Nail findings in patients with psoriatic arthritis: A cross-sectional study with special reference to transverse grooves

Background: Patients with psoriatic arthritis (PsA) commonly present with nail manifestations; however, little is known about these manifestations. Objective: This study investigated whether nail findings can be used to discriminate between PsA and psoriasis without arthritis. Methods: We performed a retrospective analysis of 118 patients with PsA and 974 patients with psoriasis without arthritis who visited St. Luke's International Hospital (Tokyo, Japan) between July 2003 and February 2015. Patients with PsA were classified according to the Classification of Psoriatic Arthritis criteria. Skin lesion severity was assessed by using the Psoriasis Area and Severity Index, and 9 types of nail findings were investigated. Results: The incidence of nail involvement in patients with PsA was 67.6%. Female sex, presence of transverse grooves, onycholysis, and splinter hemorrhages were significantly related to PsA, with transverse grooves demonstrating the strongest association (odds ratio, 5.01; 95% confidence interval, 2.31-10.8; P < .01). Furthermore, the presence of transverse grooves was strongly related to both distal interphalangeal arthritis and enthesitis. Limitations: The PsA population was relatively small. Conclusions: Nail findings enabled us to distinguish patients with PsA from those without arthritis. The presence of transverse grooves is significantly associated with PsA and may be associated with distal interphalangeal arthritis and enthesitis.