Alendronate preserves bone mineral density in adults with sickle cell disease and osteoporosis

Low bone mineral density is highly prevalent in sickle cell disease (SCD); whether bisphosphonates can safely preserve or increase bone mass in SCD adults remains unknown. In this study, lumbar spine bone density remained stable with alendronate use, and treatment-related side effects were mostly mild and self-limited.

To describe the effects of alendronate in adults with sickle cell disease (SCD) and osteoporosis.

We reviewed retrospective clinical data from adults with SCD and osteoporosis treated with alendronate at a single center in Brazil (2009-2019). Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) of the lumbar spine, femoral neck, and total hip. We analyzed BMD changes by alendronate treatment duration (months), stratified by sex, skeletal site, and SCD genotype.

Sixty-four SCD adults with osteoporosis (69% females, 73% HbSS, mean age ± standard deviation 42.4 ± 10.9 years) received alendronate for a median (interquartile range) of 48 (29, 73) months. Compared with males, females had significantly lower baseline BMD (g/cm²) at the femoral neck (0.72 vs 0.85, p =  < 0.001) and total hip (0.79 vs 0.88, p = 0.009). The between-sex differences in BMD changes were insignificant. Mean lumbar spine BMD significantly changed by 0.0357 g/cm² (p = 0.028) in those on alendronate for > 5 years. Four adults (6.3%) reported mild therapy-related side effects. An atypical femoral diaphysis fracture, attributed to alendronate, was incidentally noted in a 37-year-old man on treatment for 4 years.

In this retrospective cohort of adults with SCD and osteoporosis on alendronate for a median of 48 months, we found no significant interactions between sex and changes in lumbar spine, femoral neck, or total hip BMD with alendronate. Lumbar spine BMD was stable in those on alendronate for < 5 years. Side effects of alendronate were mild, though one patient developed an atypical femoral fracture.