title: A 15-year prospective longitudinal study of disease progression in patients with HTLV-1 associated myelopathy in the UK.
abstract: BACKGROUND
  The natural history of HTLV-1-associated myelopathy (HAM) has been mainly described in HTLV-1 endemic countries such as Japan, Brazil and Martinique.
  
  
  OBJECTIVE
  The authors describe the natural history of the largest cohort of patients with HAM living in the UK from 1993 to 2007.
  
  
  METHODS
  Prospective, longitudinal study comparing clinical and virological outcome between first and last clinical visit. Incidence and cause of death were documented and the mortality calculated.
  
  
  RESULTS
  48 patients were included: 79.2% were female, 79.2% were of Afro-Caribbean origin, and 83.3% acquired HTLV-1 through breastfeeding or unprotected heterosexual intercourse. The mean age of onset was 46 years. The median durations from onset of symptoms to diagnosis and to last follow-up were 2 and 11.6 years. The median time of follow-up was 3.8 years. The most common first recalled symptom was unilateral leg weakness. The median times from onset to unilateral, bilateral walking aid and frame or a wheelchair were 11, 11.2, 11.3 and 18 years. The overall average deterioration in timed walk in patients whose need for aid did not change was 2 s/10 m/year. Three patients progressed rapidly and were unable to walk within 2 years. Six patients were slow/non-progressors. The mortality was 2.4/100 person year follow-up. The median HTLV-1 viral load remained unchanged at 14%.
  
  
  CONCLUSIONS
  HAM is a slowly progressing chronic disease. Timed walk deteriorates by 2 s/10 m/year, and patients remain ambulant for 10 years but become wheelchair-dependent a decade later. HTLV-1 viral load remains high and unchanged over time regardless of clinical progression.
authors.affiliation: National Centre for Human Retrovirology, Imperial College Healthcare NHS Trust, St Mary's Hospital, London, UK. f.martin@imperial.ac.uk
authors.forename: Fabiola
authors.initials: F
authors.lastname: Martin
authors.forename: Alexandra
authors.initials: A
authors.lastname: Fedina
authors.forename: Silva
authors.initials: S
authors.lastname: Youshya
authors.forename: Graham P
authors.initials: GP
authors.lastname: Taylor
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D002648:Child; D015331:Cohort Studies; D004185:Disability Evaluation; D018450:Disease Progression; D005260:Female; D015490:HTLV-I Infections / Q000175:diagnosis* / Q000401:mortality / Q000635:transmission; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009460:Neurologic Examination; D010147:Pain Measurement; D015493:Paraparesis, Tropical Spastic / Q000175:diagnosis* / Q000401:mortality / Q000635:transmission; D011446:Prospective Studies; D016019:Survival Analysis; D006113:United Kingdom; D055815:Young Adult