Supplementary Material for: Heterogeneity of Frailty Trajectories and Associated Factors in the Lothian Birth Cohort 1936

Introduction: Recent research suggests that the experience of frailty progression may be heterogeneous, with latent subpopulations of older adults following distinct trajectories of frailty. We aimed to investigate this notion and determine whether certain factors are associated with the membership of these subpopulations. Methods: Data from 5 data waves collected over 12 years in participants of the Lothian Birth Cohort 1936, aged 70 at baseline, were used to derive the frailty index (FI) (NW1 = 1,091, NW5 = 431). These were used in latent class mixed modelling to estimate subpopulations of frailty trajectories. Results: A quadratic latent class mixed model found 3 distinct groupings, which followed a low (61%, n = 632), medium (36%, n = 368), or high (3%, n = 28) FI trajectory. Each grouping had different intercepts and slopes, with the high grouping following the steepest trajectory indicating a rapid increase in frailty. Findings showed that in general, those in the low grouping were younger, had higher education, higher age 11 cognitive ability, and were from a higher social class than those in the medium and high groupings. Discussion/Conclusion: Our findings demonstrate heterogeneity in frailty trajectories over 12 years in individuals aged 70 years at baseline. Membership of higher frailty trajectory groupings was associated with lower social class, less education, and lower childhood cognitive ability, indicating the potential for future interventions to target individuals who are at the greatest risk of belonging to the high frailty trajectory. Future research is required to continue this line of inquiry by exploring other risk and protective factors, and importantly, to assess whether it is possible to realign an individual’s membership to a less detrimental grouping of frailty trajectory.引言：近期研究表明，衰弱进展的表现存在异质性，老年人群的潜在亚群会遵循不同的衰弱轨迹。本研究旨在验证这一观点，并探究特定因素是否与这些亚群的归属相关。 方法：研究使用了洛锡安1936年出生队列（Lothian Birth Cohort 1936）参与者在12年间收集的5次数据波信息，该队列参与者基线年龄为70岁，用于构建衰弱指数（FI）（NW1=1,091，NW5=431）。将上述数据用于潜类别混合模型（latent class mixed modelling）以估算衰弱轨迹的亚群。 结果：二次潜类别混合模型识别出3个不同的分组，分别遵循低（61%，n=632）、中（36%，n=368）或高（3%，n=28）衰弱指数轨迹。每个分组的截距与斜率均存在差异，其中高衰弱指数分组的轨迹最为陡峭，提示衰弱程度快速上升。研究结果显示，整体而言，低衰弱指数分组的参与者相较于中、高分组参与者更年轻、受教育程度更高、11岁时的认知能力更强，且社会阶层更高。 讨论与结论：本研究结果证实，基线年龄为70岁的人群在12年间的衰弱轨迹存在异质性。归属更高衰弱轨迹分组的个体往往社会阶层更低、受教育程度更低、儿童时期认知能力更差，这提示未来可针对高衰弱轨迹高风险人群开展干预措施。未来需开展进一步研究，探索其他风险与保护因素以延续该研究方向；尤为重要的是，需评估是否可将个体的衰弱轨迹分组重新归类至危害性更低的组别。