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Table 4 Mean annual change in FEV1 per pack-year to 1991 and per pack of cigarettes smoked per day between 1991 and 2002 in quitters* and persistent smokers

From: Accelerated decline in lung function in smoking women with airway obstruction: SAPALDIA 2 cohort study

  Term Annual change in mL per pack-year to 1991 Annual change in mL per packs per day between 1991 and 2002
   Coef 95%CI p value Coef 95%CI p value
Quitters†        
Men (n = 245) Linear -0.1 -0.4, 0.3 0.78 -14.3 -22.6, -6.0 0.001
   Women (n = 179) Linear 1.5 0.3, 2.6 0.01 -6.4 -17.6, 4.6 0.25
  Quadratic -0.04 -0.08,-0.01 0.01 na na na
  Cubic 0.0004 0.0001,0.0006 0.006 na na na
Persistent smokers†        
Men (n = 595) Linear -0.1 -0.3, 0.12 0.41 -9.0 -15.4, -2.5 0.006
   Women (n = 556) Linear 1.4 0.5, 2.3 0.001 -11.6 -19.8, -3.5 0.005
  Quadratic -0.06 -0.08, -0.02 <0.001 na na na
  Cubic 0.0006 0.0003, 0.0008 <0.001 na na na
  1. *Quitters were current smokers in 1991 who had stopped smoking by 2002.
  2. † P values for interaction between persistent smoking and quitting with packs per day: men = 0.49 women = 0.05
  3. na: no association with polynomial terms
  4. Effects estimated from regression models with same covariates as in Table 3