Low-income smokers (<USD 15 000 per year) | Higher-income smokers (>USD 15 000 per year) | p-value | |
Phase 1 | |||
Chronic bronchitis | 22 | 14 | <0.0001 |
mMRC score | 1.58±1.46 | 0.93±1.24 | <0.0001 |
mMRC score >2 | 49 | 28 | <0.0001 |
Severe exacerbation within the past year | 13 | 7 | <0.0001 |
SGRQ total | 31.74±23.3 | 19.3±18.8 | <0.0001 |
6MWD feet | 1297±381 | 1486±352 | <0.0001 |
SF-36 PCS | 42.0±11.2 | 47.1±10.0 | <0.0001 |
SF-36 MCS | 45.95±12.6 | 52.4±9.8 | <0.0001 |
Phase 2 | |||
Chronic bronchitis | 20 | 13 | <0.0001 |
mMRC | 1.64±1.51 | 0.99±1.29 | <0.0001 |
mMRC score >2 | 52 | 31 | <0.0001 |
Severe exacerbation within the past year | 14 | 7 | <0.0001 |
SGRQ total | 31.79±23.1 | 19.6±19.0 | <0.0001 |
6MWD feet | 1168±438 | 1356±420 | <0.0001 |
SF-36 PCS | 39.9±11.4 | 45.3±10.6 | <0.0001 |
SF-36 MCS | 48.0±11.7 | 53.6±9.5 | <0.0001 |
CAT score | 15.0±9.2 | 10.5±7.7 | <0.0001 |
Data are presented as % or mean±sd, unless otherwise stated. mMRC: modified Medical Research Council; SGRQ: St George's Respiratory Questionnaire; 6MWD: 6-min walking distance; SF-36: Medical Outcomes Study 36-item short-form questionnaire; PCS: physical component summary; MCS: mental component summary; CAT: Chronic Obstructive Pulmonary Disease Assesment Test.