Table 2

Effect of ICS on FEV1 categorised by smoking status

PeriodStudySmoking statusChange in FEV1*Estimated effect of ICS on FEV1 outcomes*P valueEstimated effect of smoking on FEV1 outcomes in ICS users*P value
ICSPlacebo
Smoking: pack-year history
0–6 monthsPauwelsSubjects with ≤36 pack-year history†30−90120<0.001−50
Subjects with >36 pack-year history†0−70700.57
9–36 monthsPauwelsSubjects with ≤36 pack-year history†−47−71240.0822
Subjects with >36 pack-year history†−67−65-20.65
0–30 monthsSnoeck-StrobandSubjects with ≥42 pack years†−28−63350.242−750.023
Subjects with <42 pack years†18−921100.037
Smoking: smoking status
0–6 monthsZhengNever-smoked (n=52)2611411200.3592
Ex-smokers (n=297)17761710.006851
Current smokers (n=96)112−851970.00220.337662338
0–12 monthsBhattSmokers (n=7678)220.038
Ex-smokers (n=8807)300.0058
  • *Change in FEV1 reported. Values are in mL, except for Pauwels (1999) and Snoeck-Stroband (2015) data are expressed as mL/year.

  • †Number of participants in each study group not reported.

  • ‡P value cannot be calculated from data.

  • FEV1, forced expiratory volume in 1 s; ICS, inhaled corticosteroids.