When predicting cardiovascular events, methods that use non-laboratory-based risk factors are as accurate as those that rely on laboratory-based values, according to an Article released on March 14, 2008 in The Lancet.

Approximately 80% of all cardiovascular deaths occur in developing countries. So, risk assessment of high risk patients in these areas, where laboratory testing could be inconvenient or unavailable, is often difficult. The use of non-laboratory-based risk factors are an important alternative that need to be explored.

To explore the efficacy of these techniques, Dr Thomas Gaziano, Division of Cardiovascular Medicine, Brigham & Women's Hospital, Boston, MA, USA, and colleagues re-analysed the subjects of the NHANES I study. This study, performed between 1971 and 1975, was a cohort study of 14,407 participants in the United States between 25 and 74 years old. This new study followed up on 6,186 of them who did not repot a history of cancer or cardiovascular disease, including symptoms such as heart attack, heart failure, stroke, and angina. A laboratory-based method, which required blood tests, examined the age, systolic blood pressure, smoking status, total cholesterol, reported diabetes status, and current treatment for high blood pressure. The non lab method checked the same factors but substituted body-mass index for the cholesterol.

Over a 21 year period, there were 1,529 first-time cardiovascular events, of which 578 (38%) were deaths due to cardiovascular disease. To assess the levels cardiovascular risk prediction accuracy, a c-statistic for each prediction method. In both men and women, the lab and non-lab methods gave very similar c-statistics. 

In developed countries, the added cost of cholesterol testing is about $10 per test and from $20 to $80 if a follow up visit is necessary. In developing countries, the cost of a test is $1 to $3, and the additional visit costs $3 to $7. To offer perspective, the authors point out that in India, which spends approximately $31 per person per year on health care, guidelines recommending cholesterol screening would require that more than 10% of the entire Indian health-care budget to be sunk into this single laboratory test. According to this study, a non-laboratory test could be just as effective, and could obtain the required risk factor informaiton in between 5 and 10 minutes. 

In conclusion, the authors suggest that adequate screening programs may not be out of reach in developing countries, despite sub-par conditions for laboratory testing. "Although this method requires further validation and calibration, use  of a simple non-laboratory approach, as suggested by WHO, could have profound effects on the affordability and availability of an adequate screening programme in developing countries. Initial screening without blood testing could lead to the quick initiation of treatment without the added cost or inconvenience of laboratory testing, and would also keep any potential loss to follow-up due to the extra step in testing to a minimum."

Dr Shanthi Mendis, WHO, Geneva, Switzerland, and Dr V Mohan, Madras Diabetes Research Foundation, India, contributed a Comment in the same issue, in which they caution that conclusions made in this population, which was entirely American, may not completely apply to populations in developing countries. "Although tools that use non-laboratory-based variables can help to improve affordability of screening programmes for non-communicable diseases, they should not compromise the safety of patients. For equitable care of cardiovascular disease and other major non-communicable diseases, universal access to a set of essential interventions, including laboratory assays, may be required, even in settings with limited resources."

Laboratory-based versus non-laboratory-based method for assessment of cardiovascular disease risk: the NHANES I Follow-up Study cohort
Dr Thomas A Gaziano MD, Cynthia R Young MSc, Garrett Fitzmaurice DSc, Sidney Atwood BA and J Michael Gaziano MD
The Lancet 2008; 371:923-931
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Non-laboratory-based prediction of cardiovascular risk
Shanthi Mendis, V Mohan
The Lancet - Vol. 371, Issue 9616, 15 March 2008, Pages 878-879
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Written by Anna Sophia McKenney