Westfall J M, McGloin J
University of Colorado Health Sciences Center, and the High Plains Research Network, Denver, Colorado, USA.
Med Care. 2001 May;39(5):459-68. doi: 10.1097/00005650-200105000-00006.
Ischemic heart disease is the leading cause of death in the United States. Recent studies report inconsistent findings on the changes in the incidence of hospitalizations for ischemic heart disease. These reports have relied primarily on hospital discharge data. Preliminary data suggest that a significant percentage of patients suffering acute myocardial infarction (MI) in rural communities are transferred to urban centers for care. Patients transferred to a second hospital may be counted twice for one episode of ischemic heart disease.
To describe the impact of double counting and transfer bias on the estimation of incidence rates and outcomes of ischemic heart disease, specifically acute MI, in the United States.
Analysis of state hospital discharge data from Kansas, Colorado (State Inpatient Database [SID]), Nebraska, Arizona, New Jersey, Michigan, Pennsylvania, and Illinois (SID) for the years 1995 to 1997. A matching algorithm was developed for hospital discharges to determine patients counted twice for one episode of ischemic heart disease. Validation of our matching algorithm.
Patients reported to have suffered ischemic heart disease (ICD9 codes 410-414, 786.5).
Number of patients counted twice for one episode of acute MI.
It is estimated that double count rates range from 10% to 15% for all states and increased over the 3 years. Moderate sized rural counties had the highest estimated double count rates at 15% to 20% with a few counties having estimated double count rates a high as 35% to 50%. Older patients and females were less likely to be double counted (P <0.05).
Double counting patients has resulted in a significant overestimation in the incidence rate for hospitalization for acute MI. Correction of this double counting reveals a significantly lower incidence rate and a higher in-hospital mortality rate for acute MI. Transferred patients differ significantly from nontransferred patients, introducing significant bias into MI outcome studies. Double counting and transfer bias should be considered when conducting and interpreting research on ischemic heart disease, particularly in rural regions.
缺血性心脏病是美国的主要死因。最近的研究报告了关于缺血性心脏病住院发病率变化的不一致结果。这些报告主要依赖于医院出院数据。初步数据表明，农村社区中患有急性心肌梗死（MI）的患者中有很大一部分被转至城市中心接受治疗。因缺血性心脏病发作而转至第二家医院的患者可能会被重复计算。
描述重复计数和转诊偏倚对美国缺血性心脏病（特别是急性MI）发病率和结局估计的影响。
分析1995年至1997年堪萨斯州、科罗拉多州（州住院患者数据库[SID]）、内布拉斯加州、亚利桑那州、新泽西州、密歇根州、宾夕法尼亚州和伊利诺伊州（SID）的州医院出院数据。开发了一种用于医院出院数据的匹配算法，以确定因缺血性心脏病发作而被重复计算的患者。对我们的匹配算法进行验证。
报告患有缺血性心脏病（国际疾病分类第九版代码410 - 414、786.5）的患者。
因急性MI发作而被重复计算的患者数量。
据估计，所有州的重复计数率在10%至15%之间，且在这3年中有所增加。中等规模的农村县的估计重复计数率最高，为15%至20%，少数县的估计重复计数率高达35%至50%。老年患者和女性被重复计数的可能性较小（P<０.０５）。
对患者的重复计数导致急性MI住院发病率的显著高估。纠正这种重复计数后，急性MI的发病率显著降低，住院死亡率升高。转诊患者与未转诊患者有显著差异，给MI结局研究带来了显著偏倚。在开展和解释缺血性心脏病研究时，尤其是在农村地区，应考虑重复计数和转诊偏倚。
