迄今为止，缺铁性贫血（IDA）和/或便血成人的诊断测试完成率和诊断内窥镜或结肠镜检查的时间尚未得到很好的表征。年龄小于 50 岁、患有 IDA 和/或便血的退伍军人。这项队列研究是退伍军人健康管理局于 1999 年 10 月 1 日至 2019 年 12 月 31 日期间进行的，研究对象为来自 2 个不同队列的 18 至 49 岁美国退伍军人：诊断为 IDA 的患者 (n = 59169) 和诊断为便血的患者 (n = 189185)。统计分析于2021年8月至2023年8月进行。诊断测试因素包括年龄、性别、种族和民族、退伍军人健康管理局地理区域和血红蛋白测试值（仅限IDA队列）。诊断测试的主要结果是（1）双向内窥镜检查诊断 IDA 后和 (2) 诊断便血后进行结肠镜检查或乙状结肠镜检查。使用泊松模型检查诊断测试因素与诊断测试完成之间的关联。 有 59169 名退伍军人被诊断为 IDA（平均 [SD] 年龄，40.7 [7.1] 岁；30502 名男性 [51.6%]），189185 名诊断为便血的退伍军人（平均 [SD] 年龄，39.4 [7.6] 岁；163690 名男性 [86.5%]），以及 2287 名患有 IDA 和便血的退伍军人（平均 [SD] 年龄，41.6 [6.9] 岁；1856 名男性[81.2%]）。患有 IDA 的退伍军人的累计 2 年诊断检查完成率为 22%（95% CI，22%-22%），患有便血的退伍军人为 40%（95% CI，40%-40%）。患有 IDA 的退伍军人大多年龄在 40 至 49 岁之间（37719 人 [63.7%]），其中黑人比例过高（24480 人 [41.4%]）。与患有 IDA 的男性相比，患有 IDA 的女性（比率 [RR]，0.42；95% CI，0.40-0.43）完成诊断测试的可能性较低。与患有 IDA 的白人退伍军人相比，患有 IDA 的黑人（RR，0.65；95% CI，0.62-0.68）和西班牙裔（RR，0.88；95% CI，0.82-0.94）退伍军人接受诊断测试的可能性较小。患有便血的退伍军人大多是白人（105341 [55.7%]）。在患有便血的退伍军人中，30至49岁的人比30岁以下的成年人更有可能接受诊断检测（30-39岁：RR，1.15；95% CI，1.12-1.18；40-49岁） ：RR，1.36；95% CI，1.33-1.40）。与患有便血的白人退伍军人相比，患有便血的西班牙裔退伍军人接受诊断测试的可能性较小（RR，0.96；95% CI，0.93-0.98）。 在患有 IDA 和/或便血的 50 岁以下退伍军人队列中，诊断测试完成率低。患有 IDA 的女性、黑人和西班牙裔退伍军人以及患有便血的西班牙裔退伍军人的随访可能性较小。优化跨社会和人口群体的及时随访可能有助于改善结直肠癌的结果并缩小差异。

To date, the diagnostic test completion rate and the time to diagnostic endoscopy or colonoscopy among adults with iron-deficiency anemia (IDA) and/or hematochezia have not been well characterized.To evaluate the diagnostic test completion rate and the time to diagnostic testing among veterans younger than 50 years with IDA and/or hematochezia.This cohort study was conducted within the Veterans Health Administration between October 1, 1999, and December 31, 2019, among US veterans aged 18 to 49 years from 2 separate cohorts: those with a diagnosis of IDA (n = 59 169) and those with a diagnosis of hematochezia (n = 189 185). Statistical analysis was conducted from August 2021 to August 2023.Diagnostic testing factors included age, sex, race and ethnicity, Veterans Health Administration geographic region, and hemoglobin test value (IDA cohort only).Primary outcomes of diagnostic testing were (1) bidirectional endoscopy after diagnosis of IDA and (2) colonoscopy or sigmoidoscopy after diagnosis of hematochezia. The association between diagnostic testing factors and diagnostic test completion was examined using Poisson models.There were 59 169 veterans with a diagnosis of IDA (mean [SD] age, 40.7 [7.1] years; 30 502 men [51.6%]), 189 185 veterans with a diagnosis of hematochezia (mean [SD] age, 39.4 [7.6] years; 163 690 men [86.5%]), and 2287 veterans with IDA and hematochezia (mean [SD] age, 41.6 [6.9] years; 1856 men [81.2%]). The cumulative 2-year diagnostic workup completion rate was 22% (95% CI, 22%-22%) among veterans with IDA and 40% (95% CI, 40%-40%) among veterans with hematochezia. Veterans with IDA were mostly aged 40 to 49 years (37 719 [63.7%]) and disproportionately Black (24 480 [41.4%]). Women with IDA (rate ratio [RR], 0.42; 95% CI, 0.40-0.43) had a lower likelihood of diagnostic test completion compared with men with IDA. Black (RR, 0.65; 95% CI, 0.62-0.68) and Hispanic (RR, 0.88; 95% CI, 0.82-0.94) veterans with IDA were less likely to receive diagnostic testing compared with White veterans with IDA. Veterans with hematochezia were mostly White (105 341 [55.7%]). Among veterans with hematochezia, those aged 30 to 49 years were more likely to receive diagnostic testing than adults younger than 30 years of age (age 30-39 years: RR, 1.15; 95% CI, 1.12-1.18; age 40-49 years: RR, 1.36; 95% CI, 1.33-1.40). Hispanic veterans with hematochezia were less likely to receive diagnostic testing compared with White veterans with hematochezia (RR, 0.96; 95% CI, 0.93-0.98).In the cohorts of veterans younger than 50 years with IDA and/or hematochezia, the diagnostic test completion rate was low. Follow-up was less likely among female, Black, and Hispanic veterans with IDA and Hispanic veterans with hematochezia. Optimizing timely follow-up across social and demographic groups may contribute to improving colorectal cancer outcomes and mitigate disparities.