Low incidence of hip fractures in an equatorial area

Hip fractures in patients older than 60 years of age represent a serious morbidity linked to osteoporosis that contributes to its mortality rates. Both genetic and environmental influences have been reported as important factors related to the epidemiology of osteoporosis. Sobral, a city located in the northeast (equatorial zone) of Brazil (3ºS/40ºE) has 138,565 inhabitants, who are mostly white Portuguese and native Brazilian descendants. We evaluated the occurrence of hip fractures in Sobral between July 1996 and June 2000. This was a retrospective cohort-based study. Data were obtained from the medical records of the Santa Casa de Sobral, which is the reference hospital in this area. All chart records of patients aged >20 years with a diagnosis of femoral or hip fracture were revised. A total of 79 fractures were identified. Ten cases (12.6%) that occurred in patients <50 years of age were excluded from further analysis. Sixty-nine cases (87.3%) occurred in patients aged >50 years, comprising 19 (27.5%) men and 50 (72.4%) women. This gives an age-adjusted annual incidence rate of 5.59/10,000 per year in men and 12.4/10,000 per year in women, respectively, for people >50 years of age. Two patients, aged 79 and 82, died 9 and 6 days, respectively, after hospital admission. The average time of hospitalization was 7.5 days (range 4–19 days). As expected, there was a significant rise in hip fractures in people >50 years old. Interestingly, the hip fracture rate in this population is considerably lower (around 4 times less) than the reported rates in white Caucasians.