Rosvall Maria, Engström Gunnar, Berglund Göran, Hedblad Bo
Social Epidemiology, Department of Clinical Sciences in Malmö, Lund University, Malmö University Hospital, Malmö, Sweden.
BMC Public Health. 2008 Jun 2;8:189. doi: 10.1186/1471-2458-8-189.
The widespread use of relative scales in socioepidemiological studies has recently been criticized. The criticism is based mainly on the fact that the importance of different risk factors in explaining social inequalities in cardiovascular disease (CVD) varies, depending on which scale is used to measure social inequalities. The present study examines the importance of established risk factors, as opposed to low-grade inflammation, in explaining socioeconomic differences in the incidence of CVD, using both relative and absolute scales.
We obtained information on socioeconomic position (SEP), established risk factors (smoking, hypertension, and hyperlipidemia), and low-grade inflammation as measured by high-sensitive (hs) C-reactive protein (CRP) levels, in 4,268 Swedish men and women who participated in the Malmö Diet and Cancer Study (MDCS). Data on first cardiovascular events, i.e., stroke or coronary event (CE), was collected from regional and national registers. Social inequalities were measured in relative terms, i.e., as ratios between incidence rates in groups with lower and higher SEP, and also in absolute terms, i.e., as the absolute difference in incidence rates in groups with lower and higher SEP.
Those with low SEP had a higher risk of future CVD. Adjustment for risk factors resulted in a rather small reduction in the relative socioeconomic gradient, namely 8% for CRP (>/= 3 mg/L) and 21% for established risk factors taken together. However, there was a reduction of 18% in the absolute socioeconomic gradient when looking at subjects with CRP-levels < 3 mg/L, and of 69% when looking at a low-risk population with no smoking, hypertension, or hyperlipidemia.
C-reactive protein and established risk factors all contribute to socioeconomic differences in CVD. However, conclusions on the importance of "modern" risk factors (here, CRP), as opposed to established risk factors, in the association between SEP and CVD depend on the scale on which social inequalities are measured. The one-sided use of the relative scale, without including a background of absolute levels of disease, and of what causes disease, can consequently prevent efforts to reduce established risk factors by giving priority to research and preventive programs looking in new directions.
社会流行病学研究中相对量表的广泛使用近来受到了批评。这种批评主要基于这样一个事实，即不同风险因素在解释心血管疾病（CVD）社会不平等方面的重要性各不相同，这取决于用于衡量社会不平等的量表。本研究使用相对量表和绝对量表，考察既定风险因素而非低度炎症在解释CVD发病率社会经济差异方面的重要性。
我们获取了4268名参与马尔默饮食与癌症研究（MDCS）的瑞典男性和女性的社会经济地位（SEP）、既定风险因素（吸烟、高血压和高脂血症）以及通过高敏（hs）C反应蛋白（CRP）水平测量的低度炎症信息。首次心血管事件的数据，即中风或冠状动脉事件（CE），从地区和国家登记处收集。社会不平等用相对术语衡量，即低SEP组和高SEP组发病率之间的比率，也用绝对术语衡量，即低SEP组和高SEP组发病率的绝对差异。
低SEP者未来患CVD的风险更高。对风险因素进行调整后，相对社会经济梯度的降低幅度相当小，即CRP（≥3mg/L）为8%，既定风险因素综合起来为21%。然而，当观察CRP水平<3mg/L的受试者时，绝对社会经济梯度降低了18%，当观察无吸烟、高血压或高脂血症的低风险人群时，降低了69%。
C反应蛋白和既定风险因素都导致了CVD的社会经济差异。然而，关于“现代”风险因素（此处为CRP）相对于既定风险因素在SEP与CVD关联中的重要性的结论，取决于衡量社会不平等的量表。因此，单方面使用相对量表，而不考虑疾病的绝对水平背景以及病因，可能会通过优先开展新方向的研究和预防项目，阻碍为降低既定风险因素所做的努力。
