Table 3

Posthoc analysis of sample size calculations for secondary outcome measures

Outcome analysisTreatment effect*Required sample size
FEV1% predicted–1.8±12.0351
FEV1 (litres)–0.06±0.290
FEF25–75% predicted–5.3±22.3141
FEF25–75 (litres)–0.1±0.6285
CFQ-R respiratory domain–5.2±14.261
CFQ-R parent respiratory domain–5.9±16.262
  • * Treatment effect between isotonic saline and hypertonic saline treatment periods.

  • Required number of patients for a crossover trial to achieve 80% power at a 5% significance level.

  • CFQ-R, Cystic Fibrosis Questionnaire-Revised; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; FEF25–75, forced expiratory flow at 25–75% of the forced vital capacity.