Validity of a Self-administered Questionnaire Version of the Transition Dyspnea Index in Patients with COPD

Figures & data

Table 1. Mean (SD) baseline characteristics of participants.

Characteristics	Data
Age (yr)	58 (8)
Sex (female/male), No.	61/129
FEV1 (L)	1.59 (0.57)
FEV1 (% predicted)	51 (15)
VC (L)	3.31 (0.91)
VC (% predicted)	83 (15)
FEV1/VC (%)	48 (11)
Dyspnea (mMRC)	2.60 (1.15)
BMI (kg^*m^−2)	27.3 (6.6)
Exacerbations in preceding 12 months, No.	2.3 (1.1)
6 MWD (m)	436 (110)
Chronic oxygen use, No.	18
Smoking status, No.
Current smoker	73
Former smoker	108
Never smoker	9
COPD severity based on airflow limitation according to GOLD (No.)
II	88
III	73
IV	29
COPD severity based on combined assessment according to GOLD (No.)
A	6
B	53
C	4
D	127

6 MWD = 6-minute walk distance; BMI = body mass index; FEV₁ = forced expiratory volume in first second; VC = vital capacity; mMRC = modified Medical Research Council Scale.

Table 2. Means (SD) and correlations of questionnaire TDI and interview TDI.

	Questionnaire TDI	Interview TDI	Correlations^‡	Correlations Mahler et al. (30,31)
Functional impairment^#	1.2 (1.3)	1.4 (1.1)	0.74^*** (0.84)	0.72^***
Magnitude of task	1.8 (1.1)	1.8 (1.1)	0.96^*** (0.98)	0.80^***
Magnitude of effort	1.3 (1.2)	1.3 (1.1)	0.98^*** (0.99)	0.78^***
TDI summary score^§	4.3 (3.2)	4.5 (3.0)	0.94^*** (0.97)	0.94^***

^#p < 0.05 and

^§p < 0.01 for the comparison between questionnaire TDI and interview TDI.

^***p < 0.001.

^‡intraclass correlation coefficients are presented in parentheses.

Note: The right column presents comparable correlations between an interviewer-administered and a self-administered computerized version of the TDI as obtained by Mahler et al. (30,31).

Figure 1. Summary scores for questionnaire TDI and interview TDI.

Figure 2. Bland–Altman plot showing the difference between the questionnaire TDI and interview TDI summary scores against the mean of the questionnaire TDI and interview TDI summary scores. Overall, the majority of patients showed no difference in dyspnea estimates between the questionnaire and interview TDI version. The range of summary scores for the TDI is −9 (deterioration) to +9 (improvement). Solid line: mean value; dashed line: mean ± 1.96 SD of the scores.

Table 3. Correlations of TDI summary scores and changes in lung function and dyspnea from start to end of pulmonary rehabilitation.

	Questionnaire TDI	Interview TDI
▵FEV1 (% predicted)	0.17^*	0.21^**
▵VC (% predicted)	0.17^*	0.20^**
▵Dyspnea (mMRC)	−0.22^**	−0.24^**

^*p < 0.05,

^**p < 0.01

FEV₁ = forced expiratory volume in first second; VC = vital capacity; mMRC = modified Medical Research Council Scale.