The Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, PA.
Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD; Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins University, Baltimore, MD.
Ann Epidemiol. 2020 May;45:40-46.e4. doi: 10.1016/j.annepidem.2020.03.010. Epub 2020 Apr 3.
Cohort participants usually have lower mortality rates than nonparticipants, but it is unclear if this survival advantage decreases or increases as cohort studies age.
We used a 1975 private census of Washington County, Maryland, to compare mortality among cohort participants to nonparticipants for three cohorts, Campaign Against Cancer and Stroke (CLUE I), Campaign Against Cancer and Heart Disease (CLUE II), and Atherosclerosis Risk In Communities (ARIC) initiated in 1974, 1989, and 1986, respectively. We analyzed mortality risk using time-truncated Cox regression models.
Participants had lower mortality risk in the first 10 years of follow-up compared with nonparticipants (fully adjusted average hazard ratio [95% confidence intervals] were 0.72 [0.68, 0.77] in CLUE I, 0.69 [0.65, 0.73] in CLUE II, and 0.74 [0.63, 0.86] in ARIC), which persisted over 20 years of follow-up (0.81 [0.78, 0.84] in CLUE I, 0.87 [0.84, 0.91] in CLUE II, and 0.90 [0.83, 0.97] in ARIC). This lower average hazard for mortality among participants compared with nonparticipants attenuated with longer follow-up (0.99 [0.96, 1.01] after 30+ years in CLUE I, 1.02 [0.99, 1.05] after 30 years in CLUE II, and 0.95 [0.89, 1.00] after 30+ years in ARIC). In ARIC, participants who did not attend visits had higher mortality, but those who did attend visits had similar mortality to the community.
Our results suggest the volunteer selection for mortality in long-standing epidemiologic cohort studies often diminishes as the cohort ages.
与非参与者相比，队列参与者的死亡率通常较低，但尚不清楚这种生存优势随着队列研究的老化是减少还是增加。
我们使用 1975 年马里兰州华盛顿县的私人普查数据，对三个队列的队列参与者与非参与者的死亡率进行了比较，这三个队列分别是 1974 年启动的癌症和中风防治运动（CLUE I）、癌症和心脏病防治运动（CLUE II）和社区动脉粥样硬化风险研究（ARIC）。我们使用时间截断的 Cox 回归模型分析了死亡率风险。
与非参与者相比，参与者在前 10 年的随访中死亡率较低（完全调整后的平均风险比[95%置信区间]在 CLUE I 中为 0.72[0.68,0.77]，在 CLUE II 中为 0.69[0.65,0.73]，在 ARIC 中为 0.74[0.63,0.86]），这种情况持续了 20 多年的随访（CLUE I 中为 0.81[0.78,0.84]，CLUE II 中为 0.87[0.84,0.91]，ARIC 中为 0.90[0.83,0.97]）。与非参与者相比，参与者的平均死亡率风险随着随访时间的延长而降低（CLUE I 中 30 年以上为 0.99[0.96,1.01]，CLUE II 中 30 年以上为 1.02[0.99,1.05]，ARIC 中 30 年以上为 0.95[0.89,1.00]）。在 ARIC 中，未参加就诊的参与者死亡率较高，但参加就诊的参与者死亡率与社区相似。
我们的研究结果表明，在长期的流行病学队列研究中，由于志愿者的选择，死亡率通常会随着队列的老化而降低。
