Low bone mineral density and pain impact in adults with sickle cell disease

Low bone mineral density (BMD) is a prevalent skeletal finding in sickle cell disease (SCD), but its clinical consequences are poorly understood. We hypothesized that low BMD, independent of osteonecrosis (ON), would associate with pain in adults with SCD. In the SCD Bone Pain study, 53 ambulatory adults (64% females; mean age, 38 ± 11 years; 66% hemoglobin [Hb] SS/Sβ0 thalassemia) underwent dual-energy X-ray absorptiometry scans of their lumbar spine, hip, forearm, and whole body. They also completed the Adult Sickle Cell Quality of Life Measurement Information System pain impact questionnaire. Twenty-three participants (43%) had low BMD, defined as lumbar spine, total hip, or femoral neck BMD z scores of -2 or less. In multivariate linear regression, lumbar spine BMD z scores significantly changed by +0.31, -0.29, -0.14, and -1.3 for every unit increase in Hb, indirect bilirubin, and white blood cell count, and with crizanlizumab use, respectively. Pain impact T-scores significantly decreased (worsened) by 6.0 and 6.5 with reduced estimated glomerular filtration rate and chronic opioid therapy but increased (improved) by 3.8 for every unit increase in serum phosphate. The median [interquartile range] pain impact T-scores were significantly lower in participants with low BMD and ON (38.3 [37.4, 40.1]) than those with either low BMD (49.5 [43.6, 54.4]; P = 3 × 10-5) or ON (52.7 [45.3, 57]; P = 2 × 10-4) alone. Whether sickle cell-related low BMD results from impaired bone formation and/or accelerated bone loss remains unclear. Understanding how low bone density, with or without ON, mediates SCD pain warrants further investigation. This trial was registered at www.clinicaltrials.gov as #NCT05283148.