The tyranny of the averages and the indiscriminate use of risk factors in public health: The case of coronary heart disease. (December 2017)

• Record Type: Journal Article
• Authors: Merlo, Juan; Mulinari, Shai; Wemrell, Maria; Subramanian, SV; Hedblad, Bo
• Is Part Of: SSM - population health. Volume 3(2017)
• Page Start: 684
• Page End: 698
• Publication Date: 2017-12
• Subjects: AUC Area under the ROC curve -- ACE Average causal effect -- CABG Coronary artery bypass graft -- CHD Coronary heart disease -- CRP C-reactive protein -- DA Discriminatory accuracy -- FPF False positive fraction -- HR Hazard ratios -- HDL High-density lipoprotein cholesterol -- ICE Individual causal effect -- Lp-PLA2 Lipoprotein-associated phospholipase A2 -- LDL Low-density lipoprotein cholesterol -- NTBNP N-terminal pro–brain natriuretic peptide -- OR Odds ratio -- PCI Percutaneous coronary intervention -- PAH Phenylalanine hydroxylase -- PKU Phenylketonuria -- PAF Population attributable fraction -- RCT Randomized clinical trial -- ROC Receiver operating characteristic -- RR Relative risk -- MDC study The Malmö Diet and Cancer -- TPF True positive fraction; Risk factors -- Coronary heart disease -- Discriminatory accuracy -- Population attributable fraction -- Over-diagnosis -- Overtreatment -- Individual heterogeneity -- Multilevel analysis; Social medicine -- Periodicals; Medical anthropology -- Periodicals; Public health -- Periodicals; Psychology -- Periodicals; Medicine -- Periodicals; 362.105
• DOI: 10.1016/j.ssmph.2017.08.005
• Languages: English
• ISSNs: 2352-8273

Abstract

Abstract: Modern medicine is overwhelmed by a plethora of both established risk factors and novel biomarkers for diseases. The majority of this information is expressed by probabilistic measures of association such as the odds ratio (OR) obtained by calculating differences in average "risk" between exposed and unexposed groups. However, recent research demonstrates that even ORs of considerable magnitude are insufficient for assessing the ability of risk factors or biomarkers to distinguish the individuals who will develop the disease from those who will not. In regards to coronary heart disease (CHD), we already know that novel biomarkers add very little to the discriminatory accuracy (DA) of traditional risk factors. However, the value added by traditional risk factors alongside simple demographic variables such as age and sex has been the subject of less discussion. Moreover, in public health, we use the OR to calculate the population attributable fraction (PAF), although this measure fails to consider the DA of the risk factor it represents. Therefore, focusing on CHD and applying measures of DA, we re-examine the role of individual demographic characteristics, risk factors, novel biomarkers and PAFs in public health and epidemiology. In so doing, we also raise a more general criticism of the traditional risk factors' epidemiology. We investigated a cohort of 6103 men and women who participated in the baseline (1991–1996) of the Malmö Diet and Cancer study and were followed for 18 years. We found that neither traditional risk factors nor biomarkers substantially improved the DA obtained by models considering only age and sex. We concluded that the PAF measure provided insufficient information for the planning of preventive strategies in the population. We need a better understanding of the individual heterogeneity around the averages and, thereby, a fundamental change in the way we interpret risk factors in public health and epidemiology. Highlights: There is a plethora of differences in "average" risk between exposed and unexposed groups of individuals. Individual heterogeneity around average values is seldom considered in Public Health. Measures of discriminatory accuracy (DA) informs on the underlying individual heterogeneity. Most know risk factors and other categorizations associated with diseases have low DA. We need a fundamental change in the way we investigate risk factors and other categorizations in Public Health.