Observational Multicenter Case-control Study to Assess Nailfold Capillary Abnormalities in Systemic Lupus Erythematosus

Background and rationale:

Nailfold capillaroscopy (NC) is a diagnostic investigation used in the routine clinical setting for the differential diagnosis of connective tissue diseases, such as Systemic Lupus Erythematosus (SLE). Among SLE clinical manifestations, vascular involvement is a common feature and a variable prevalence of NC abnormalities has been reported in SLE: typical NC changes, as well as non-specific variations as observed in healthy subjects.

At this very moment literature is interspersed with different descriptions of capillaroscopic features in SLE, and it has not been clearly defined the role of NC in SLE patients. It has been suggested that the presence of major capillary abnormalities may reflect the microvascular systemic involvement in SLE, and it may correlate to the disease activity.

Against this background, the EULAR study group on microcirculation in rheumatic diseases planned an international multicenter study.

Objective:

To investigate the role of NC abnormalities in the assessment of SLE patients.

Endpoints:

Primary endpoint:

-To compare the frequency of major capillary abnormalities in patients with SLE and healthy controls.

Secondary endpoints:

• To compare the frequency of major capillary abnormalities in patients with active and non-active SLE / active SLE and healthy controls / non-active SLE and healthy controls.
• To study the association of different capillary parameters and the status of subjects (SLE / active SLE / non-active SLE / healthy controls).

No. of subjects:

Total entered: 364 ; Cases (SLE): 182 ; Controls: 182.

Variables

NC assessment: presence of major capillary abnormalities; NC parameters/mm: number of capillaries, presence of hairpin, tortuous, crossed, bushy, ramified, enlarged, giant capillaries, microhemorrhages, architecture disorganization, visibility of the subpapillary venular plexus; presence of scleroderma patterns, normal patterns.

Clinical assessment: all subjects: date of birth, gender, race. SLE: age at disease onset, disease activity (SLEDAI-2000) and damage index (SLICC-DI), presence of antinuclear antibodies, anti-dsDNA, anti-Extractable Nuclear Antigen antibodies, lupus anticoagulant, anticardiolipin/beta2glycoprotein I antibodies, Raynaud's phenomenon, Hypertension, active smoke, diabetes mellitus, ongoing and cumulative dose steroid treatment, ongoing immunomodulatory/suppressive treatment.

Statistical methods For the primary endpoint and similar secondary endpoints, McNemar test (matching design) and a conditional odds ratio (OR). For other secondary endpoints, the Fisher's exact test and an OR, and a conditional logistic regression model (matching design) and non-conditional regression model and OR as appropriate.

Inclusion criteria

• At time of enrollment all subjects must be 18 years or older and give written consent.
• Patients with SLE must fulfill the 2012 SLICC classification criteria.
• SLE onset must be over 16 years of age.
• Patients with SLE and secondary anti-phospholipid syndrome will be also enrolled.
• Healthy controls will be selected according to the definition proposed in the protocol

Exclusion criteria

• Subject refuses to sign and/or he/she is not able to understand the patient informed consent.
• Subjects with periungual traumatic lesions that may create artifacts (i.e. recent manicure, onychophagia, or gardening).
• SLE overlapping with other rheumatic diseases such as Systemic Sclerosis, Rheumatoid Arthritis, Mixed Connective Tissue Disease, Sjögren's Syndrome, Dermatomyositis, Polymyositis