Abstract
Background
When two or more cardiovascular risk factors occur in one individual, they may interact in a multiplicative way promoting cardiovascular disease. Exercise has proven to be effective in controlling individual risk factors but its effect on overall cardiovascular risk remains uncertain.
Objectives
To assess the effects of exercise training in people with increased cardiovascular risk but without a concurrent cardiovascular disease on general cardiovascular mortality, incidence of cardiovascular events, and total cardiovascular risk.
Search methods
A search was conducted in CENTRAL (The Cochrane Library 2013, Issue 10 of 12), Ovid MEDLINE (1946 to week 2 November 2013), EMBASE Classic + EMBASE via Ovid (1947 to Week 47 2013), CINAHL Plus with Full Text via EBSCO (to November 2013), Science Citation Index Expanded (SCI-EXPANDED) (1970 to 22 November 2013), and Conference Proceedings Citation Index – Science (CPCI-S) (1990 to 22 November 2013) on Web of Science (Thomson Reuters). We did not apply any date or language restrictions.
Selection criteria
Randomized clinical trials comparing aerobic or resistance exercise training versus no exercise or any standard approach that does not include exercise. Participants had to be 18 years of age or older with an average 10-year Framingham risk score of 10% for cardiovascular disease over 10 years, or with two or more cardiovascular risk factors, and no history of cardiovascular disease.
Data collection and analysis
The selection of studies and subsequent data collection process were conducted by two independent authors. Disagreements were solved by consensus. The results were reported descriptively. It was not possible to conduct a meta-analysis because of the high heterogeneity and high risk of bias in the included studies.
Main results
A total of four studies were included that involved 823 participants, 412 in the exercise group and 411 in the control group. Follow-up of participants ranged from 16 weeks to 6 months. Overall, the included studies had a high risk of selection, detection, and attrition bias. Meta-analysis was not possible because the interventions (setting, type and intensity of exercise) and outcome measurements were not comparable, and the risk of bias in the identified studies was high. No study assessed cardiovascular or all-cause mortality or cardiovascular events as individual outcomes. One or more of the studies reported on total cardiovascular risk, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, blood pressure, body mass index, exercise capacity, and health-related quality of life but the available evidence was not sufficient to determine the effectiveness of exercise. Adverse events and smoking cessation were not assessed in the included studies.
Authors’ conclusions
Evidence to date is entirely limited to small studies with regard to sample size, short-term follow-up, and high risk of methodological bias, which makes it difficult to derive any conclusions on the efficacy or safety of aerobic or resistance exercise on groups with increased cardiovascular risk or in individuals with two or more coexisting risk factors. Further randomized clinical trials assessing controlled exercise programmes on total cardiovascular risk in individuals are warranted.
Plain language summary
Exercise for people with increased cardiovascular risk
Individuals with more than one cardiovascular risk factor, such as hypertension, high cholesterol, or smoking, are more likely to present with cardiovascular disease. While exercise has been proven to be effective in controlling individual risk factors, the evidence for its effect on multiple risks remains uncertain. We included four studies, with 823 participants in total, comparing exercise for increased-risk individuals against control or no treatment. Follow-up of patients ranged from 16 weeks to six months. No study assessed cardiovascular or all-cause mortality, or cardiovascular events as individual outcomes. One or more of the studies reported on total cardiovascular risk, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol, blood pressure, body mass index, exercise capacity, and health-related quality of life, but the results did not provide conclusive evidence of the effects of exercise in this population. The included studies did not assess smoking cessation or any adverse effects of the exercise intervention. We conclude that the evidence to date is entirely limited to small studies in terms of sample size, short-term follow-up, and high-risk of methodological bias, which makes it difficult to derive any conclusions on the efficacy or safety of the exercise carried out in the included trials on total cardiovascular risk, mortality, or cardiovascular events. It is necessary to conduct high-quality clinical trials that evaluate the effect of exercise on people with increased cardiovascular risk.
