Prevalence of hypoxaemic chronic obstructive lung disease with reference to long-term oxygen therapy.

Of the Sheffield population aged 45 years or more, an estimated 0.3% (confidence interval 0.06%-0.5%) had intra-arterial oxygen pressures less than or equal to 7.3 kPa and forced expiratory volumes less than 50% of predicted values (ie, had hypoxaemic chronic obstructive lung disease). According to both the USA Medicare criteria for reimbursement and the UK Department of Health and Social Security draft guidelines for prescribing long-term oxygen, 603 (confidence interval 134-1072) subjects in Sheffield would be eligible to have oxygen supplied by concentrator, and 60 000 (confidence interval 13 000-107 000) in England and Wales. This is considerably higher than the number now prescribed long-term oxygen by general practitioners. In less than a quarter of the cases was there hypercapnia (PaCO2 greater than or equal to 6.1 kPa). The majority of those most severely affected were current smokers, and one-quarter were receiving no medication. General practitioners are unlikely to be able to assess accurately a patient's need for long-term oxygen treatment without specialised advice and measurement.