Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA.
Pharmacoepidemiol Drug Saf. 2011 Jul;20(7):700-8. doi: 10.1002/pds.2146. Epub 2011 May 14.
Ejection fraction (EF) is crucial information when studying the use and effectiveness of therapies in patients with heart failure (HF) and myocardial infarction (MI). We aimed to assess the validity of claims data-based definitions of systolic dysfunction (SD).
We identified 1072 patients with EF recorded for an HF/MI hospitalization in Medicare linked with pharmacy data and national HF/MI registries in 1999-2006. Thirteen claims-based definitions for SD were developed using a single or combination of ICD-9 diagnosis codes and cardiovascular medications use. We calculated sensitivity, specificity, and positive predictive values (PPVs) using recorded EFs as the gold standard.
Using an EF cutoff of 45%, the definitions based on digoxin use and no atrial fibrillation or flutter had the highest PPVs (76% to 84%) and specificity (>97%) but low sensitivity (6%-14%). As we varied the EF cutoff between 50% and 25%, the specificity decreased by 3%, but the PPVs decreased by 52%. We observed potential differences in the PPVs by patients' characteristics. In a hypothetical study assessing implantable defibrillator effectiveness, using our definition to identify patients with SD would underestimate the effectiveness by 3% to 24%. In another hypothetical study comparing two classes of angiotensin system blockers where SD was considered confounding, our definition introduced ~43% misclassification bias.
Claims-based definitions for SD had excellent specificity and good PPV but low sensitivity. The definitions with good PPV could be used for cohort identification or confounding adjustment by restriction and would result in relatively small misclassification bias albeit limited generalizability.
射血分数（EF）是研究心力衰竭（HF）和心肌梗死（MI）患者治疗方法的使用和疗效的关键信息。我们旨在评估基于索赔数据的收缩功能障碍（SD）定义的有效性。
我们在 1999-2006 年期间确定了 Medicare 与药房数据和国家 HF/MI 登记处相关联的 1072 例 EF 记录的 HF/MI 住院患者。使用单一或组合的 ICD-9 诊断代码和心血管药物使用，制定了 13 种基于索赔的 SD 定义。我们使用记录的 EF 作为金标准计算了敏感性、特异性和阳性预测值（PPV）。
使用 EF 截值为 45%，基于地高辛使用和无房颤或房扑的定义具有最高的 PPV（76%至 84%）和特异性（>97%），但敏感性较低（6%至 14%）。当我们在 50%和 25%之间变化 EF 截值时，特异性下降 3%，但 PPV 下降 52%。我们观察到患者特征对 PPV 的潜在差异。在一项评估植入式除颤器有效性的假设性研究中，使用我们的定义来识别 SD 患者将使有效性低估 3%至 24%。在另一项比较两类血管紧张素系统阻滞剂的假设性研究中，我们的定义引入了约 43%的混淆偏倚。
基于索赔数据的 SD 定义具有出色的特异性和良好的 PPV，但敏感性较低。具有良好 PPV 的定义可用于通过限制进行队列识别或混杂调整，并且尽管具有有限的通用性，但会导致相对较小的分类错误偏差。
