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Table 3 Outcome means by average ΔFEV1 category, P values for associations between average ΔFEV1 and outcome, and correlations at individual and cohort levels

From: Correlating changes in lung function with patient outcomes in chronic obstructive pulmonary disease: a pooled analysis

Average ΔFEV1 (ml) Category midpoint value of ΔFEV1 (ml) Withdrawal rate* (% patients) TDI at 12 weeks (n = 2781) TDI at 24/26 weeks (n = 2208) TDI at 52 weeks (n = 1099) ΔSGRQ at 12 weeks (n = 3141) ΔSGRQ at 24/26 weeks (n = 2215) ΔSGRQ at 52 weeks (n = 1115) Rescue medication mean puffs per day (over study duration) (n = 3158) Exacerbation rate (per year) (n = 3158) Severe exacerbation rate (per year) (n = 3158)
-500, -50 -275 11.2 1.44 1.57 1.24 -3.15 -4.70 -2.21 2.46 0.63 0.059
-50, 50 0 9.0 1.31 1.39 1.92 -3.17 -3.81 -3.03 2.57 0.58 0.065
50, 150 100 10.1 1.79 1.97 1.65 -3.84 -4.74 -4.22 2.10 0.61 0.057
150, 250 200 10.2 2.12 2.23 2.23 -5.84 -6.34 -6.70 1.80 0.51 0.048
250, 500 375 6.7 2.68 3.03 3.27 -7.38 -7.29 -9.06 1.66 0.38 0.021
P value (Kruskal-Wallis)    < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 0.1
Correlation, individual level    0.15 0.14 0.18 -0.12 -0.07 -0.16 -0.11 -0.06 -0.03
Correlation, cohort level    0.90 0.88 0.92 -0.90 -0.79 -0.95 -0.88 -0.89 -0.81
  1. *Non-completers in all studies categorised by ΔFEV1 at Day 2; ΔFEV1, change from baseline in trough forced expiratory volume in 1 second; TDI, Transition Dyspnoea Index; ΔSGRQ, change from baseline in St George's Respiratory Questionnaire