In the United States (US), spirometers use either correction factors of 10% to 15% for individuals labelled ‘black’ and 4% to 6% for people labelled ‘Asian’, or population-specific standards, usually those derived from the third US-based National Health and Nutrition Examination Survey for ‘Caucasians’, African Americans and Hispanics ( 5). Alternatively, they recommend correction factors ( 4). The Joint Working Party of the American Thoracic Society/European Respiratory Society recommends the use of race- and ethnic-specific references values when available. Because ‘correction’ is programmed into the spirometer by the manufacturer, it can be difficult to disable.ĭespite attempts by international organizations, the approach to ‘correction’ or ‘adjustment’ is not always consistent. Interviews with users of the spirometer indicate that many operators are unaware that they are automatically activating race correction when they select a patient’s race ( 3). How race (or population) is determined varies, with most operators either asking patients to self-identify or ‘eyeballing it’. To enable the spirometer, the operator must select the race of an individual, as well as indicate their age, sex/gender and height. Most commercially available spirometers internationally ‘correct’ or ‘adjust’ for race in one of two ways: by using a scaling factor for all people not considered to be ‘white’ or by applying population-specific norms.

One outcome of global standardization projects is the common practice of ‘race correction’, also called ‘ethnic adjustment’. Since the 1960s, much effort has been expended to standardize the many sources of variability. Temporal trends can be quite dramatic, with lung function increasing in certain populations and decreasing in others during the same time period ( 2). The great variability in lung function measurements over time, space, within countries, within individuals, among groups and among spirometers, however, has complicated the interpretation of ‘normal’. Chronic obstructive respiratory disease, a major cause of disability and mortality, is defined by spirometry ( 1). Over the past century, the spirometer has gained widespread use across the world for the diagnosis and management of many respiratory diseases in both specialist and primary care settings.

Race