title: Nailfold capillary density is importantly associated over time with muscle and skin disease activity in juvenile dermatomyositis.
abstract: OBJECTIVE
  To investigate the longitudinal association of nailfold capillary density (NCD; as a potential marker of activity) with various other clinical measures of disease activity and to evaluate baseline NCD as a predictor of disease outcome in children with JDM.
  
  
  METHODS
  Data from 809 clinic visits from 92 JDM patients were prospectively collected at each clinic visit over a time period of 5.5 years. The number of capillaries per millimetre at the distal nailfold was scored using a stereomicroscope. Disease activity was determined using the Childhood Myositis Assessment Scale (CMAS) and a modification of the validated disease activity score (DAS), which included three skin (SDAS) and three muscle (MDAS) criteria. An inception cohort subgroup (n=28) with a baseline visit at diagnosis was analysed separately.
  
  
  RESULTS
  Both DAS subscores, MDAS (β = -0.04437, P < 0.0001) and SDAS (β = -0.1589, P < 0.0001), as well as the CMAS (β = 0.02165, P < 0.0001) were significantly associated with loss of end row nailfold capillary over time (multiple regression mixed-model analysis). All patients in the inception subcohort showed a reduced baseline NCD (diagnostic sensitivity = 100%) that improved as the disease improved, but this did not predict longer term outcome or course of disease.
  
  
  CONCLUSIONS
  NCD is a marker of skin and muscle disease activity, and is an important measure of disease activity changes from visit to visit. Determination of capillary density may be useful when making treatment decisions. A decrease in NCD may be considered for inclusion in the diagnostic criteria due to its high sensitivity.
authors.affiliation: Department of Pediatrics, Division of Rheumatology, Alberta Children's Hospital, University of Calgary, 2888 Shaganappi Trail NW Calgary, AB T3B 6A8, Canada. heinrike.schmeling@albertahealthservices.ca
authors.forename: Heinrike
authors.initials: H
authors.lastname: Schmeling
authors.forename: Samantha
authors.initials: S
authors.lastname: Stephens
authors.forename: Cristina
authors.initials: C
authors.lastname: Goia
authors.forename: Cedric
authors.initials: C
authors.lastname: Manlhiot
authors.forename: Rayfel
authors.initials: R
authors.lastname: Schneider
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Luthra
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Stringer
authors.forename: Brian M
authors.initials: BM
authors.lastname: Feldman
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D002196:Capillaries / Q000473:pathology*; D002648:Child; D003882:Dermatomyositis / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009262:Nails / Q000098:blood supply*; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D011788:Quality of Life; D012044:Regression Analysis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012867:Skin / Q000503:physiopathology*
chemical_list: D000305:Adrenal Cortex Hormones; D008727:Methotrexate