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Table 2 Factors associated with a minimum clinically important difference in 6 min walk test according to a distribution-based definition. Distribution-based approach following Cohen’s moderate effect size, 41 m in this study cohort

From: Lung function and collagen 1a levels are associated with changes in 6 min walk test distance during treatment of TB among HIV-infected adults: a prospective cohort study

 

Minimum clinical important difference (N = 43)

No minimum difference (N = 46)

Scale factor

Unadjusted odds ratio of MCID

Baseline

Baseline

(N = 43)

(N = 46)

  

Demographics

Age (year, mean ± standard deviation)

37.3 (± 7.6)

37.1 (± 8.6)

 

1.00 (0.95, 1.06)

Male sex (n, %)

24 (56%)

28 (61%)

 

0.81 (0.35, 1.89)

Ever smoke (n, %)

19 (44%)

13 (28%)

 

2.58 (1.04, 6.63)

Clinical characteristics (mean ± standard deviation)

Six-minute walk distance (meters)a

357 (± 60)

427 (± 59)

10 m

0.83 (0.76, 0.90)

Sputum culture positivity* (count (%))

16 (37%)

23 (50%)

 

0.59 (0.25, 1.37)

Time between anti-tuberculosis treatment and antiretroviral therapy (days)

33 (± 20)

26 (± 16)

 

1.02 (1.00, 1.05)

Body mass index (kg/m2)

19.3 (± 2.4)

20.4 (± 4.1)

 

0.90 (0.76, 1.03)

CD4 count (cells/mm3)

127 (± 135)

165 (± 130)

10 cells/mm3

0.98 (0.94, 1.01)

Plasma HIV RNA level (log10 (copies/mm3))

5.4 (± 1.0)

5.2 (± 1.1)

 

1.14 (0.75, 1.77)

Forced vital capacity (FVC, liters)

3.0 (± 0.8)

3.2 (± 0.9)

100 mL

0.97 (0.92, 1.02)

FVC predicted (%)a

81.2 (± 19.6)

85.7 (± 18.3)

5%

0.94 (0.83, 1.06)

Forced expiratory volume in 1 s (FEV1, liters)

2.2 (± 0.7)

2.5 (± 0.7)

100 mL

0.94 (0.87, 1.00)

FEV1 predicted (%)

72.7 (± 19.5)

80.5 (± 18.7)

5%

0.90 (0.79, 1.01)

COPD** Assessment test total score

8.0 (± 6.7)

6.6 (± 6.0)

 

1.04 (0.97, 1.11)

Biomarkers (mean ± standard deviation)

Collagen Ia (pg/L)a

2080 (± 1170)

2930 (± 2230)

1000 pg/L

0.72 (0.49, 0.96)

TIMP1 (pg/L)a

208,000 (± 110,000)

152,000 (± 95,500)

10000 pg/L

1.05 (1.01, 1.10)

CCL2 (pg/L)

224 (± 109)

236 (± 105)

100 pg/L

0.89 (0.59, 1.34)

CXCL11 (pg/L)

109 (± 88.1)

94.1 (± 86.0)

10 pg/L

1.02 (0.97, 1.07)

IL8 (pg/L)

13.0 (± 6.94)

13.0 (± 7.85)

1 pg/L

1.00 (0.94, 1.06)

MMP1 (pg/L)

990 (± 595)

1090 (± 972)

100 pg/L

0.98 (0.93, 1.04)

VCAM1 (pg/L)

2,450,000 (± 1,550,000)

2,040,000 (± 1,030,000)

1000000 pg/L

1.28 (0.92, 1.85)

CXCL10 (pg/L)

506 (± 339)

561 (± 828)

100 pg/L

0.99 (0.91, 1.06)

IL6 (pg/L)

6.3 (± 9.4)

8.3 (± 12.3)

10 pg/L

0.83 (0.49, 1.25)

M-CSF (pg/L)a

213 (± 130)

162 (± 124)

10 pg/L

1.03 (1.00, 1.07)

Plasminogen activator (pg/L)

955 (± 335)

907 (± 304)

100 pg/L

1.05 (0.92, 1.21)

VEGF (pg/L)

17.1 (± 9.9)

16.9 (± 9.2)

1 pg/L

1.00 (0.96, 1.05)

  1. Missing—11% in ever smoke, BMI, CD4, viral load, FVC, FVC pred, FEV1, and FEV1pred; 4% in time to ART; and 5% in biomarkers
  2. *Study recruitment at baseline was within 30 days from anti-TB treatment initiation, and hence the culture results may already be conversed to negative
  3. **COPD, Chronic Obstructive Pulmonary Disease
  4. aStatistically significant difference in mean values at baseline at alpha = 0.05
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BMC Pulmonary Medicine

ISSN: 1471-2466

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