Riesgo relativo de osteoporosis según la densidad mineral ósea en mujeres menopáusicas sanas de la región occidental de Cuba

Introduction

The highest specificity in the measurement of the magnitude of relative risk of osteoporosis and bone fracture among women is obtained when autochthonous ranges of bone mineral density (BMD), obtained from a normal population, are taken as reference values. These ranges are not sufficiently well established in Latin America.

Objectives

To characterize changes in bone mass according to absorptiometry measurements and the relative risk of osteoporosis in a selected female population (healthy, working women aged more than 49 years old) using BMD risk margins in an autochthonous population as reference values.

Materials and methods

We performed a cross-sectional survey in the western region of Cuba in 307 healthy women, aged 50 to 59 years old, from 1998 to 2007. BMD was measured with a dual-energy X-ray absorptiometry densitometer (DEXA Lunar) in the lumbar spine (anterior-posterior), femoral neck, Ward triangle, trochanter and whole body. Bone density (g/cm²) was obtained and was also expressed as a quotient according to height for each skeletal site (g/m). The percent decrease in bone mass and the frequency of women at relative risk of fracture were calculated. Distributions in percentiles were determined and means and standard deviation were calculated according to ethnic origin. Differences in BMD according to length of amenorrhea, ethnic origin, quotients according to height, and results taking the World Health Organization criteria as reference (safety margins ≤1 standard deviation and risk ≤ 2.5 standard deviation) were evaluated in a young Cuban population and in other reference populations by means of analysis of variance (ANOVA) and Student’s t test for independent samples. Data were processed by SPSS, version 11.5 for Windows.

Results

In the average woman with less than 5 years of amenorrhea, the femur / height quotient, showed a decrease of 7.7 % when compared with peak bone mass in the young population. The frequency of women at risk of fracture increased for fractures of the lumbar spine and femoral neck when the Cuban population was used as reference. According to the risk margin (g/cm²), in the population aged between 50 and 59 years, not differentiated by ethnic origin, the relative risk of fracture of the femoral neck was 4.4 %, that for fracture of the lumbar vertebra was 8.1 % and that for whole-body fracture was 7.7 %. When the Cuban reference was applied for whole body fracture, the presence of risks was similar to the DEXA Lunar criteria.

Conclusions

The prevalence of risk of osteoporosis and decline in bone mass were determined in the study group. Our results provide further evidence of the highest specificity in skeletal sites when measurements are adjusted by height, using the criteria of risk margins in the autochthonous population as a reference.