Weight loss since early adulthood, later life risk of fracture hospitalizations, and bone mineral density: a prospective cohort study of 0.5 million Chinese adults

SUMMARY: In a Chinese population from both urban and rural areas, weight loss of ≥ 5 kg from early adulthood to midlife was associated with a higher risk of hip fracture and lower BMD in later life. INTRODUCTION: This study investigates the association of the long-term weight loss from young adulthood through the middle ages with the subsequent 10-year risk of hospitalized fracture and calcaneus bone mineral density (BMD). METHODS: China Kadoorie Biobank (CKB) was established during 2004–2008 in ten areas across China. Weight at age 25 years was self-reported at baseline, and weight at baseline and resurvey was measured by the calibrated equipment. Outcomes were hospitalized fracture during follow-up and calcaneus BMD measured at resurvey. Analysis for fracture risk included 411,812 participants who were free of fracture in the last 5 years before baseline, cancer, or stroke at any time before baseline. Analysis for BMD included 21,453 participants who participated in the resurvey of 2013–2014 with the same exclusion criteria as above. RESULTS: The mean age was 50.8 at baseline and 58.4 at resurvey. Median weight change from age 25 to baseline was 4.4 kg, with 20.7% losing weight and 58.5% gaining weight. During a median follow-up of 10.1 years, we documented 13,065 cases of first diagnosed fracture hospitalizations, including 1222 hip fracture. Compared with participants whose weight was stable (± 2.4 kg), the adjusted hazard ratios (95% CIs) for those with weight loss of ≥ 5.0 kg from age 25 to baseline was 1.39 (1.17 to 1.66) for hip fracture. Weight loss was not associated with fracture risk at other sites. Those with weight loss from age 25 to resurvey had the lowest BMD measures, with β (95% CIs) of − 4.52 (− 5.08 to − 3.96) for broadband ultrasound attenuation (BUA), − 4.83 (− 6.98, − 2.67) for speed of sound (SOS), and − 4.36 (− 5.22, − 3.49) for stiffness index (SI). CONCLUSIONS: Weight loss from early adulthood to midlife was associated with a higher risk of hip fracture and lower BMD in later life. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11657-020-00734-3) contains supplementary material, which is available to authorized users.