Association of normal nailfold end row loop numbers with a shorter duration of untreated disease in children with juvenile dermatomyositis

Abstract

To determine the association of normal numbers of end row loops (ERLs) in nailfold capillaries at the time of diagnosis of juvenile dermatomyositis (DM) with clinical findings in untreated children with the disease and to identify predictors of the development of decreased numbers of ERLs. Clinical and laboratory data from 80 untreated children with juvenile DM were collected. ERL numbers were recorded at the time of diagnosis and at 24 months and 36 months thereafter. The 12 children who had normal ERLs at diagnosis were compared with the remaining 68 children. Outcomes included the duration of untreated disease, the duration of treatment with immunosuppressive medications, family medical history, Disease Activity Score (DAS) for juvenile DM, creatinine phosphokinase level, aldolase level, absolute number of CD3-CD56+/16+ natural killer cells, and von Willebrand factor antigen level. Cross-sectional and longitudinal analyses were performed. At diagnosis, children with normal ERLs had a shorter duration of untreated disease (P = 0.03) and a lower skin DAS (P = 0.045). Over time, an increased likelihood of having decreased numbers of ERLs was associated with a longer duration of untreated disease and with a higher skin DAS. The presence of a normal number of ERLs in juvenile DM appears to be associated with a shorter duration of symptoms and may be a useful indicator of disease chronicity in the newly diagnosed child. Normal ERLs is also associated with a lower skin DAS. The lack of association between normal ERLs and other variables indicates that normal findings on nailfold capillaroscopy should not be used as justification to delay immunosuppressive therapy in children with typical symptoms of juvenile DM.