Ocaña-Riola Ricardo, Fernández-Ajuria Alberto, Mayoral-Cortés José María, Toro-Cárdenas Silvia, Sánchez-Cantalejo Carmen
Escuela Andaluza de Salud Pública, Granada, Spain.
Epidemiology. 2009 May;20(3):411-8. doi: 10.1097/EDE.0b013e318196aaf4.
Mortality is one of the most widely used indicators in small-area ecologic studies. Both accessibility to mortality data and advances in the development of new disease mapping techniques have contributed to an abundance of mortality maps and atlases over the last decade. Results may be biased in this kind of study if there has been unmeasured geographic mobility of the population. Most published papers tend to neglect this possibility. We use the theory of dynamics systems to demonstrate that migratory flows unmonitored by official population registers may lead to major errors in mortality rates and relative risks. Simulations in 4 scenarios showed more than 8% underestimation of the mortality rate and more than 11% underestimation of relative risk in areas with high uncontrolled emigration, and above 19% overestimation of mortality rate and above 15% overestimation of relative risk in areas with high uncontrolled immigration.Researchers conducting small-area epidemiologic studies should explore the reliability of population information in geographic areas before drawing hypothesis or conclusions on other possible causes of mortality differences.
死亡率是小区域生态研究中使用最广泛的指标之一。在过去十年中，死亡率数据的可获取性以及新疾病绘图技术的发展进步，都促使了大量死亡率地图和图集的出现。如果人口存在未被测量的地理流动性，那么这类研究的结果可能会有偏差。大多数已发表的论文往往忽略了这种可能性。我们运用动力系统理论来证明，官方人口登记未监测到的迁徙流动可能会导致死亡率和相对风险出现重大误差。在4种情景下的模拟显示，在不受控制的高移民地区，死亡率被低估超过8%，相对风险被低估超过11%；在不受控制的高迁入地区，死亡率被高估超过19%，相对风险被高估超过15%。开展小区域流行病学研究的人员在就死亡率差异的其他可能原因得出假设或结论之前，应探究地理区域内人口信息的可靠性。
