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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