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1032 The Niemann-Pick Type C Suspicion Index Tool: Examination of its Discriminatory Power by Age and Associations by Leading Symptoms
  1. CJ Hendriksz1,
  2. M Pineda2,
  3. FA Wijburg3,
  4. F Sedel4,
  5. M Fahey5,
  6. M Walterfang6,
  7. MC Patterson7,
  8. H Chadha-Boreham8,
  9. SA Kolb8,
  10. JE Wraith9
  1. 1Department of Adult Inherited Metabolic Disease, Salford Royal Hospital NHS Foundation Trust, Manchester, UK
  2. 2Department of Pediatric Neurology, Hospital Sant Joan de Déu, Barcelona, Spain
  3. 3Department of Paediatrics, University of Amsterdam, Amsterdam, The Netherlands
  4. 4Federation of Nervous System Diseases, Groupe Hospitalier Pitié-Salpêtrière, Paris, France
  5. 5Department of Paediatrics, Monash University
  6. 6Department of Neuropsychiatry, University of Melbourne, Melbourne, VIC, Australia
  7. 7Division of Child and Adolescent Neurology, Mayo Clinic, Rochester, MN, USA
  8. 8Actelion Pharmaceuticals Ltd., Allschwil, Switzerland
  9. 9Willink Biochemical Genetics Unit, Royal Manchester Children’s Hospital, Manchester, UK

Abstract

Background and Aims The Suspicion Index (SI) screening tool was developed to identify suspected patients with Niemann-Pick disease type C (NP-C, Neurology, 2012). The SI provides Risk Prediction Score (RPS) based on NP-C symptoms within and across domains (visceral, neurological, and psychiatric). To further examine a) discriminatory power of the SI by age and b) symptom-associations by NP-C suspicion-level and leading symptoms.

Methods The original retrospective data were split into three age groups, where NP-C positive cases were: >16 years (n=30), 4–16 years (n=18), and < 4 years (n=23), and patients’ RPS was analysed by logistic regression. Co-occurrence of symptoms within groups of suspicion-level (low, medium, and high) and leading symptoms (presence/absence of ataxia, cognitive decline, psychosis, and splenomegaly) were analysed descriptively.

Results NP-C positive cases vs. controls showed strong discriminatory power of RPS. Area under the Receiver Operating Characteristic curve was 0.964 (>16 years) and 0.981 (4–16 years) but a weaker 0.562 for infants (< 4 years). Patients with RPS < 70 were characterised by a lack of psychiatric symptoms and low levels of neurological involvement, suggestive of a more visceral phenotype. In patients >4 years, prominent leading symptoms’ associations were: ataxia with “dystonia, dysarthria/dysphagia and cognitive decline”; psychosis with “dysarthria/dysphagia”; and psychotic symptoms with “cognitive decline and treatment-resistant psychiatric symptoms”.

Conclusions The SI tool maintains strong discriminatory power in patients >4 years but is not as useful for infants < 4 years. The SI is informative regarding the association and co-occurrence of symptoms in patients with NP-C.

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