Supplementary Material for: Obesity Prevalence in the Long-Term Future in 18 European Countries and in the USA

<b><i>Introduction:</i></b> Obesity constitutes a major public health problem in Europe, but how the obesity epidemic in European countries will evolve remains unknown. Most previous obesity projections considered the short-term future only, focused on single non-European countries, and projected ongoing increases foremost. We comparatively project obesity prevalence into the long-term future for 18 European countries and the USA. <b><i>Data:</i></b> We used national age-specific (20–84 years) and sex-specific obesity prevalence estimates (1975–2016) from the NCD Risk Factor Collaboration (NCD-RisC) 2017 study, which are based on available measured height and weight data, supplemented with estimates from a Bayesian hierarchical model. <b><i>Methods:</i></b> We projected age- and sex-specific obesity prevalence up to the year 2100 by integrating the notion of a wave-shaped obesity epidemic into conventional age-period projections. <b><i>Results:</i></b> In 1990–2016, the increasing trends in obesity prevalence were decelerating. Obesity is expected to reach maximum levels between 2030 and 2052 among men, and between 2026 and 2054 among women. The maximum levels will likely be reached first in The Netherlands, USA, and UK, and last in Switzerland; and are expected to be highest in the USA and UK, and lowest in The Netherlands for men and Denmark for women. In 2060, obesity prevalence is expected to be lowest among Dutch men and highest among Swiss men. The projected age-specific obesity prevalence levels have an inverse U-shape, peaking at around the age of 60–69 years. <b><i>Discussion:</i></b> Applying our novel approach to the NCD-RisC 2017 data, obesity prevalence is expected to reach maximum levels between 2026 and 2054, with the USA and UK reaching the highest maximum levels first, followed by other European countries.

**引言：** 肥胖已成为欧洲地区的重大公共卫生挑战，然而欧洲各国的肥胖流行态势将如何演进，目前仍无定论。既往多数肥胖流行预测研究仅聚焦短期未来，且仅针对单个非欧洲国家展开，其核心预测结论多为患病率将持续上升。本研究针对18个欧洲国家及美国，对其肥胖患病率开展了长期对比预测。
**数据：** 本研究采用了非传染性疾病风险因素协作组（NCD Risk Factor Collaboration, NCD-RisC）2017年研究中的全国分年龄（20~84岁）、分性别肥胖患病率估计数据（1975~2016年），该数据集基于已公开的实测身高与体重资料，并辅以贝叶斯分层模型（Bayesian hierarchical model）生成的估计值进行补充完善。
**方法：** 本研究将肥胖流行呈波浪形演变的核心理念融入传统年龄-时期预测模型，对20~84岁分年龄、分性别的肥胖患病率进行了直至2100年的预测。
**结果：** 1990~2016年间，肥胖患病率的上升趋势已出现明显放缓。预计男性肥胖患病率将在2030~2052年间达到峰值，女性则将在2026~2054年间达到峰值。各国中，荷兰、美国与英国将率先迎来肥胖患病率峰值，瑞士则将最晚达到该峰值；男性肥胖患病率峰值将以美国与英国为最高，荷兰为最低；女性峰值则以丹麦为最低。至2060年，荷兰男性的肥胖患病率预计将处于最低水平，瑞士男性则将处于最高水平。本次预测得到的分年龄肥胖患病率呈倒U型分布，峰值年龄段约为60~69岁。
**讨论：** 将本研究提出的新型分析方法应用于NCD-RisC 2017数据集后，结果显示肥胖患病率预计将在2026~2054年间达到峰值，其中美国与英国将率先达到最高峰值，其余欧洲国家将紧随其后。