Supplementary Material for: Estimation of the Prevalence of Amyotrophic Lateral Sclerosis in the United States Using National Administrative Healthcare Data from 2002 to 2004 and Capture-Recapture Methodology

Background: National administrative healthcare data may be used as a case-finding method for prevalence studies of chronic disease in the United States, but the completeness of ascertainment likely varies depending on the disease under study. Methods: We used 3 case-finding sources (Medicare, Medicaid, and Veterans Administration data) to estimate the prevalence of amyotrophic lateral sclerosis (ALS) in the United States for 2002–2004, and applied the capture-recapture methodology to estimate the degree of under-ascertainment when relying solely on these sources for case identification. Results: Case-finding completeness was 76% overall and did not vary by race, but was lower for males (77%) than for females (88%), and lower for patients under age 65 (66%) than patients over age 65 (79%). The uncorrected ALS prevalence ratio was 2.8/100,000 in 2002, 3.3/100,000 in 2003, and 3.7/100,000 in 2004. After correcting for under-ascertainment, the annual prevalence increased by approximately 1 per 100,000 to 3.7/100,000 in 2002 (95% CI 3.66–3.80), 4.4/100,000 in 2003 (95% CI 4.34–4.50), and 4.8/100,000 in 2004 (95% CI 4.76–4.91). Conclusions: Federal healthcare claims databases ascertained are a very efficient method for identifying the majority of ALS-prevalent cases in the National ALS Registry, and may be enhanced by having patients self-register through the registry web portal.

背景：美国国家级行政医疗数据可用于慢性疾病现患率研究的病例识别，但病例确认的完整性可能因研究疾病的不同而存在差异。
方法：本研究选取3类病例识别数据源——医疗保险（Medicare）、医疗补助计划（Medicaid）及美国退伍军人事务部医疗数据，对2002—2004年美国肌萎缩侧索硬化症（amyotrophic lateral sclerosis, ALS）的现患率进行估算；同时应用捕获-再捕获法，评估仅依靠上述数据源开展病例识别时的确认不足程度。
结果：总体病例识别完整性为76%，未呈现种族差异；但男性群体的完整性（77%）低于女性（88%），65岁以下患者（66%）低于65岁及以上患者（79%）。未校正的ALS现患率分别为2002年2.8/10万、2003年3.3/10万、2004年3.7/10万。经确认不足校正后，年现患率较此前提升约1/10万，2002年达3.7/10万（95%置信区间3.66~3.80），2003年达4.4/10万（95%置信区间4.34~4.50），2004年达4.8/10万（95%置信区间4.76~4.91）。
结论：用于病例确认的联邦医疗理赔数据库，是识别国家ALS登记库中绝大多数ALS现患病例的高效手段；可通过患者经由登记库门户网站自主登记的方式，进一步优化病例识别工作。