What defines healthy and happy old age, and especially being elderly without suffering from cardiovascular disease or risking cardiovascular events?(1) Several pieces of evidence support the importance of maintaining an active lifestyle, controlling risk factors (e.g. by avoiding cigarette smoking or other product of tobacco or nicotine-containing products), and preventing cardiovascular disease.(2) Patients are often given these recommendations, and they are commonly reinforced, but still many people cannot follow them duly.
Harb and colleagues, from the leading Cleveland Clinic, provide a compelling and 126,356-patient strong rationale for adopting and maintaining a healthy lifestyle, offering also physicians a uniquely useful tool to inform and motivate patients: age estimated from exercise testing (Figure 1).(3) In their carefully conducted and reported work, including patients undergoing exercise testing at their institution between 1991 and 2015, they highlight how prognosis was significantly predicted by chronological age, gender, history of coronary artery disease, diabetes mellitus, hypertension, statin use, end-stage renal disease, smoking, body mass index, peak exercise capacity, abnormal heart rate recovery, and chronotropic reserve index (all p<0.05). While this exercise in prognostic research is not novel in itself, and may miss important pieces of prognostic information,(4-6) it is still a useful reminder.
Most importantly though, Harb et al walk the extra mile and introduce an intriguing novel concept: age estimated by exercise testing (at odds from chronological age). Basically, exploiting readily available data from any exercise test (i.e. peak exercise capacity, abnormal heart rate recovery, and chronotropic reserve index), we can provide invidual patients an estimate of their age based on their stress-testing exercise performance (A-BEST). For instance, a 65-year-old lady with an A-BEST of 55 years will have a much better prognosis than a 50-year-old gentleman with an A-BEST of 60 years. Most importantly, A-BEST will be useful for supporting changes in a patient's lifestyle, and reinforce compliance (eg to diet and medication recommendations).
Despite the favorable implications of this work and similar ones, individual risk prediction remains challenging, and areas under the curve ranging around 0.80 still mean that 20% of patients will be inaccurately classfied. Accordingly, we should mantain a positive and constructive approach to patient risk-stratification and cardiovascular prevention, without falling into the trap of spurious precision. A beneficial adjunct could indeed be the addition of 95% confidence or credible intervals to individual point estimates of A-BEST.
In conclusion, while being young-young (i.e. young for chronological age as well as A-BEST) remains the best option, with the passing of time we should all aim to be and remain old-young (i.e. old for chronological age but young for A-BEST).
Figure 1. Secrets for healthy aging and improving age based on their stress testing exercise performance (A-BEST).