Home oxygen therapy: an audit of survival

A retrospective audit of the medical records and respiratory function data of 186 subjects placed on long term continuous home oxygen therapy between 1979 and 1988 was undertaken. Kaplan-Meier survival curves were constructed for subjects with Chronic Obstructive Airways Disease (COAD) and Interstitial Lung Disease (ILD). There was an almost twofold greater mortality rate for COAD subjects at 12 months when compared to the Medical Research Council Working Party (MRC) and the Nocturnal Oxygen Therapy multicentre clinical trials (NOTT). However, the mean values of the baseline physiological parameters were similar to these major studies of long term oxygen therapy. Survival of ILD patients was significantly less than COAD patients (p less than 0.001). Within both disease categories, females survived significantly longer than males. Within the COAD category the observed sex difference was not abolished when the data was controlled for age, Pco2, Po2 and pack-years (as an estimate of total cigarette consumption). However, prior smoking history appeared to modify the male-female difference in COAD survival. These are the first Australian survivorship data for patients on long term oxygen therapy. The more adverse survival figures compared with the overseas studies may reflect the co-existence of other diseases.