Bone mineral density of the spine and femur in a group of healthy Moroccan men

Abstract

Background: Bone mineral density (BMD) measurements using dual-energy X-rays absorptiometry (DXA) are widely used to diagnose osteoporosis and to assess its severity. Previous studies show the necessity to establish reference data for bone mass measurements for each particular population. Such data are lacking for the male Moroccan population.

Aim: To establish reference values for the healthy Moroccan male population and to compare them with those for Caucasian and Arab males, and to study the impact of different curves implemented in the DXA system on the diagnosis of osteoporosis.

Methods: A cross-sectional study of 592 Moroccan men, recruited from the area of Rabat, the capital of Morocco, aged between 20 and 79 years was carried to establish reference values of bone mineral density. Measurements were taken at the lumbar spine and proximal femurs using DXA (Lunar Prodigy Vision, GE). The data were compared with published normative taken by US, European, Iranian, Lebanese, and Saudi men over six decades of age. Impact on osteoporosis diagnosis according to the WHO criteria using the personalized curve and US (NHANES), European and Middle-East reference curves (as implemented in the Lunar densitometers) was studied.

Results: Our results showed that the Moroccan men showed the expected decline in BMD at both sites with age after peaking at 20-29 years age group. Every anatomical region has a different rate of bone loss: lumbar spine (0.3% per year) femoral neck (0.6%), trochanter (0.3%), and total hip (0.4%). The lumbar spine and femoral subregions BMD exhibited increases from 0.3 to 0.5% per kilogram of body weight. In the spine, the US/European Lunar reference values classified a larger proportion of men as osteoporotic (18.1% vs. 7.4%) while using the Arabic Lunar reference values, only 7.8% were classified as osteoporotic. However, using Arabic curve for the femurs resulted in underdiagnosis of osteoporosis (1.8% vs. 6.0%), whereas the US/European Lunar reference values classified men as osteoporotic in 3.9% and 5.3% respectively.

Discussion: In comparison with the other Countries, the spine BMD of Moroccan men were slightly lower than Iranian's, Europeans and Brazilians but higher than the Saudi and Lebanese males. We found BMD values taken at the lumbar spine to be around 4% lower than European values between ages 50 and 59 years, and 10% lower for older subjects. These values were 4-6% higher than Saudis/Lebanese values between ages 20-39. For older subjects, Moroccan values were more than 10% higher than Saudis and almost similar to Lebanese. Femoral neck BMD values were 8% higher in young adults (age 20-39 years) to US/Saudis/Lebanese values, but about 10% lower in ages over 60 to US values whereas it was similar to Saudis and Lebanese values.

Conclusion: Our study emphasises the importance of using population-specific reference values for BMD measurements to avoid over or underdiagnosis of osteoporosis.