Porta Miquel, Ferrer-Armengou Olga, Pumarega José, López Tomàs, Crous-Bou Marta, Alguacil Juan, Fitó Montserrat, Jariod Manuel, Vicente Angel, Morales Eva, Covas María-Isabel, Puigdomènech Elisa, Gupta Nikhil
Institut Municipal d'Investigació Mèdica-Hospital del Mar, Barcelona, Spain.
J Clin Epidemiol. 2008 Jul;61(7):695-704. doi: 10.1016/j.jclinepi.2007.08.013. Epub 2008 Mar 10.
Disease-induced changes in blood concentrations of lipids may bias etiologic studies. We analyzed the influence of clinical factors and timing of blood extraction on serum concentrations of cholesterol and triglycerides in exocrine pancreatic cancer (EPC).
Subjects were 144 incident cases of EPC prospectively recruited in five teaching hospitals in eastern Spain.
Higher concentrations of cholesterol, triglycerides, and total lipids were observed among patients with a shorter interval from first symptom of cancer to blood extraction (IES); but concentrations were lower in patients with longer IES. The relationship between cholesterol and tumor stage was "n-shaped." Jaundice and other components of the cholestatic syndrome increased cholesterol and triglycerides. Invasive diagnostic tests were associated with lower cholesterol. All these factors were related to changes >50mg/dl in cholesterol (P<0.05), even when adjusting by stage. Statistical models including IES, number of invasive diagnostic tests, jaundice, weight loss, and stage explained over 28% of the variation in lipid concentrations.
Restriction and adjustment by stage may be insufficient to prevent biases related to disease progression. Multivariate analyses may allow to control to some extent the influence of clinical symptoms, procedures, and timing of blood extraction in studies on the etiological significance of lipids and lipophilic compounds, either risk factors or protective agents.
疾病引起的血脂浓度变化可能会使病因学研究产生偏差。我们分析了临床因素和采血时间对外分泌性胰腺癌（EPC）患者血清胆固醇和甘油三酯浓度的影响。
研究对象为西班牙东部五家教学医院前瞻性招募的144例新发EPC病例。
从癌症首发症状到采血的间隔时间（IES）较短的患者中，胆固醇、甘油三酯和总脂质的浓度较高；而IES较长的患者中这些浓度较低。胆固醇与肿瘤分期之间的关系呈“n”形。黄疸和胆汁淤积综合征的其他成分会使胆固醇和甘油三酯升高。侵入性诊断检查与较低的胆固醇水平相关。即使按分期进行调整，所有这些因素与胆固醇变化>50mg/dl均相关（P<0.05）。包括IES、侵入性诊断检查次数、黄疸、体重减轻和分期在内的统计模型解释了脂质浓度变化的28%以上。
按分期进行限制和调整可能不足以防止与疾病进展相关的偏差。多变量分析可能在一定程度上有助于控制临床症状、检查程序和采血时间对脂质和亲脂性化合物病因学意义（无论是危险因素还是保护剂）研究的影响。
