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Table 1 Characteristics of amyotrophic lateral sclerosis (ALS) cases and controls, General Practice Research Database, 1990-2008

From: Association of smoking with amyotrophic lateral sclerosis risk and survival in men and women: a prospective study

  ALS cases Controls
N 1143 11,371
Age at index date, years 67.4 (12.5) 67.1 (12.5)
   Range 23-95 20-97
Gender [% women] 44.8 44.9
Smoking [%]   
   Never 33.0 32.7
   Missing 16.7 18.0
   Ever 50.3 49.4
Former 23.9 23.7
Current 26.4 25.7
Non-heavy smokers 45.1 44.5
Heavy smokers 5.2 4.9
Body mass index, kg/m2 [%] *   
   <20 3.6 3.2
   20-24.9 33.1 30.1
   25-29.9 29.5 30.7
   ≥30 9.5 11.9
   Missing 24.3 24.2
Time between first smoking assessment and index date, years 14.1 (9.4) 14.0 (9.2)
Diagnosis [%]   
   ALS/MND 88.6  
   PBP 8.8  
   PMA 1.4  
   PLS 1.2  
Follow-up after diagnosis, years 2.1 (2.7)  
  1. Numbers refer to percentages or means (standard deviation).
  2. * Corresponding to first recording of body mass index in the GPRD (average 8.3 years before index date)
  3. ALS: amyotrophic lateral sclerosis; MND: motor neuron disease; PBP: progressive bulbar palsy; PLS: primary lateral sclerosis; PMA: progressive muscular atrophy