Price D, Ramachandran S, Knight T, Jones P W, Neary R H
Department of Clinical Biochemistry, North Staffordshire Hospital.
Br J Gen Pract. 2000 Sep;50(458):712-5.
Dietary advice is usually the first-line treatment for increased blood cholesterol in primary care with a reduction in levels as the expected response. In practice, the diet adopted by the patient may lead to changes in blood lipids characterised by a greater decrease in high-density lipoprotein (HDL) than total cholesterol. The ratio of total cholesterol to HDL cholesterol is an important factor in calculated coronary risk using the Framingham model, from which most risk tables currently in use have been derived. This suggests that either coronary risk may increase after dietary advice or that risk should always be assessed on measurements made before any intervention has taken place.
To report observed changes in blood lipids and calculated coronary risk following dietary advice in primary care.
Subjects with at least one coronary risk factor and baseline cholesterol above 5.2 mmol/l from an inner-city general practice had cardiovascular risk factors, including fasting lipids, recorded before receiving dietary advice. At follow-up several months later, risk factor measurements were repeated. Ten-year coronary risk was calculated using the Framingham model. Lipid levels and coronary risk at baseline and follow-up were compared.
There was a significant decrease in both total cholesterol and HDL cholesterol in both sexes. However, in 56% of subjects, HDL decreased by a greater proportion than the total cholesterol. These subjects showed a highly significant increase in the total cholesterol/HDL cholesterol ratio (median = 0.8 [semi-interquartile range = 1.5], P < 0.001, which was correlated with a change in triglycerides (rs = 0.309, P < 0.001). In those who had an increase in the total cholesterol/HDL cholesterol ratio, calculated coronary risk increased from 5.45% (13.2) at baseline to 7.25% (15.5) (P < 0.001). In all subjects, the change in calculated coronary risk associated with dietary advice ranged from -15% to 15%.
Low fat dietary advice in this primary care setting was frequently associated with undesirable changes in the lipid profile. The majority of subjects showed an increase in the total cholesterol/HDL cholesterol ratio, owing primarily to a decrease in HDL. Consequently, calculated coronary risk increased in over one-half of the subjects. Owing to our incomplete understanding of HDL metabolism, it is unclear whether the fall in HDL is actually detrimental; however, it seems prudent to give dietary advice to patients to avoid excess simple carbohydrate as a fat substitute. This helps avoid a rise in triglycerides, which appears to be associated with an increase in the ratio. These results confirm that coronary risk should always be calculated using measurements made before intervention.
在初级保健中，饮食建议通常是治疗血液胆固醇升高的一线疗法，预期反应是胆固醇水平降低。实际上，患者采用的饮食可能导致血脂变化，其特征是高密度脂蛋白（HDL）的降低幅度大于总胆固醇。总胆固醇与HDL胆固醇的比值是使用弗雷明汉模型计算冠心病风险的一个重要因素，目前使用的大多数风险表都源于该模型。这表明，饮食建议后冠心病风险可能增加，或者风险应该始终根据干预前的测量值进行评估。
报告初级保健中饮食建议后观察到的血脂变化及计算得出的冠心病风险。
来自市中心一家全科诊所的、至少有一个冠心病风险因素且基线胆固醇高于5.2 mmol/L的受试者，在接受饮食建议前记录了包括空腹血脂在内的心血管风险因素。几个月后的随访中，重复进行风险因素测量。使用弗雷明汉模型计算十年冠心病风险。比较基线和随访时的血脂水平及冠心病风险。
男女的总胆固醇和HDL胆固醇均显著降低。然而，56%的受试者中，HDL的降低比例大于总胆固醇。这些受试者的总胆固醇/HDL胆固醇比值显著升高（中位数 = 0.8 [半四分位间距 = 1.5]，P < 0.001），这与甘油三酯的变化相关（rs = 0.309，P < 0.001）。在总胆固醇/HDL胆固醇比值升高的受试者中，计算得出的冠心病风险从基线时的5.45%（13.2）增至7.25%（15.5）（P < 0.001）。在所有受试者中，与饮食建议相关的计算得出的冠心病风险变化范围为 -15%至15%。
在这种初级保健环境中，低脂饮食建议常常与不良的血脂变化相关。大多数受试者的总胆固醇/HDL胆固醇比值升高，主要原因是HDL降低。因此，超过一半的受试者计算得出的冠心病风险增加。由于我们对HDL代谢的理解不完整，尚不清楚HDL的下降是否真的有害；然而，向患者提供饮食建议以避免过多简单碳水化合物替代脂肪似乎是谨慎的做法。这有助于避免甘油三酯升高，而甘油三酯升高似乎与该比值增加有关。这些结果证实，冠心病风险应始终根据干预前的测量值进行计算。
