Incidence rates and life-time risk of hip fractures in Mexicans over 50 years of age: a population-based study
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- Clark, P., Lavielle, P., Franco-Marina, F. et al. Osteoporos Int (2005) 16: 2025. doi:10.1007/s00198-005-1991-4
The vast majority of hip fractures in the 21st century will occur in the developing countries. The rates and life-time hip fracture risk are not known for Mexico, and for this reason, we studied the incidence of hip fractures, and the remaining life-time probability of having a hip fracture at the age of 50 years in Mexican men and women. All hip fracture cases registered during the year 2000 were collected at all the main tertiary-care hospitals in the two major health systems in México City, Instituto Mexicano del Seguro Social (IMSS) and Ministry of Health (SS), and the diagnosis was validated by chart review in all cases. The annual rates of hip fracture were 169 in women and 98 in men per 100,000 person-years. The life-time probability of having a hip fracture at 50 years of age was 8.5% in Mexican women and 3.8% in Mexican men. We conclude that hip fractures are an important health problem in Mexico and that Mexican health authorities should consider public health programs to prevent hip fractures.
KeywordsEpidemiologyHip fracturesLife-time riskMéxicoPopulation studiesPrevalence
Hip fractures are the most serious consequence of osteoporosis. These types of fracture are associated with very high morbidity and mortality rates. Hip fractures are the international barometer of the impact of osteoporosis because of their severe socioeconomic costs and because they are more easily documented than other fractures and can be used to compare rates in different countries . Worldwide projections for the number of hip fractures indicate an increase from 1.2 million in the 1990s to 2.6 million by the year 2025 and to 4.5 million by the year 2050, assuming no change in the age- and sex-specific incidence. These figures could be higher (range of 7.3–21.3 million) if small secular trends occur. Most of these fractures will occur in the developing world . The two main factors contributing to the burden of hip fractures are the increasing population over 65 years of age, and the increase in life expectancy in most populations.
Information about osteoporosis and fractures in México is scarce; according to the World Health Organization (WHO), more than 1 million Mexican women could have osteoporosis , representing around 15% of women aged 50 years or more. This figure is similar from a recent study (LAVOS) in which 16% of a random sample of community-dwelling women over 50 years had osteoporosis based on hip bone mineral density (BMD) (approximately 1.5 million) . Reports from the Mexican Health Ministry Epidemiology Surveillance System (SS) in México show that fractures in individuals over 60 years old represented the fourth-most frequent discharge diagnosis between the years 1993 and 2001 (9.9% among 606,104 hospitalized cases) [5,6]. An incidence rate of 160/100,000 fractures per year for individuals aged 50 years and older has been reported at the tertiary-level hospitals of the Mexican Institute of Social Security (IMSS) in 1988 . Population incidence rates of hip fracture have never been determined for México. The objectives of the present study were to determine rates of hip fracture and to estimate life-time risk probability for hip fractures in Mexicans over 50 years of age.
The two largest public health care systems within México are the Mexican Institute of Social Security (IMSS) and the Ministry of Health (SS). The IMSS coverage includes all formally employed workers and their families, and delivers health care to nearly 50 million Mexicans (approximately half of the population); the SS delivers health to uninsured people through health care facilities owned and operated by them directly and delivers care to nearly 48 million Mexicans . For the purpose of this study, we included all hospitals with surgical facilities to perform hip surgery from the Mexican Institute of Social Security and the Ministry of Health located in the México City area. Eleven hospitals fulfilled these criteria and nine were selected for the study. One hospital was closed throughout the year 2000. Another hospital did not participate in the study, but usually referred its cases to the other hospitals. It has been estimated that approximately 2% of the population receive health care through private systems .
From January 1 to December 31, 2000, we identified all hip fracture cases in individuals 50 years and older registered at the emergency rooms and surgical departments of all nine selected hospitals. Charts were retrieved and age, sex, type of fracture, and place of residence were extracted in all cases. The initial diagnoses were verified by surgical reports and/or X-rays by two of the investigators of the study (P.L. and E.R.). Individuals whose residence was not in the México City area were excluded. The following fractures using the ICD-10 classification were included: S72.0 Femoral neck fracture, S72.1 Peritrochanteric fracture (intertrochanteric fracture and trochanteric fracture), and S72.2 Subtrochanteric fracture.
Age- and sex-specific hip fracture incidence rates per 100,000 person-years were calculated and presented in 10-year intervals along with their confidence intervals. The numerator was defined as the number of hip fractures registered and confirmed by medical chart reviewing in the hospitals selected for the study. The denominator was obtained from a 10% random sample of the 2000 Mexican Population Census, considering only the population in México City that reported IMSS and Health Ministry health care facilities as their regular source of health care using the sex and age distribution of individuals 50 years and over. To be able to compare our results with other studies, our overall incidence rates were age-adjusted through the direct method, using the 1990 non-Hispanic white US population as standard .
For estimating the life-time risk of having a hip fracture in women and men aged 50 years or older, we calculated age- and sex-specific death rates for the whole country, using official death counts and denominators . Life-time risk probabilities were computed from the hazard functions of hip fracture and death using the method of Kanis and colleagues .
A total of 1,137 cases of hip fracture were registered in the year 2000 from the selected hospitals, of which 1,067 cases were reviewed (70 charts [6.1%] were not available) including 748 women (70.1%) and 319 men (29.9%) (F/M Ratio 2.3:1)
Sex- and age-specific incidence rates of hip fractures in México City, 2000*( CI confidence interval)
Age group (years)
Total number of cases
Annual rate (per 100,000 person-years)
Men (95% CI)
Woman (95% CI)
Hip fracture rates were similar in men and women 50–59 years of age, but after this age, incidence rates were consistently higher in women. Hip fracture rates in both sexes increased in an exponential pattern from 20 per 100,000 for both sexes from ages 50–59 years, to 688/100,000 and 1,137/100,000 in men and women, respectively, in the 80-year-and-older group. The types of hip fractures found were 63% transtrochanteric, 33% cervical and 4% subtrochanteric.
The life-time risk of sustaining a hip fracture at the age of 50 years in Mexicans was 8.5% in women and 3.8% in men.
This is the first population-based study of the hip fracture incidence rates and the life-time risk probability of having a hip fracture after 50 years of age in the Mexican population in both sexes. Our results indicate that, for 50-year-old Mexican women living in Mexico City, about one of every 12 will suffer a hip fracture during their remaining life time. Thus, hip fracture is one of the most common and important threats to the health and independence of urban Mexican women. The risks of hip fracture are about half as great in men, but the 4% life-time risk indicates that hip fracture is also a common and important condition in Mexican men.
Age- and sex-specific incidence rates (per 100,000) of hip fracture
Geographic area, years of survey, (reference number)
Women, age (years)
Men, age (years)
Age-standardized rate (per 100,000)
Whites, Olmsted, Minnesota, USA 1989–91 
Blacks, California, USA, 1983–84 
Asians, California, USA, 1983–84 
Hispanics, California, USA, 1983–84 
Central Norway, 1983–84 
Malmo, Sweden, 2002 
Former West Germany, 1996 
Former East Germany, 1996 
Spain, Medos, 1994 
Hong Kong, 1997–1998 
Singapore, 1997–1998 
Thailand, 1997–1998 
Malaysia 1997–1998 
Beijing, 1996 
Argentina, La Plata, 1989–90 
México City, 2000
The Mexican age-adjusted standardized rates with non-Hispanic US population and comparison with some other countries are presented also in Table 2. The trends follow the same pattern as described above.
Life-time risk of hip fracture in Mexican population compared with selected countries
Life-time risk at 50 years %
China (Hong Kong)*
Many hypotheses have been proposed to explain the wide variation in hip fracture incidence rates and life-time risk found among different countries. Such heterogeneity can be explained mainly by two factors: First, the variation in the rates might reflect true differences between populations (race and genetics) and in their exposure to different risk factors. Risk factors include geographical latitude, sun exposure, Vitamin D deficiency, bone strength and bone geometry, fragility, risk of falling, prenatal nutrition, all of which could affect the risk of fractures in later life. Life-style factors such as physical activity, diet and smoking might also contribute [1,15]. Ecological studies do not suggest important roles for these risk factors with the possible exception of physical activity on the risk of falling . Second, there are some inherent limitations using discharge data and national databases that might partially explain the variation in rates: the accuracy of health statistics may differ from one country to another, and there are no estimates of the error of using these sources. Not all studies included the ICD code for definition of cases; and no validation of cases was attempted in some of the studies. Miscoding, multiple counts, and selection of study populations could also play a role in these differences [11, 13,16]. Nevertheless, there are greater than tenfold differences in fracture incidence, which are much larger than the errors. Indeed, wide variations of this magnitude are reported from prospective studies in Europe using the same methodology .
We speculate that the rates of hip fracture in Mexico are similar to those found in some Asians and Hispanics residing in the USA because they share Western lifestyles, including Western diets and more sedentary occupations. Mexican rates are also similar to Spain, perhaps because of the genetic background that Mexicans share with Spaniards (Mexican mestizo is the mixture of Spaniards and the indigenous population of Mesoamerica). Mexican rates are lower than the rates observed in Northern European countries and white Americans in the USA, as expected, since these countries have always reported the highest rates. Similar trends are observed using age-adjusted hip fracture rates, and, therefore, differences in the age structure of the compared populations do not explain the mentioned trends.
This study has several strengths. We double-checked from emergency room lists at all hospitals selected in order not to lose misclassified cases at the discharge registers, and charts were retrieved to verify the diagnoses using surgery logs and/or X-rays. Also, we used comprehensive census data as our denominator and mortality rates for the same year for estimation of life-time risk probabilities. The estimation of life-time risk probabilities using the same methodology to report international variations as used by Kanis and colleagues  allowed us to make reasonable comparisons between our population and those reported by the same author.
This study also has limitations. We studied rates in Mexico City and it is possible that rates will be somewhat different in rural areas of Mexico and may differ from north to south, due to latitude, sun exposure or socioeconomic aspects. Our rates are based on the IMSS and SS systems, which cover over 95% of the Mexican population . Although we attempted to include data from the private systems and gathered hip fracture cases from three large private hospitals in Mexico City in the same fashion as we did for the public systems, the lack of a suitable denominator for individuals who use private health care system in México precluded their inclusion in the study. However, the number of cases collected in private hospitals was less than 1% of the total numbers observed in the public systems and this would, therefore, have no significant impact on our estimates of rates.
Despite the above considerations, we believe that hip fracture rates and life-time probabilities are appropriate measures that help characterize the burden of hip fractures in a country. The estimates in the present study, when compared with similar international studies, place the Mexican population at an intermediate risk for hip fractures and at a medium risk for life-time probabilities for the year 2000. Hip fracture risk can also serve as a parameter of fragility fractures, since there appears to be a consistent relationship between hip fracture risk and the risk of other fragility fractures .
Developing countries are expected to have a demographic shift over the next 50 years, due to an increasing elderly population. It is expected that 75% of the burden from hip fractures will come from these countries and the remaining 25% from the developed world, in which a stabilization of hip fractures rates or even a decrease in rates has been documented [18–20]. In Mexico, there were an estimated 2.6 million women aged 65 years or more in the year 2000. Whereas, the overall population is set to increase by 29% in the year 2005, the female population aged 65 years or more will increase by 270% to 7.1 million. In the year 2050, this figure will reach 21.1 million . Affordable strategies for detection of populations at risk, as well as the development of strategies for primary and secondary prevention, need to be implemented urgently in order to prevent a future epidemic of fragility fractures in México and many other developing counties.
Increasing development and westernization are likely to increase the rate of hip fractures in Mexico, and the growing numbers of elderly in Mexico means that hip fractures will be a growing problem for the Mexican health care system. These results should be used to alert the general population, health institutions, and health policy decision makers in order to start planning and implementing the strategies needed to detect the population at risk and to implement primary and secondary prevention programs and allocation of resources to overcome osteoporotic fractures in México’s future.
We are grateful to Helena Johansson for the invaluable assistance estimating the life-time risk probabilities for the Mexican population and to Mrs. Susan Orlofsky for English editing. This study was supported by the University of California Institute for México and the United States (UC-Mexus) CN01/92