Review question
Are systematic risk assessment (screening) programmes helpful in the prevention of cardiovascular disease?
Background
Cardiovascular disease (CVD) is a group of conditions affecting the heart and blood vessels. CVD is a global burden and is still the number one cause of early death and disability worldwide. Identification of those at increased risk of cardiovascular disease through screening-like programmes may help with CVD prevention and management.This review assessed the effectiveness of systematic risk assessment or a screening-like programme in reducing cardiovascular death, death from any cause, non-fatal events (such as heart attacks, strokes and angina) and CVD risk factors in healthy adults and adults at high risk of CVD.
Study characteristics
We searched scientific databases for randomised controlled trials (clinical trials where people are allocated at random to one of two or more treatments), looking at the effects of systematic risk assessment in healthy adults or those at high risk of developing CVD. We did not include people who already had CVD (e.g. heart attacks and strokes), as these are already known to health services and are being treated. The evidence is current to January 2015.
Key results
Nine trials met our inclusion criteria. Limited data suggest that screening has no effect on deaths (from any cause) or the number of people having a stroke or developing coronary heart disease. Data were also limited for cardiovascular risk factors (blood lipids and blood pressure) where there were some favourable effects with systematic risk assessment, but there were differences between studies and so results are not certain.
Quality of the evidence
The evidence was generally of low or very low quality. Included studies were at some risk of bias, with four studies judged at high risk of bias. Bearing this in mind, the results of this review need to be interpreted cautiously.
There is currently limited evidence on the effects of systematic risk assessment for the prevention of CVD. We identified five ongoing trials and when the results are available we will incorporate these.
The results are limited by the heterogeneity between trials in terms of participants recruited, interventions and duration of follow-up. Limited data suggest that systematic risk assessment for CVD has no statistically significant effects on clinical endpoints. There is limited evidence to suggest that CVD systematic risk assessment may have some favourable effects on cardiovascular risk factors. The completion of the five ongoing trials will add to the evidence base.
Screening programmes can potentially identify people at high cardiovascular risk and reduce cardiovascular disease (CVD) morbidity and mortality. However, there is currently not enough evidence showing clear clinical or economic benefits of systematic screening-like programmes over the widely practised opportunistic risk assessment of CVD in primary care settings.
The primary objective of this review was to assess the effectiveness, costs and adverse effects of systematic risk assessment compared to opportunistic risk assessment for the primary prevention of CVD.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on the Cochrane Library, MEDLINE, EMBASE on 30 January 2015, and Web of Science Core Collection and additional databases on the Cochrane Library on 4 December 2014. We also searched two clinical trial registers and checked reference lists of relevant articles. We applied no language restrictions.
We selected randomised controlled trials (RCTs) that assessed the effects of systematic risk assessment, defined as a screening-like programme involving a predetermined selection process of people, compared with opportunistic risk assessment which ranged from no risk assessment at all to incentivised case finding of CVD and related risk factors. Participants included healthy adults from the general population, including those who are at risk of CVD.
Two review authors independently selected studies. One review author extracted data and assessed them for risk of bias and a second checked them. We assessed evidence quality using the GRADE approach and present this in a ’Summary of findings’ table.
Nine completed RCTs met the inclusion criteria, of which four were cluster-randomised. We also identified five ongoing trials. The included studies had a high or unclear risk of bias, and the GRADE ratings of overall quality were low or very low. The length of follow-up varied from one year in four studies, three years in one study, five or six years in two studies, and ten years in two studies. Eight studies recruited participants from the general population, although there were differences in the age ranges targeted. One study recruited family members of cardiac patients (high risk assessment). There were considerable differences between the studies in the interventions received by the intervention and control groups. There was insufficient evidence to stratify by the types of risk assessment approaches.
Limited data were available on all-cause mortality (risk ratio (RR) 0.98, 95% confidence interval (CI) 0.93 to 1.03; 3 studies,103,571 participants, I² = 0%; low-quality evidence) and cardiovascular mortality (RR 1.00, 95% CI 0.90 to 1.11; 2 studies, 43,955 participants, I² = 0%), and suggest that screening has no effect on these outcomes. Data were also limited for combined non-fatal endpoints; overall, evidence indicates no difference in total coronary heart disease (RR 1.01, 95% CI 0.95 to 1.07; 4 studies, 5 comparisons, 110,168 participants, I² = 0%; low-quality evidence), non-fatal coronary heart disease (RR 0.98, 95% CI 0.89 to 1.09; 2 studies, 43,955 participants, I² = 39%), total stroke (RR 0.99, 95% CI 0.90 to 1.10; 2 studies, 79,631 participants, I² = 0%, low-quality evidence), and non-fatal stroke (RR 1.17, 95% CI 0.94 to 1.47; 1 study, 20,015 participants).
Overall, systematic risk assessment appears to result in lower total cholesterol levels (mean difference (MD) -0.11 mmol/l, 95% CI -0.17 to -0.04, 6 studies, 7 comparisons, 12,591 participants, I² = 57%; very low-quality evidence), lower systolic blood pressure (MD -3.05 mmHg, 95% CI -4.84 to -1.25, 6 studies, 7 comparisons, 12,591 participants, I² = 82%; very low-quality evidence) and lower diastolic blood pressure (MD -1.34 mmHg, 95% CI -1.76 to -0.93, 6 studies, 7 comparisons, 12,591 participants, I² = 0%; low-quality evidence). One study assessed adverse effects and found no difference in psychological distress at five years (1126 participants).