Risk of Fractures in Thyroid Cancer Patients With Postoperative Hypoparathyroidism: A Nationwide Cohort Study in Korea.

Postoperative hypoparathyroidism (PO-hypoPT) is an uncommon complication of total thyroidectomy in thyroid cancer patients. Although long-term hypoPT causes characteristic changes in bone metabolism, the risk of fractures in hypoPT remains inconclusive. We investigated the risk of fractures in Korean thyroid cancer patients with PO-hypoPT. This was a retrospective cohort study using data from the Korea Central Cancer Registry and Korean National Health Insurance Service. We analyzed 115,821 thyroid cancer patients aged ≥18 years, who underwent total thyroidectomy between 2008 and 2016. The risk of any fractures, including vertebral, hip, humerus, and wrist fractures, according to parathyroid function after total thyroidectomy, was analyzed using the multivariable Cox proportional hazard model. The PO-hypoPT and preserved parathyroid function groups included 8789 (7.6%) and 107,032 (92.4%) patients, respectively. Over a mean follow-up duration of 4.8 years, 159 (1.8%) and 2390 (2.2%) fractures occurred in the PO-hypoPT and preserved parathyroid function groups, respectively. The risk of any fractures was significantly lower in the PO-hypoPT group than in the preserved parathyroid function group (hazard ratio [HR] = 0.83; 95% confidence interval [CI] 0.70-0.98; p = 0.037) after adjusting for confounders. Regarding the fracture site, only the risk of vertebral fractures was significantly lower in the PO-hypoPT group compared with the preserved parathyroid function group (HR = 0.67; 95% CI 0.47-0.96; p = 0.028) after adjusting for confounders. Subgroup analyses showed that bone mineral density measurements and calcium supplementation interacted with the relationship between PO-hypoPT and the risk of any fractures (p for interactions = 0.010 and 0.017, respectively). PO-hypoPT was associated with a lower risk of fractures in thyroid cancer patients, especially at the vertebra. The relatively low bone turnover caused by PO-hypoPT and appropriate management for PO-hypoPT with active vitamin D and calcium may prevent the deterioration of skeletal health in thyroid cancer patients who can easily be exposed to long-term overtreatment with levothyroxine. © 2023 American Society for Bone and Mineral Research (ASBMR).

Incidence and mortality of subsequent vertebral fractures: analysis of claims data of the Korea National Health Insurance Service from 2007 to 2016.

BACKGROUND CONTEXT: Vertebral fracture is related to an increased risk for subsequent and recurrent osteoporotic fracture as well as increased mortality. However, no study has investigated the exact incidence and mortality of subsequent vertebral fractures. OBJECTIVE: The purpose of our study was to determine trends in the incidence and mortality of subsequent vertebral fractures after first-time vertebral fracture in Koreans older than 50 years using the national claims database. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Data from the Korea National Health Insurance Service database from 2007 to 2016. OUTCOME MEASURES: The incidence of subsequent vertebral fracture during a 4-year follow-up period. The mortality and standardized mortality ratio (SMR) after subsequent vertebral fractures during the 1-year period after fracture were also determined. Analysis was restricted to patients older than 50 years. METHODS: The national claims data set was analyzed to find all new visits and revisits after 6 months from the last claim to a hospital or clinic for vertebral fractures and revisits in men and women aged 50 years or older between 2007 and 2016. The number of first-time vertebral fractures in 2012 was investigated to determine subsequent vertebral fractures. The incidence, mortality rates, and SMR of subsequent vertebral fractures were calculated. There were no sources of funding and no conflicts of interest associated with this study. RESULTS: During the 4-year follow-up period, the overall cumulative incidence of subsequent vertebral fractures were 27.53%. According to sex, the cumulative incidence of subsequent vertebral fractures was 20.09% in men and 29.98% in women. The cumulative mortality rate over the first year after subsequent vertebral fractures was 5%. The mortality rates over 1 year were 10.04% for men and 3.81% for women. The overall SMR at the 1-year follow-up after subsequent vertebral fractures was 10.58 (95% confidence interval: 9.29-12.05) in men and 3.88 (95% confidence interval: 3.5-4.3) in women. CONCLUSIONS: Our study showed that subsequent vertebral fractures were more common in women, with an incidence rate of 29.98% over 4 years. However, the mortality rate was higher in men, reaching 10.04% in 1 year. Subsequent vertebral fractures occurred in large numbers, and the mortality rates were relatively high. Thus, first vertebral fracture may be considered as an early warning of high risk for future subsequent vertebral fractures, especially in women.

Free Fatty Acid Receptor 4 (GPR120) Stimulates Bone Formation and Suppresses Bone Resorption in the Presence of Elevated n-3 Fatty Acid Levels.

Free fatty acid receptor 4 (FFA4) has been reported to be a receptor for n-3 fatty acids (FAs). Although n-3 FAs are beneficial for bone health, a role of FFA4 in bone metabolism has been rarely investigated. We noted that FFA4 was more abundantly expressed in both mature osteoclasts and osteoblasts than their respective precursors and that it was activated by docosahexaenoic acid. FFA4 knockout (Ffar4(-/-)) and wild-type mice exhibited similar bone masses when fed a normal diet. Because fat-1 transgenic (fat-1(Tg+)) mice endogenously converting n-6 to n-3 FAs contain high n-3 FA levels, we crossed Ffar4(-/-) and fat-1(Tg+) mice over two generations to generate four genotypes of mice littermates: Ffar4(+/+);fat-1(Tg-), Ffar4(+/+);fat-1(Tg+), Ffar4(-/-);fat-1(Tg-), and Ffar4(-/-);fat-1(Tg+). Female and male littermates were included in ovariectomy- and high-fat diet-induced bone loss models, respectively. Female fat-1(Tg+) mice decreased bone loss after ovariectomy both by promoting osteoblastic bone formation and inhibiting osteoclastic bone resorption than their wild-type littermates, only when they had the Ffar4(+/+) background, but not the Ffar4(-/-) background. In a high-fat diet-fed model, male fat-1(Tg+) mice had higher bone mass resulting from stimulated bone formation and reduced bone resorption than their wild-type littermates, only when they had the Ffar4(+/+) background, but not the Ffar4(-/-) background. In vitro studies supported the role of FFA4 as n-3 FA receptor in bone metabolism. In conclusion, FFA4 is a dual-acting factor that increases osteoblastic bone formation and decreases osteoclastic bone resorption, suggesting that it may be an ideal target for modulating metabolic bone diseases.

Higher serum carcinoembryonic antigen levels associate with more frequent development of incident fractures in Korean women: a longitudinal study using the national health insurance claim data.

BACKGROUND: Pro-inflammatory cytokines play important roles in bone metabolism and several studies have shown that carcinoembryonic antigen (CEA) may promote inflammation. We investigated the association of serum CEA levels with the risk of osteoporosis and incident fracture. METHODS: We performed a small cross-sectional study with 302 Korean women and a large, longitudinal study with 7192 Korean women in an average 3-year follow-up period. For the cross-sectional study, bone mineral density (BMD) and bone turnover markers (BTMs) were measured. For the longitudinal study, incident fractures in the follow-up period were identified by using the selected International Classification of Diseases, 10th revision (ICD-10) codes and the nationwide claims database of the Health Insurance Review and Assessment Service of Korea. RESULTS: In the cross-sectional study, serum CEA levels correlated negatively with BMD at the lumbar spine (γ=-0.023; P=0.029) and positively with BTMs (γ=0.122 to 0.138, P=0.002 to P<0.001) after adjustment for confounding variables. In the longitudinal study, 254 (3.5%) women developed incident fractures in the follow-up period (2.8±1.3 years). After adjustment for potential confounders, the hazard ratio (HR) per 1 ng/mL increment of the baseline CEA level for the development of incident fracture was 1.22 [95% confidence interval (CI): 1.05-1.42]. The HR was markedly higher in subjects in the highest CEA quartile category compared with those in the lowest CEA quartile category (HR=1.54, 95% CI: 1.04-2.28). CONCLUSION: Therefore, serum CEA may be a biomarker of the risk of incident fracture in postmenopausal Korean women.

Association between metabolic syndrome and incident fractures in Korean men: a 3-year follow-up observational study using national health insurance claims data.

CONTEXT: Although the prevalence of both metabolic syndrome (MetS) and fractures increases with advancing age, studies on possible associations between these conditions in men are limited and the results are inconsistent. OBJECTIVE: The objective of the study was to clarify the impact of MetS on the male risk of incident fractures. DESIGN AND SETTING: This was a large, longitudinal study with an average 3-year follow-up period. PARTICIPANTS: Korean men (n = 16 078) aged 50 years or older who had undergone comprehensive routine health examinations participated in the study. MAIN OUTCOME MEASURES: Incident fractures found after baseline examinations were identified using selected International Classification of Diseases, tenth revision, codes in the nationwide claims database of the Health Insurance Review and Assessment Service of Korea. RESULTS: In total, 158 men (1.0%) developed incident fractures. The fracture event rates for subjects with and without MetS were 26.2 and 35.7 per 10 000 person-years, respectively. After adjustment for potential confounders, subjects with MetS had a much lower risk of incident fractures than subjects without MetS (hazard ratio 0.662, 95% confidence interval 0.445-0.986). Furthermore, subjects with three and four or more MetS components had a 49.4% and 50.4% lower risk, respectively, of incident fractures compared with the subjects without any MetS components. Importantly, additional adjustment for body mass index eliminated the statistical significance of these associations. CONCLUSION: Our current results indicate that the beneficial effects of MetS in reducing fracture risk could be explained by the general obesity that accompanies MetS, although other related factors, such as greater padding effect, peripheral aromatization, or adipokine changes, may also contribute.