Table 2– Symptoms, quality of life, 6-min walking distance (6MWD) and arterial blood gases
Biomass groupTobacco groupp-value
Subjects n2122
Report of cough or sputum (from SGRQ)
 Subjects n2021
 Cough n (%)18 (90)16 (76)0.23
 Sputum n (%)18 (90)15 (71)0.13
Chronic Respiratory Questionnaire
 Control of disease (mastery)21±524±40.04+
Arterial blood gas
PaO2 mmHg49.3±7.752.5±40.11
PaCO2 mmHg36.9±5.433.1±40.01
SaO2 %82±887±40.01
SpO2 at rest %89±592±30.07
SpO2 at end of walk test %80±984±40.04
 Distance m306±118307±1520.98
  • Data are presented as mean±sd, unless otherwise stated. mMRC: modified Medical Research Council dyspnoea scale; SGRQ: St George’s Respiratory Questionnaire; PaO2: arterial oxygen tension; PaCO2: arterial carbon dioxide tension; SaO2: arterial oxygen saturation; SpO2: arterial oxygen saturation measured by pulse oximetry. #: higher values represent worse health status; : lower values represent worse health status; +: nonparametric test.