Association of Cycling With All-Cause and Cardiovascular Disease Mortality Among Persons With Diabetes—Reply

Abstract

To the Editor We read with great interest the Original Investigation recently published in this journal by Dr Ried-Larsen and colleagues. 1 The authors reported decreased mortality from all causes and from cardiovascular diseases associated with cycling in adults with diabetes. The large sample size and the robust analyses are strengths of the study. However, it is surprising that the reported association between cycling and mortality was independent of practicing other types of physical activity. An almost linear relationship between the amount of physical activity and mortality reduction (4% risk reduction per 15 min of additional physical activity per day) has been demonstrated for healthy individuals and for individuals living with cardiovascular disease. 2 While the findings by Ried-Larsen and colleagues may represent a unique feature of persons with diabetes, these findings may also be associated with a bias comparable to the "healthy worker effect." This phenomenon, known from occupational epidemiology studies, 3 was first discovered in 1885 by William Ogle, 4 who recognized that more physically demanding occupations attract healthier individuals. Reduced mortality rates in those workers may be partly attributable to a related selection bias. Cycling is among the more challenging modes of physical activity. Compared with other exercise types, such as (Nordic) walking, cycling may be especially demanding for older individuals, requiring high muscle strength, postural control, and self-perceived confidence. 5 Thus, whereas regular cycling would likely contribute to reduced all-cause mortality, the results of the study by Ried-Larsen and colleagues may be partly explained by healthier individuals being part of the cycling population. Moreover, the less healthy individuals may be less likely to start cycling during late adulthood; they may choose a safer activity.

Cycling for Health

“…The data in the report by Ried-Larsen and colleagues add to previous studies showing benefits of cycling compared with other physical activity. A previous large Danish study published in 2000 showed significant health benefits of cycling to work, such as a 40% decreased risk of mortality after multivariate adjustment, including leisure-time physical activity.…”

“…A previous large Danish study published in 2000 showed significant health benefits of cycling to work, such as a 40% decreased risk of mortality after multivariate adjustment, including leisure-time physical activity. The analysis from Ried-Larsen and colleagues strengthens the epidemiologic data on cycling and strongly suggests that it may contribute directly to longer and healthier lives. As avid and/or aspiring cyclists ourselves, we are sold on the mental and physical benefits of getting to work and seeing the world on 2 wheels, self-propelled, and think it is well worth a try.…”

“…In this issue of JAMA Internal Medicine , Ried-Larsen and colleagues report a longitudinal study of the benefits of cycling in a large cohort of persons with diabetes, with 110 944 person-years of follow-up, from 10 Western European countries. Cycling was associated with at least a 24% lower all-cause mortality when compared with noncyclists, independent of other physical activities and possible confounders.…”

The untapped health and climate potential of cycling in France: a national assessment from individual travel data

“…In terms of morbidity, we showed that the disease most frequently prevented were diabetes and cardio-vascular diseases. Previous studies reported that cycling also contributes to reducing mortality among adults with diabetes 35 , making it a relevant intervention for both primary and secondary prevention.…”

“…In terms of morbidity, we showed that the disease most frequently prevented were diabetes and cardio-vascular diseases. Previous studies reported that cycling also contributes to reducing mortality among adults with diabetes 41 , making it a relevant intervention for both primary and secondary prevention. Due to the lack of reliable medical costs data, our estimate disregarded some diseases which were considered in some previous HIA of cycling, especially depression 25,42 .…”