Your racing horses will help you to quit: a lesson for COPD and alpha1-antitrypsin deficiency research.

T he more we learn about spirometry, the more we could be challenged. Au contraire, farmers are proficient about horses and are experienced in identifying young thoroughbreds with potential talent. They refer to the horseracing effect by saying that, if you train a fine, young stallion, you might well end up with a winner; and that horses who are leading a race, at a point closer to the finish line, are more likely to win it than those leading at earlier parts of the track. Mathematically, this effect is referred to as co-linearity; your baseline position determines your likely future position. In respiratory medicine, we know about the horse-racing effect from the famous pulmonary curves of FLETCHER and PETO [1], a model postulated 40 yrs ago but not yet validated. It could be assumed that by serially testing with spirometry those at a high risk of chronic obstructive pulmonary disease (COPD), such as heavy smokers, you could identify an increased slope of forced expiratory volume in one second (FEV1) decline. This increased decline could be used as a screening tool for those who finally develop the disease. In 1981, this was named as the lung function horse-racing effect [2]. As stated by FLETCHER and PETO [1], ‘‘In a race between fast and slow horses ... one would expect to find the faster horses out in front halfway through the race’’.