Cytosolic 5'-nucleotidase 1A autoantibody profile and clinical characteristics in inclusion body myositis.
OBJECTIVES
Autoantibodies directed against cytosolic 5'-nucleotidase 1A have been identified in many patients with inclusion body myositis. This retrospective study investigated the association between anticytosolic 5'-nucleotidase 1A antibody status and clinical, serological and histopathological features to explore the utility of this antibody to identify inclusion body myositis subgroups and to predict prognosis.


MATERIALS AND METHODS
Data from various European inclusion body myositis registries were pooled. Anticytosolic 5'-nucleotidase 1A status was determined by an established ELISA technique. Cases were stratified according to antibody status and comparisons made. Survival and mobility aid requirement analyses were performed using Kaplan-Meier curves and Cox proportional hazards regression.


RESULTS
Data from 311 patients were available for analysis; 102 (33%) had anticytosolic 5'-nucleotidase 1A antibodies. Antibody-positive patients had a higher adjusted mortality risk (HR 1.89, 95% CI 1.11 to 3.21, p=0.019), lower frequency of proximal upper limb weakness at disease onset (8% vs 23%, adjusted OR 0.29, 95% CI 0.12 to 0.68, p=0.005) and an increased prevalence of excess of cytochrome oxidase deficient fibres on muscle biopsy analysis (87% vs 72%, adjusted OR 2.80, 95% CI 1.17 to 6.66, p=0.020), compared with antibody-negative patients.


INTERPRETATION
Differences were observed in clinical and histopathological features between anticytosolic 5'-nucleotidase 1A antibody positive and negative patients with inclusion body myositis, and antibody-positive patients had a higher adjusted mortality risk. Stratification of inclusion body myositis by anticytosolic 5'-nucleotidase 1A antibody status may be useful, potentially highlighting a distinct inclusion body myositis subtype with a more severe phenotype.
['Lilleker|J B|JB|http://orcid.org/0000-0002-9230-4137', 'Rietveld|A|A|', 'Pye|S R|SR|', 'Mariampillai|K|K|', 'Benveniste|O|O|', 'Peeters|M T J|MT|', 'Miller|J A L|JA|', 'Hanna|M G|MG|', 'Machado|P M|PM|', 'Parton|M J|MJ|', 'Gheorghe|K R|KR|', 'Badrising|U A|UA|', 'Lundberg|I E|IE|', 'Sacconi|S|S|', 'Herbert|M K|MK|', 'McHugh|N J|NJ|', 'Lecky|B R F|BR|', 'Brierley|C|C|', 'Hilton-Jones|D|D|', 'Lamb|J A|JA|', 'Roberts|M E|ME|', 'Cooper|R G|RG|', 'Saris|C G J|CG|', 'Pruijn|G J M|GJ|', 'Chinoy|H|H|', 'van Engelen|B G M|BG|', '|||']
D015720:5'-Nucleotidase D017668:Age of Onset D000368:Aged D000369:Aged, 80 and over D001323:Autoantibodies D015415:Biomarkers D003600:Cytosol D003576:Electron Transport Complex IV D005260:Female D006801:Humans D053208:Kaplan-Meier Estimate D008297:Male D008875:Middle Aged D018485:Muscle Fibers, Skeletal D018908:Muscle Weakness D018979:Myositis, Inclusion Body D011379:Prognosis D016016:Proportional Hazards Models D012189:Retrospective Studies D012656:Self-Help Devices D015996:Survival Rate D013997:Time Factors
Autoantibodies Dermatomyositis Polymyositis