Quality of life in patients with chronic obstructive pulmonary disease and severe hypoxaemia

Patients with severe chronic obstructive pulmonary disease (COPD) have impairment in most areas of quality of life, but a relationship between impairment of the partial pressure of oxygen in arterial blood (PaO2) and quality of life has not been established. Previous studies used general health measures such as the Sickness Impact Profile (SIP). In this study a disease-specific health measure, the St George's Respiratory Questionnaire (SGRQ), was used to examine the relationship.

Forty one patients (20 men) of median age 71 years (range 47-85) with COPD were assessed. Forced expiratory volume in one second (FEV1), PaO2 and partial pressure of carbon dioxide in the arterial blood (PaCO2) were measured, and the patients completed the SGRQ, SIP, and the Hospital Anxiety and Depression Scale (HAD).

The mean (SD) values were: FEV1, 0.83 (0.29) litres; PaO2, 7.49 (1.03) kPa; PaCO2, 6.30 (1.05) kPa; SGRQ total score, 55.3 (18.2); SIP total score 15.4 (9.2); anxiety score, 5.7 (4.3); depression score, 5.3 (3.4). PaO2 was significantly correlated with the SGRQ total scores but not with the SIP total score. The SGRQ total score also correlated with anxiety and depression. Multivariate analysis showed that depression score and PaO2 were both significant covariates of the SGRQ total score.

These findings suggest that, in patients with severe COPD, quality of life is related to the severity of hypoxaemia, but this relationship is only detectable when using a disease-specific health measure.