (PsO) or psoriatic arthritis (PsA)

Objective:
To assess the association of NLR with incident major adverse cardiovascular events (MACE) and all causesmortality in patients with PsO and PsA.
To evaluate the effect of treatment on NLR.

Methods:
Patients with PsO and PsA followed at a university hospital were included in this retrospective cohort study.
Patients contributed time from their diagnosis or first contact with the hospital until the development of MACE (composite of non-fatal myocardial infarction, non-fatal stroke, or CV death), or death, loss of follow-up, or finalization of the study (1/5/2022). NLR was calculated from the blood count at the time of diagnosis or first visit to the hospital before starting any systemic treatment. Patients with previous MACE were excluded.

Associations between baseline NLR (low:<2.5; high:>2,5) and incident MACE or death were analyzed using a Cox proportional hazards model adjusting for traditional cardiovascular risk factors and treatment.
Changes in percentages of patients with low and high cardiovascular risk (based on NLR) after biologic treatment were calculated.

Results:
967 patients followed for a total of 16239 patient/years (py) were included (table 1). There were 69 MACE (IR:0.43/100py); 64 in PsO (IR:0.44/100py) and 5 in PsA (IR:0.31/100py).

The incidence of MACE in patients with an NLR>2.5 was 0.63/100py compared with 0.35/100py in those with a NLR<2.5 (IRR:1.8; 95%CI:1.1-2.8; p=0.0106).

In the Cox proportional hazard model after adjusting for age, gender, diabetes, hypertension, body max index, dyslipidemia, smoking, and treatment, a NLR >2.5 was associated with an increased risk of MACE: hazard ratio (HR): 1.7 (95%CI:1.01-3; p=0.046). NLR>2.5 was associated with increased all-cause mortality in univariable analysis (IRR: 1.7; 95%CI:1.06-2.8), but not in multivariable analysis.

Between 6/12 months after the first biologic (data available in 83/93 patients) 17/25 (68%) with high baseline NLR reduced their NLR to a low-risk category (<2.5), while only 5/58 (8 %) with low NLR increased their risk (p=0.007). Only 2 MACES occurred in patients after biologics (IR: 0.09/100 py), and 9 in patients on MTX (IR:0.23/100 py)

Conclusion:
NLR is a universally available index, that was associated with an increased risk of MACE in patients with PsO and PsA.

There was a low incidence of MACE after initiation of biologics. After 6-12 months of biologic therapy, most patients reduced their NLR risk category.