As the global aging process accelerates, the incidence and disease burden of hip fractures will remain significant in future. Through the research, we described the time trends and regional distribution of hip fractures, and explored the main causes, which will help provide more accurate directions for governments, hospitals, and communities to reduce the disease burden. Using the data from the GBD 2021, we found that the global incidence and burden of hip fractures in 2021 remains high. The incidence was positively associated with SDI, while there was no such association with years of disability survival. The majority of hip fractures occurred in people over 70 years of age, and female gained higher incidence and YLD. Falls were main cause of hip fractures, so strengthening the prevention of falls and osteoporosis is particularly important for decreasing the disease burden in future.
Limitation
As with other GBD estimation studies, our study also has limitations. The first limitation is the quality and collection of raw data. The data of GBD database most come from the national and regional reports, rather than directly from the country government's report, which will lead to problems about data integrity and circulation process. Although the GBD 2021 research team continued to strengthen the data collection system, it remains difficult to eliminate data instability due to inconsistent availability of key epidemiological data, especially in low SDI countries with inadequate health care systems. Secondly, due to the different medical levels, different countries and regions had different records and reports on disease data, which resulted in the absence of some original disease data. The data are not enough to estimate the burden of disease for the 204 countries and regions, so the estimates of the burden of disease for hip fractures in areas with inadequate medical care are subject to large errors which cannot fully replace primary data with high quality.
Incidence of Hip Fractures
With the rise of global population, the GBD database estimated that the incidence number of hip fractures in 2021 was large that increased by 126.4% compared to 1990. The incidence was positively correlated with age. Because of the influence of the global ageing process, the incidence rate for all ages of hip fracture was rising steadily, while the ASIR remained unchanged basically. There is also a positive correlation between hip fracture incidence and SDI. Oceania and most western developed countries with a high SDI are usually observed the high ASIR, such as Australia, Western Europe and so on. A study on the long-term trends in global hip fractures pointed to urbanization as a possible cause of this correlation [13]. People under the urbanization are more likely to suffer hip fractures due to the decrease of outdoor physical activity, lifestyle changes, calcium and vitamin D deficiencies and so on. Another study on the epidemiology of hip fractures suggested that regional differences in the incidence of hip fracture may be related to latitude [12]. Dong et al. found that the ASIR was positively correlated with the latitude of the country. Unlike in higher latitudes, people in lower latitudes are exposed to more sunlight and have higher bone quality, so that they are less likely to develop risk factors such as osteoporosis that can lead to hip fractures. In conclusion, the high latitude area with urbanization may still be a high-risk area for the incidence in the future. In addition, some common risk factors in areas with high SDI also leads to an increased incidence of hip fracture, such as smoking and drinking a lot [17-19]. Therefore, doing more outdoor activities, increasing the amount of sunlight exposure, avoiding contact with hip fracture risk factors (such as tobacco and alcohol), preventive supplementation of calcium and vitamin D and other methods can effectively reduce the incidence [20].
YLD of Hip Fractures
In terms of burden, the ASYR of patients with hip fractures decreased globally from 1990 to 2021. Nevertheless, trends varying from country to country, many countries also showed an increasing trend, and even in some countries with high SDI. ASIR was positively associated with SDI, while ASYR were not, which suggested that the burden of hip fracture for one was greater in countries with low SDI. The reason for this difference may be that countries with low SDI have a lower level of medical care, and patients in countries with high SDI can get a better prognosis for the same disease. From 2003 to 2005, only 5.3% of patients with hip fracture in the United States chose to go home and treat themselves after discharge, [1] and 52.8% of hip fracture patients went to a professional nursing facility after discharge. Compared with countries with low SDI over the same period, hip fracture patients in these regions were difficult to receive the same quality of care. A prospective multi-center study of hip fracture in India suggested that, only 66.2% of hip fracture patients chose to undergo surgery from January 2012 to April 2014 [21]. Because of the inadequate medical treatment, most patients with hip fracture need to travel a long distance to obtain better treatment, with an average distance for treatment of 86.4 kilometers. Most patients (85.9%) can not be admitted to hospital until 1 day after fracture, while the delayed treatment will further increase the disease burden [22]. Besides, due to the difficulty of surgery, damage, consumption of medical consumables and other factors, The cost of hip fracture surgery is high. In the United States, hip fracture treatment costs $40,000 for the first year and $5,000 per year for subsequent years [1]. Compared with high SDI countries, people in low SDI countries have a low economic level, so it is difficult for ordinary families in low SDI countries to afford such a large sum of money.
For hip fractures, prevention is often more cost-effective than treatment, which can effectively reduce the incidence and burden [23, 24]. Because of the lack of medical conditions and low economic level, the prevention of hip fracture is more important for patients in low SDI countries. With the influence of urbanization, people's lifestyle had changed and resulted in influence of reduced outdoor activity and insufficient light intake, which might result in the increased risk of osteoporosis and result in the occurrence of hip fracture [25-27]. In addition, in some economically backward countries, people do not supplement enough calcium and vitamin D, leading to a higher risk of osteoporosis. According to statistics, there were many vitamin D deficiencies in India at all ages, and more than 80% of urban Indians had serum 25(OH)D levels below 20ng/mL, which would increase risk of osteoporosis and hip fractures [28]. Studies had shown that calcium and micro-nutrient intakes in low-income women in India are severely inadequate [29]. Due to malnutrition, bone mineral content (BMD) and T scores of Indians are much lower compared with developed countries, resulting in an earlier and higher chance of hip fractures in them. Based on these issues, policy measures can be taken to prevent hip fractures. Governments in countries with low SDI can tight their control over food production, fortifying foods such as milk with vitamin D, and increase their focus on malnutrition among adolescents and women [28]. Strengthen the publicity of osteoporosis disease and improve the residents' awareness level of osteoporosis. At the individual level, it is important to ensure adequate calcium and vitamin D intake and increase outdoor activities to ensure adequate sunlight exposure to counter the effects of urbanization [30, 31].
Main Causes
Falls were the main cause of hip fractures with a steady increase of incidence during the past 32 years. Hip fractures attribute to falls are more likely to occur in the elderly, and the prognosis for the elderly tends to be worse than for younger people [32, 33]. Therefore, under the current trend of global aging, it is significant to focus on the prevention of falls among the elderly. Many factors can lead to an increased risk of falls, such as weakness, delirium, medication use (anti-anxiety medications, sedatives, etc.), lack of attendant care, sarcopenia, etc. [34-36]. Through the community, hospitals and nursing institutions, fall prevention measures can be well publicized and implemented, and the prevention awareness of the population can be raised. Staff should choose appropriate preventive measures according to different groups of people. Communities and families should also try to arrange escorts for left-behind elderly people, especially elderly people with mental disorders or insufficient muscle strength. At the same time, it is recommended that the elderly should exercise more to build muscle strength [32, 37, 38].
Incidence and Burden of Hip Fractures by Gender, Age, and SDI
From 1990 to 2021, the incidence and YLD of hip fractures were higher in female, and more patients were over 70 years of age, which is because female have higher risk of osteoporosis than male after menopause due to a drop in estrogen levels [14, 32]. However, it is important to note that the ASIR of hip fractures in men had increased over the past 32 years, suggesting that osteoporosis in older men is generally under-appreciated today. A survey of men with osteoporotic fractures in the United States showed that only less than 6% had bone mineral density measured in the 2 years prior to the fracture, and only 2.1% were diagnosed and treated for osteoporosis [39]. In addition, osteoporosis in men is underdiagnosed and undertreated, resulting in higher rates of disability and death in men despite a lower incidence [14, 24]. Not only for women, the prevention and treatment of hip fractures should be emphasized but also for men [40]. Medical workers should establish complete screening guidelines for male osteoporosis and strengthen the screening of osteoporosis and early anti-osteoporosis treatment. Communities and hospitals need to improve the publicity and education of osteoporosis, in order to strengthen the awareness level of osteoporosis prevention and treatment.