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Table 2 Rate ratios (RR) and 95% confidence intervals (CI) of amyotrophic lateral sclerosis (ALS) by smoking status before the onset of ALS, General Practice Research Database (GPRD), 1990-2008

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

 

ALS cases

Controls

RR (95% CI) *

RR (95% CI)**

Entire sample

Never

377 (33.0)

3714 (32.7)

1.00 (ref.)

1.00 (ref.)

Ever

575 (50.3)

5615 (49.4)

1.04 (0.80-1.34)

1.09 (0.81-1.46)

   Former

273 (23.9)

2696 (23.7)

1.01 (0.74-1.39)

1.15 (0.80-1.64)

   Current

302 (26.4)

2919 (25.7)

1.06 (0.79-1.41)

1.04 (0.74-1.47)

Missing

191 (16.7)

2042 (18.0)

0.88 (0.68-1.14)

0.94 (0.69-1.26)

Men

Never

207 (32.8)

1896 (30.3)

1.00 (ref.)

1.00 (ref.)

Ever

318 (50.4)

3180 (50.8)

0.75 (0.53-1.06)

0.75 (0.50-1.11)

   Former

157 (24.9)

1584 (25.3)

0.73 (0.48-1.11)

0.70 (0.43-1.14)

   Current

161 (25.5)

1596 (25.5)

0.76 (0.52-1.13)

0.79 (0.50-1.24)

Missing

106 (16.8)

1191 (19.0)

0.64 (0.44-0.92)

0.67 (0.44-1.02)

Women

Never

170 (33.2)

1818 (35.6)

1.00 (ref.)

1.00 (ref.)

Ever

257 (50.2)

2435 (47.7)

1.53 (1.04-2.23)

1.68 (1.08-2.61)

   Former

116 (22.7)

1112 (21.8)

1.49 (0.92-2.43)

2.06 (1.20-3.53)

   Current

141 (27.5)

1323 (25.9)

1.55 (1.01-2.38)

1.41 (0.84-2.36)

Missing

85 (16.6)

851 (16.7)

1.25 (0.85-1.82)

1.33 (0.86-2.04)

P interaction

  

0.01

0.02

  1. * Conditional logistic regression model adjusted for age, gender, practice, and time since enrolment in the GPRD.
  2. ** Results advancing five years index date (910 cases and 9058 controls). Conditional logistic regression model adjusted for age, gender, practice, and time since enrolment in the GPRD.