title: Cardiovascular fitness as a risk factor for amyotrophic lateral sclerosis: indirect evidence from record linkage study.
abstract: BACKGROUND
  Amyotrophic lateral sclerosis (ALS) appears to be a sporadic disorder in 95% of cases. Although few personal characteristics associated with developing ALS are known, identification of those at risk is essential to any vision of early intervention. There is persistent anecdotal observation that those with ALS are premorbidly physically 'fitter', although such observations are susceptible to bias. Hospital admission for coronary heart disease (CHD) might serve as an objective marker of reduced cardiovascular fitness.
  
  
  METHODS
  A record linkage study of two large databases of hospital admissions, the Oxford Record Linkage Study (ORLS) and an English national record linkage dataset of Hospital Episode Statistics was undertaken. The ratio of the rate of ALS in people without a record of CHD to that in those with a record of CHD was calculated, factoring out premature death in both cohorts. Similar analysis for Parkinson's disease (PD) and multiple sclerosis (MS) was undertaken.
  
  
  RESULTS
  In the English population, the rate ratio for ALS in the non-CHD cohort, compared with the CHD cohort, was 1.14 (95% CI 1.05 to 1.22); for PD it was 0.95 (95% CI 0.93 to 0.98); and for MS 0.95 (95% CI 0.88 to 1.04). The ORLS data yielded similar findings.
  
  
  CONCLUSIONS
  Those without a record of CHD were at modestly higher risk of ALS, but not for PD or MS. This lends support to the assertion that ALS arises within a population who may have relatively higher levels of cardiovascular fitness.
authors.affiliation: Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK. martin.turner@clneuro.ox.ac.uk
authors.forename: Martin R
authors.initials: MR
authors.lastname: Turner
authors.forename: Clare
authors.initials: C
authors.lastname: Wotton
authors.forename: Kevin
authors.initials: K
authors.lastname: Talbot
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Goldacre
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology*; D002320:Cardiovascular Physiological Phenomena; D015984:Causality; D015331:Cohort Studies; D015897:Comorbidity; D003327:Coronary Disease / Q000453:epidemiology; D003625:Data Collection; D004198:Disease Susceptibility; D061345:Early Medical Intervention; D006801:Humans; D015994:Incidence; D061213:Mortality, Premature; D009103:Multiple Sclerosis / Q000453:epidemiology; D010300:Parkinson Disease / Q000453:epidemiology; D010809:Physical Fitness; D012307:Risk Factors; D016019:Survival Analysis