ABSTRACT
Increasing age is an independent risk factor for mortality and morbidity following medical interventions. However, chronological age alone is not the consistent, quantifi able risk factor that it may at fi rst sight seem to be. Although subjectively we might agree that the older a patient is, the more at risk they are of complications or consequences of the effects of a medical procedure, it is not always possible to express this as a reliable odds ratio of harm. For example, everyone will be familiar with the 60-year-old person who ‘looks older than their years’ and who has limited activity compared with other people of the same age and, in contrast, the sprightly 90-year-old who still goes hill running. The athletic 90-year-old could be regarded as ‘younger’ than his nonagenarian counterparts, and the 60-year-old as ‘older’ than his cohort. This perception is often expressed in terms of physiological age as opposed to chronological age. This concept is useful when considering the risks of being elderly, in that it relates health to function and activity. However, at present the concept can only be used with regard to quantifying an individual’s activity as better, the same as or worse than that which would normally be expected for someone of similar age. Investigators are currently evaluating more scientifi c ways of assessing this concept using objective tests such as the determination of anaerobic exercise tolerance levels. Current research in this area is extremely promising, as it appears that a low anaerobic threshold (AT) – that is, the activity level at which anaerobic metabolism starts – is associated with a quantifi ably higher risk of mortality from major surgery. However, the technique is still in its infancy, and has not been applied to patients undergoing minor procedures.1
