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Prospective cohort of 50 adults with sickle cell disease (SCD) undergoing research DXA scan to assess bone mineral density and thoracolumbar morphometry for vertebral fracture analysis

Measure bone mineral density at the lumbar spine, left total hip, left forearm, and whole body

• DXA-skannaus

Obtain thoracolumbar morphometry in DXA scan, then determine presence and severity of vertebral compression fractures by VFA

• VFA

Calculate patient-reported total pain scores to determine the pain phenotype of each study participant

• ASCQ-Me Pain -pisteet

Areal bone mineral density of the lumbar spine measured by dual-energy X-ray absorptiometry (DXA) scan and reported in grams per square centimeter.

Number of standard deviations between measured lumbar spine bone mineral density (g/cm2) for each participant and mean lumbar spine bone mineral density (g/cm2) of the reference population. A Z-score of 0 represents the mean of the reference population. A negative Z-score means the measured bone mineral density values are lower (worse) the reference mean, while positive Z-scores mean they are above/higher. Bone mineral density Z-scores ≤ -2 indicates low bone density.

Areal bone mineral density of the total hip measured by dual-energy X-ray absorptiometry (DXA) scan and reported in grams per square centimeter.

Number of standard deviations between measured total hip bone mineral density (g/cm2) for each participant and mean total hip bone mineral density (g/cm2) of the reference population. A Z-score of 0 represents the mean of the reference population. A negative Z-score means the measured bone mineral density values are lower (worse) the reference mean, while positive Z-scores mean they are above/higher. Bone mineral density Z-scores ≤ -2 indicates low bone density.

Areal bone mineral density of the femoral neck measured by dual-energy X-ray absorptiometry (DXA) scan and reported in grams per square centimeter.

Number of standard deviations between measured lumbar spine bone mineral density (g/cm2) for each participant and mean lumbar spine bone mineral density (g/cm2) of the reference population. A Z-score of 0 represents the mean of the reference population. A negative Z-score means the measured bone mineral density values are lower (worse) the reference mean, while positive Z-scores mean they are above/higher. Bone mineral density Z-scores ≤ -2 indicates low bone density.

Patient-reported outcome measure of pain impact in the preceding 7 days before bone density measurements. The Adult Sickle Cell Quality of Life Measurement System (ASCQ-Me) pain impact T-scores range from about 30-100. The ASCQ-Me pain impact T-score has standardized mean T-score of 50 and standard deviation of 10, which were derived from a reference population of ambulatory adult with sickle cell disease across the United States. ASCQ-Me pain impact T-scores less than 50 are lower/worse than the reference mean (more severe pain impact), while pain impact T-scores greater than 50 are above/better than the reference mean (less severe pain impact)

The spinal deformity index (SDI) is a semi-quantitative measure of number and severity of vertebral fractures observed on lateral spine X-rays of the thoracolumbar spine. To calculate the SDI, vertebrae are assigned a score as follows: 0 (no fracture), 1 (mild fracture), 2 (moderate fracture), and 3 (severe fracture). The total SDI is the summation of all T12-L4 vertebrae measured on the lateral spine X-rays. Minimum SDI =0 and Maximum SDI=15. Higher scores mean increased (worse) fracture burden, lower scores mean decreased (less) fracture burden.