Table 2

Comparison between the NNT to prevent a COPD exacerbation and the NNT to induce pneumonia properly computed from the corresponding cumulative incidences (CIs) for recent trials of the fluticasone-salmeterol combination inhaler (ICS) versus a long-acting bronchodilator

Time span for NNTCOPD exacerbationPneumonia
CI at end of studyCI at end of study
StudyICSNo ICSNNTICSNo ICSNNT
TORCH1 3 years0.922*0.945*440.1960.13316
INSPIRE4 2 years0.578†0.590†830.0940.04922
Kardos344 weeks0.470.55130.0450.01432
Ferguson5 1 year0.580.66130.070.0433
Anzueto6 1 year0.600.67140.070.0220
  • *CI not provided in paper; approximated by converting the incidence rate using the Poisson/exponential distribution. “No ICS” refers to the salmeterol group of the TORCH trial.

  • †CI not provided in paper; approximated by applying the rate ratio of exacerbations with fluticasone.17

  • COPD, chronic obstructive pulmonary disease; ICS, inhaled corticosteroid; NNT, number needed to treat.