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Nonprogression of Vertebral Area or Bone Mineral Content on DXA Does Not Predict Compression Fractures
Journal of Clinical Densitometry, vol. 9, no. 3, 261e264, 2006 Ó Copyright 2006 by The International Society for Clinical Densitometry 1094-6950/06/9:261e264/$32.00 DOI: 10.1016/j.jocd.2006.05.011
Original Article
Nonprogression of Vertebral Area or Bone Mineral Content on DXA Does Not Predict Compression Fractures Sarah L. Morgan,*,1 Robert Lopez-Ben,1 Nancy Nunnally,2 Leandria Burroughs,2 and Renee Desmond3 1
2
Osteoporosis Prevention and Treatment Clinic, The University of Alabama at Birmingham; The Kirklin Clinic, The University of Alabama at Birmingham Osteoporosis Prevention and Treatment Clinic; and 3The University of Alabama at Birmingham Comprehensive Cancer Center, Birmingham, AL
Abstract The 2003 International Society for Clinical Densitometry consensus guidelines recommend exclusion of vertebral bodies for lack of increase in bone area (BA) or bone mineral content (BMC), or an unusual T-score discrepancy (O1 standard deviation [SD]) between adjacent vertebrae. It is unclear how often nonprogression in BA, BMC, and T-score discrepancies predicts abnormal vertebral morphology, such as compression fractures. We prospectively studied 101 individuals sent for clinical dual-energy X-ray absorptiometry (DXA) scanning, including 20.8% males and 79.2% females. The population was 85% Caucasian, 13% African-American, and 3% Hispanic. The mean age was 65.6 yr; 20.2% were currently on steroids and 22.7% were taking drugs for osteoporosis. All subjects underwent the usual posteroanterior (PA) spine DXA scan PA and lateral vertebral fracture analysis (VFA). The presence of vertebral compression fractures and/or scoliosis of the lumbar spine by VFA were correlated with nonprogression of area or BMC, and/or a difference of O1 SD in T-scores using Fisher’s exact test. By VFA, we detected 22 lumbar compression fractures among 101 subjects, which was 16% of the population. Nonprogression of BA, BMC, and T-score discrepancy were not statistically associated with the presence of vertebral compression fracture as assessed by VFA. Thirty percent of subjects had lumbar spine scoliosis. The presence of scoliosis was significantly related to a T-score discrepancy at L1eL4. Key Words: Bone densitometry; nonprogression; vertebral compression fracture; vertebral fracture analysis.
standard deviation (SD) of adjacent vertebrae’’ (1,2). Peel et al. (3) have published average increases in bone area (BA), and bone mineral content (BMC) from L1eL2, L2eL3, and L3eL4. It is unclear how often nonprogression in BA, BMC, and differences of 1 SD in T-score between lumbar vertebral bodies (T-score discrepancy) are predictive of abnormal vertebral morphology, such as compression fractures. We hypothesized that nonprogression in BA and BMC from L1eL4 would be associated with vertebral compression fractures, as documented by vertebral fracture analysis (VFA). If a lack of increase in BA or BMC were associated with compression fracture in the absence of visible focal structural defects, then further decision algorithms could assist in determining which of the two adjacent vertebra to exclude. Such algorithms could potentially improve interobserver reproducibility and therefore, uniform DXA interpretation among readers.
Introduction The 2003 International Society for Clinical Densitometry (ISCD) consensus guidelines for dual-energy X-ray absorptiometry (DXA) interpretation have recommended the exclusion of vertebral bodies from analysis when the following conditions apply: (1) ‘‘Evidence of a focal structural abnormality; (2) unusual discrepancy in bone mineral content (BMC) or area between adjacent vertebrae. Both measures should increase from L1 to L4; and (3) Individual T-scores should be within 1 Received 02/14/06; Revised 04/13/06; Accepted 05/25/06. *Address correspondence to: Sarah L. Morgan, MD, MS, RD, FADA, FACP, CCD, 354A Learning Resources Center, 1714 9th Avenue South, The University of Alabama at Birmingham, Birmingham, AL 35294-1270. E-mail: [email protected]
261
262
Materials and Methods This project received approval from the University of Alabama at Birmingham Institutional Review Board. Patients undergoing bone densitometry within the Kirklin Clinic at the University of Alabama at Birmingham were asked to participate if they had either a nonprogressive increase in BA or BMC from L1 to L4. The definition of a nonprogressive increase was a nonarithmetic increase in BA or BMC from L1 to L4. After giving informed consent, the patients underwent a posteroanterior (PA) and lateral VFA on a Hologic Discovery W No. 80392 with software version 12.1.7 or a Hologic Discovery A No. 45197 using software version 12.1.3 (Hologic, Bedford, MA). The VFAs were jointly interpreted by Drs. Lopez and Morgan, with consensus agreement for the presence or absence of compression fractures. Computer-assisted diagnosis with 6point vertebral morphometry was performed to quantitate the type and extent of the lumbar compression fractures. The presence of scoliosis was determined using the method of Cobb in the PA VFA image when 10 degrees of lateral spine curvature associated with vertebral rotation was present (Fig. 1) (4). The presence of vertebral compression fractures and/or scoliosis of the spine by VFA were correlated with lack
Fig. 1. Dual-energy X-ray absorptiometry (DXA) of the lumbar spine showing degenerative type lumbar scoliosis with curve centered at L1eL2. The presence of scoliosis was significantly related to a greater than 1 standard deviation (SD) difference in T-score between levels. Journal of Clinical Densitometry
Morgan et al. Table 1 Characteristics of the Study Population Characteristic Ethnicity Caucasian African American Hispanic Gender Males Females Postmenopausal Hysterectomy or oophorectomy Currently on female hormones (estrogen) Currently on oral steroids Ever had a previously diagnosed fracture as an adult Spine Forearm Hip Other Previous surgery on lower back Previous vertebroplasty or kyphoplasty Current osteoporosis medications Alendronate Risedronate Nasal calcitonin Raloxifene Teriparatide Pamidronate Ibandronate Hyperparathyroidism Other comorbidity Bone marrow transplant Renal transplant Heart or lung transplant Asthma Lupus erythematosus Rheumatoid arthritis Cystic fibrosis Eating disorder Scoliosis Scoliosis curve centered at T12eL1 L1eL2 L3eL4 L5eS1
N (%) 85 (85.0) 13 (13.0) 3 (3.0) 21 80 76 24 16 20 51
(20.8) (79.2) (93.8) (32.4) (19.5) (20.2) (50.5)
7 11 5 28 3 1
(7) (11) (5) (28) (3.0) (1.0)
23 8 1 5 5 0 0 1
(22.7) (9.5) (1.2) (6.0) (6.0) (0.0) (0.0) (1.0)
0 3 1 8 3 12 0 0 29
(0.0) (3.0) (1.0) (8.0) (3.0) (12.0) (0.0) (0.0) (28.7)
4 8 11 6
(13.8) (27.6) (37.9) (20.7)
of increase in BA or BMC, and/or a discrepancy in T-score (O1 SD) between adjacent vertebrae. Descriptive statistics were used to evaluate the demographics of the study population. The relationship between the presence of vertebral compression fractures and/or scoliosis of the lumbar spine by VFA and the lack of increase in BA or BMC was evaluated by Fisher’s exact test. The unusual Volume 9, 2006
Does Nonprogression Predict Fracture?
263
Table 2 Relationship Between Nonprogression in BA, BMC T-score Discrepancy, and Scoliosisa BA progression N (%)a
BA nonprogression N (%)
BMC progression N (%)
BMC nonprogression N (%)
T-score discrepancy N (%)
N (%)
Fracture No fracture
5 (31.3)a 34 (40.0)a
11 (68.7)a 51 (60.0)a
5 (31.3) 14 (16.5)
11 (68.7) 71 (83.5)
13 (81.3) 63 (74.1)
3 (18.7) 22 (25.9)
Scoliosis No scoliosis
11 (37.9) 28 (38.9)
p 5 0.75 17 (58.6) 59 (81.9)
12 (41.4) 13 (18.1)
p 5 0.58 18 (62.1) 44 (61.1)
p 5 0.17 8 (27.6) 21 (72.4) 11(15.3) 61 (84.7)
p 5 1.0
p 5 0.17
p 5 0.02
Abbr: BA, bone area; BMC, bone mineral content. a By Fisher’s exact test.
discrepancies in the T-scores as previously defined between adjacent vertebrae were also examined by Fisher’s exact test. For all analyses, a p value of !0.05 (2-sided) was deemed statistically significant.
Results A total of 109 subjects were screened for the trial. One patient declined to participate and 7 subjects were excluded because of the presence of artifacts, hardware, or if they did not fit the inclusion criteria by not having nonprogression in the area of BMC. Table 1 shows the demographics of the study population (n 5 101). The population was predominantly female and Caucasian, with a mean age of 65.6 12.4 yr (SD) and a mean body mass index of 27.5 5.8 yr (SD). More than 20% of the subjects were on oral steroids, 22.7% were being treated with drugs for osteoporosis, and 19.5% were being treated with oral estrogen therapy. There were 35 vertebral compression fractures among 19 different patients identified by VFA in the thoracic and lumbar spine (19%). Twenty-two of these fractures affected the L1eL4 vertebral bodies in 16 different subjects (16%). Table 2 shows the absence of relationship between nonprogression in BA and BMC and the presence or absence of a fracture. We also evaluated whether the site of nonprogression in BA or BMC corresponded to the site of lumbar fracture. When we stratified our data for site specific fractures, the numbers of fractures are too small for meaningful data analysis. The L1 fractures were more frequent than at other sites, where patterns of nonprogression are not available for help in diagnosis. If only grade 2 or 3 fractures were considered, there was no significant relationship with nonprogression of BA ( p 5 0.36) or BMC ( p 5 0.26). Table 2 also shows the relationship between the presence of scoliosis and nonprogression of BA or BMC, or T-score discrepancy between adjacent vertebrae. Lumbar scoliosis was present in 28.7% of our population. The midpoint of the scoliotic curve was at T12eL1 in 13.8%, L1eL2 in Journal of Clinical Densitometry
27.6%, L3eL4 in 37.9%, and at L4eL5 in 20.7% of the population, respectively. The presence of scoliosis was related to a T-score discrepancy between vertebral levels. Figure 1 illustrates scoliosis of the lumbar spine in a PA DXA scan. When subjects with scoliosis were omitted from analysis (n 5 29), nonprogression of BA or BMC was still not predictive of compression fracture.
Discussion We hypothesized that nonprogression in BA or BMC or Tscore discrepancies would be predictive of lumbar vertebral compression fractures on the PA DXA scan. Our data show that nonprogression of BA or BMC or T-score discrepancies are not sensitive predictors of VFA detected lumbar spine fractures. Likewise, the magnitude of the difference in BA or BMC did not predict the presence of compression fracture. Hansen et al. (5) found that the interobserver reproducibility of the ISCD vertebral body exclusion criteria among readers interpreting 200 lumbar DXA scans was only moderate. It was suggested that the choice of excluding either the upper or lower vertebral body when there was nonprogression or a T-score discrepancy may have been one of the causes of the moderate agreement among interpreters. The presence of scoliosis was significantly related to vertebral body T-score discrepancies ( p 5 0.02). Although we did not specifically quantitate the presence of degenerative disc disease, it is likely that degenerative changes such as joint-space narrowing, vertebral endplate sclerosis, and osteophytes were responsible for most of the lack of increase in area and BMC between levels, as most lumbar scoliosis in this age group is secondary to degenerative disc disease (Fig. 1). We acknowledge that grade 1 vertebral fractures are difficult to diagnose using VFA. In addition, a weakness of our study may be that with only 101 subjects, we may not have had the power to detect a relationship between increase in BA and BMC and unusual discrepancy in T-scores (O1 SD) between adjacent vertebrae and compression fractures. Volume 9, 2006
264 Nineteen percent of our population had vertebral fractures by VFA. Schousboe et al. (6) found 27.4% of 342 patients referred for bone densitometry to have compression fractures by lateral vertebral imaging. It is likely that we identified a smaller percentage of referred patients who had vertebral compression fractures, because we did not take a random sample of all patients referred for DXA scanning and 20% of our sample was men. The lack of predictive value and interobserver reproducibility of the guidelines suggests that these guidelines need to be reconsidered, and indeed, the 2005 ISCD official positions omitted progression of BA and BMC as criteria for exclusion of vertebral bodies (7). AVFA is a much more sensitive way to evaluate for the presence of a compression fracture (8e10) than relying on vertebral BA and BMC trends on the PA DXA scan. Computer-aided densitometry software is now available to assist in vertebral body exclusion based on T-score discrepancies (11). In addition, studies should be directed toward creating decision algorithms for omission of vertebral bodies and recognition of DXA findings that predict vertebral fractures as confirmed by VFA or lumbar spine radiographs.
Morgan et al.
2.
3. 4. 5. 6.
7.
8.
Acknowledgment
9.
This project was supported by a 2005 International Society for Clinical Densitometry Special Projects Grant. 10.
References 1. Hamdy RC, Petak SM, Lenchik L. 2002 Which central dual X-ray absorptiometry skeletal sites and regions of interest should
Journal of Clinical Densitometry
11.
be used to determine the diagnosis of osteoporosis? J Clin Densitom 5:S11eS17. Lenchik L, Leib ES, Hamdy RC, Binkley NC, Miller PD, Watts NB. 2002 Executive Summary: International Society for Clinical Densitometry Position Development Conference. J Clin Densitom 5:S1eS3. Peel NFA, Johnson A, Barrington NA, Smith TWD, Eastell R. 1993 Impact of anomalous vertebral segmentation of measurements of bone mineral density. J Bone Miner Res 8:719e723. Morrissy RT, Goldsmith GS, Hall EC, Kehl D, Cowie GH. 1990 Measurement of the Cobb angle on radiographs of patients who have scoliosis. J Bone Joint Surg (Am) 72:320e327. Hansen KE, Binkley N, Christian R, et al. 2005 Interobserver reproducibility of criteria for vertebral body exclusion. J Bone Miner Res 20:501e508. Schousboe JT, DeBold CR, Bowles C, Glickstein S, Rubio RK. 2002 Prevalence of vertebral compression fracture deformity by X-ray absorptiometry of lateral thoracic and lumbar spines in a population referred for bone densitometry. J Clin Densitom 5:239e246. Binkley N, Bilezikian JP, Kendler DL, Leib ES, Lewieck EM, Petak SM. 2006 Official Positions of the International Society for Clinical Densitometry and executive summary of the 2005 position development conference. J Clin Densitom 9:4e14. Genant HK, Li J, Wu CY, Shepherd JA. 2000 Vertebral fractures in osteoporosis. J Clin Densitom 3:281e290. Greenspan SL, von Stetten E, Emond SK, Jones L, Parker RA. 2001 Instant vertebral assessment: a noninvasive dual X-ray absorptiometry technique to avoid misclassification and clinical mismanagement of osteoporosis. J Clin Densitom 4:373e380. Jacobs-Kosmin D, Sandorfi N, Murray H, Abruzzo JL. 2005 Vertebral deformities identified by vertebral fracture assessment. J Clin Densitom 8:267e272. Barden HS, Markwardt P, Payne R, Hawkins B, Frank M, Faulkner KG. 2003 Automated assessment of exclusion criteria for DXA lumbar spine scans. J Clin Densitom 6:401e409.
Volume 9, 2006
Original Article
Nonprogression of Vertebral Area or Bone Mineral Content on DXA Does Not Predict Compression Fractures Sarah L. Morgan,*,1 Robert Lopez-Ben,1 Nancy Nunnally,2 Leandria Burroughs,2 and Renee Desmond3 1
2
Osteoporosis Prevention and Treatment Clinic, The University of Alabama at Birmingham; The Kirklin Clinic, The University of Alabama at Birmingham Osteoporosis Prevention and Treatment Clinic; and 3The University of Alabama at Birmingham Comprehensive Cancer Center, Birmingham, AL
Abstract The 2003 International Society for Clinical Densitometry consensus guidelines recommend exclusion of vertebral bodies for lack of increase in bone area (BA) or bone mineral content (BMC), or an unusual T-score discrepancy (O1 standard deviation [SD]) between adjacent vertebrae. It is unclear how often nonprogression in BA, BMC, and T-score discrepancies predicts abnormal vertebral morphology, such as compression fractures. We prospectively studied 101 individuals sent for clinical dual-energy X-ray absorptiometry (DXA) scanning, including 20.8% males and 79.2% females. The population was 85% Caucasian, 13% African-American, and 3% Hispanic. The mean age was 65.6 yr; 20.2% were currently on steroids and 22.7% were taking drugs for osteoporosis. All subjects underwent the usual posteroanterior (PA) spine DXA scan PA and lateral vertebral fracture analysis (VFA). The presence of vertebral compression fractures and/or scoliosis of the lumbar spine by VFA were correlated with nonprogression of area or BMC, and/or a difference of O1 SD in T-scores using Fisher’s exact test. By VFA, we detected 22 lumbar compression fractures among 101 subjects, which was 16% of the population. Nonprogression of BA, BMC, and T-score discrepancy were not statistically associated with the presence of vertebral compression fracture as assessed by VFA. Thirty percent of subjects had lumbar spine scoliosis. The presence of scoliosis was significantly related to a T-score discrepancy at L1eL4. Key Words: Bone densitometry; nonprogression; vertebral compression fracture; vertebral fracture analysis.
standard deviation (SD) of adjacent vertebrae’’ (1,2). Peel et al. (3) have published average increases in bone area (BA), and bone mineral content (BMC) from L1eL2, L2eL3, and L3eL4. It is unclear how often nonprogression in BA, BMC, and differences of 1 SD in T-score between lumbar vertebral bodies (T-score discrepancy) are predictive of abnormal vertebral morphology, such as compression fractures. We hypothesized that nonprogression in BA and BMC from L1eL4 would be associated with vertebral compression fractures, as documented by vertebral fracture analysis (VFA). If a lack of increase in BA or BMC were associated with compression fracture in the absence of visible focal structural defects, then further decision algorithms could assist in determining which of the two adjacent vertebra to exclude. Such algorithms could potentially improve interobserver reproducibility and therefore, uniform DXA interpretation among readers.
Introduction The 2003 International Society for Clinical Densitometry (ISCD) consensus guidelines for dual-energy X-ray absorptiometry (DXA) interpretation have recommended the exclusion of vertebral bodies from analysis when the following conditions apply: (1) ‘‘Evidence of a focal structural abnormality; (2) unusual discrepancy in bone mineral content (BMC) or area between adjacent vertebrae. Both measures should increase from L1 to L4; and (3) Individual T-scores should be within 1 Received 02/14/06; Revised 04/13/06; Accepted 05/25/06. *Address correspondence to: Sarah L. Morgan, MD, MS, RD, FADA, FACP, CCD, 354A Learning Resources Center, 1714 9th Avenue South, The University of Alabama at Birmingham, Birmingham, AL 35294-1270. E-mail: [email protected]
261
262
Materials and Methods This project received approval from the University of Alabama at Birmingham Institutional Review Board. Patients undergoing bone densitometry within the Kirklin Clinic at the University of Alabama at Birmingham were asked to participate if they had either a nonprogressive increase in BA or BMC from L1 to L4. The definition of a nonprogressive increase was a nonarithmetic increase in BA or BMC from L1 to L4. After giving informed consent, the patients underwent a posteroanterior (PA) and lateral VFA on a Hologic Discovery W No. 80392 with software version 12.1.7 or a Hologic Discovery A No. 45197 using software version 12.1.3 (Hologic, Bedford, MA). The VFAs were jointly interpreted by Drs. Lopez and Morgan, with consensus agreement for the presence or absence of compression fractures. Computer-assisted diagnosis with 6point vertebral morphometry was performed to quantitate the type and extent of the lumbar compression fractures. The presence of scoliosis was determined using the method of Cobb in the PA VFA image when 10 degrees of lateral spine curvature associated with vertebral rotation was present (Fig. 1) (4). The presence of vertebral compression fractures and/or scoliosis of the spine by VFA were correlated with lack
Fig. 1. Dual-energy X-ray absorptiometry (DXA) of the lumbar spine showing degenerative type lumbar scoliosis with curve centered at L1eL2. The presence of scoliosis was significantly related to a greater than 1 standard deviation (SD) difference in T-score between levels. Journal of Clinical Densitometry
Morgan et al. Table 1 Characteristics of the Study Population Characteristic Ethnicity Caucasian African American Hispanic Gender Males Females Postmenopausal Hysterectomy or oophorectomy Currently on female hormones (estrogen) Currently on oral steroids Ever had a previously diagnosed fracture as an adult Spine Forearm Hip Other Previous surgery on lower back Previous vertebroplasty or kyphoplasty Current osteoporosis medications Alendronate Risedronate Nasal calcitonin Raloxifene Teriparatide Pamidronate Ibandronate Hyperparathyroidism Other comorbidity Bone marrow transplant Renal transplant Heart or lung transplant Asthma Lupus erythematosus Rheumatoid arthritis Cystic fibrosis Eating disorder Scoliosis Scoliosis curve centered at T12eL1 L1eL2 L3eL4 L5eS1
N (%) 85 (85.0) 13 (13.0) 3 (3.0) 21 80 76 24 16 20 51
(20.8) (79.2) (93.8) (32.4) (19.5) (20.2) (50.5)
7 11 5 28 3 1
(7) (11) (5) (28) (3.0) (1.0)
23 8 1 5 5 0 0 1
(22.7) (9.5) (1.2) (6.0) (6.0) (0.0) (0.0) (1.0)
0 3 1 8 3 12 0 0 29
(0.0) (3.0) (1.0) (8.0) (3.0) (12.0) (0.0) (0.0) (28.7)
4 8 11 6
(13.8) (27.6) (37.9) (20.7)
of increase in BA or BMC, and/or a discrepancy in T-score (O1 SD) between adjacent vertebrae. Descriptive statistics were used to evaluate the demographics of the study population. The relationship between the presence of vertebral compression fractures and/or scoliosis of the lumbar spine by VFA and the lack of increase in BA or BMC was evaluated by Fisher’s exact test. The unusual Volume 9, 2006
Does Nonprogression Predict Fracture?
263
Table 2 Relationship Between Nonprogression in BA, BMC T-score Discrepancy, and Scoliosisa BA progression N (%)a
BA nonprogression N (%)
BMC progression N (%)
BMC nonprogression N (%)
T-score discrepancy N (%)
N (%)
Fracture No fracture
5 (31.3)a 34 (40.0)a
11 (68.7)a 51 (60.0)a
5 (31.3) 14 (16.5)
11 (68.7) 71 (83.5)
13 (81.3) 63 (74.1)
3 (18.7) 22 (25.9)
Scoliosis No scoliosis
11 (37.9) 28 (38.9)
p 5 0.75 17 (58.6) 59 (81.9)
12 (41.4) 13 (18.1)
p 5 0.58 18 (62.1) 44 (61.1)
p 5 0.17 8 (27.6) 21 (72.4) 11(15.3) 61 (84.7)
p 5 1.0
p 5 0.17
p 5 0.02
Abbr: BA, bone area; BMC, bone mineral content. a By Fisher’s exact test.
discrepancies in the T-scores as previously defined between adjacent vertebrae were also examined by Fisher’s exact test. For all analyses, a p value of !0.05 (2-sided) was deemed statistically significant.
Results A total of 109 subjects were screened for the trial. One patient declined to participate and 7 subjects were excluded because of the presence of artifacts, hardware, or if they did not fit the inclusion criteria by not having nonprogression in the area of BMC. Table 1 shows the demographics of the study population (n 5 101). The population was predominantly female and Caucasian, with a mean age of 65.6 12.4 yr (SD) and a mean body mass index of 27.5 5.8 yr (SD). More than 20% of the subjects were on oral steroids, 22.7% were being treated with drugs for osteoporosis, and 19.5% were being treated with oral estrogen therapy. There were 35 vertebral compression fractures among 19 different patients identified by VFA in the thoracic and lumbar spine (19%). Twenty-two of these fractures affected the L1eL4 vertebral bodies in 16 different subjects (16%). Table 2 shows the absence of relationship between nonprogression in BA and BMC and the presence or absence of a fracture. We also evaluated whether the site of nonprogression in BA or BMC corresponded to the site of lumbar fracture. When we stratified our data for site specific fractures, the numbers of fractures are too small for meaningful data analysis. The L1 fractures were more frequent than at other sites, where patterns of nonprogression are not available for help in diagnosis. If only grade 2 or 3 fractures were considered, there was no significant relationship with nonprogression of BA ( p 5 0.36) or BMC ( p 5 0.26). Table 2 also shows the relationship between the presence of scoliosis and nonprogression of BA or BMC, or T-score discrepancy between adjacent vertebrae. Lumbar scoliosis was present in 28.7% of our population. The midpoint of the scoliotic curve was at T12eL1 in 13.8%, L1eL2 in Journal of Clinical Densitometry
27.6%, L3eL4 in 37.9%, and at L4eL5 in 20.7% of the population, respectively. The presence of scoliosis was related to a T-score discrepancy between vertebral levels. Figure 1 illustrates scoliosis of the lumbar spine in a PA DXA scan. When subjects with scoliosis were omitted from analysis (n 5 29), nonprogression of BA or BMC was still not predictive of compression fracture.
Discussion We hypothesized that nonprogression in BA or BMC or Tscore discrepancies would be predictive of lumbar vertebral compression fractures on the PA DXA scan. Our data show that nonprogression of BA or BMC or T-score discrepancies are not sensitive predictors of VFA detected lumbar spine fractures. Likewise, the magnitude of the difference in BA or BMC did not predict the presence of compression fracture. Hansen et al. (5) found that the interobserver reproducibility of the ISCD vertebral body exclusion criteria among readers interpreting 200 lumbar DXA scans was only moderate. It was suggested that the choice of excluding either the upper or lower vertebral body when there was nonprogression or a T-score discrepancy may have been one of the causes of the moderate agreement among interpreters. The presence of scoliosis was significantly related to vertebral body T-score discrepancies ( p 5 0.02). Although we did not specifically quantitate the presence of degenerative disc disease, it is likely that degenerative changes such as joint-space narrowing, vertebral endplate sclerosis, and osteophytes were responsible for most of the lack of increase in area and BMC between levels, as most lumbar scoliosis in this age group is secondary to degenerative disc disease (Fig. 1). We acknowledge that grade 1 vertebral fractures are difficult to diagnose using VFA. In addition, a weakness of our study may be that with only 101 subjects, we may not have had the power to detect a relationship between increase in BA and BMC and unusual discrepancy in T-scores (O1 SD) between adjacent vertebrae and compression fractures. Volume 9, 2006
264 Nineteen percent of our population had vertebral fractures by VFA. Schousboe et al. (6) found 27.4% of 342 patients referred for bone densitometry to have compression fractures by lateral vertebral imaging. It is likely that we identified a smaller percentage of referred patients who had vertebral compression fractures, because we did not take a random sample of all patients referred for DXA scanning and 20% of our sample was men. The lack of predictive value and interobserver reproducibility of the guidelines suggests that these guidelines need to be reconsidered, and indeed, the 2005 ISCD official positions omitted progression of BA and BMC as criteria for exclusion of vertebral bodies (7). AVFA is a much more sensitive way to evaluate for the presence of a compression fracture (8e10) than relying on vertebral BA and BMC trends on the PA DXA scan. Computer-aided densitometry software is now available to assist in vertebral body exclusion based on T-score discrepancies (11). In addition, studies should be directed toward creating decision algorithms for omission of vertebral bodies and recognition of DXA findings that predict vertebral fractures as confirmed by VFA or lumbar spine radiographs.
Morgan et al.
2.
3. 4. 5. 6.
7.
8.
Acknowledgment
9.
This project was supported by a 2005 International Society for Clinical Densitometry Special Projects Grant. 10.
References 1. Hamdy RC, Petak SM, Lenchik L. 2002 Which central dual X-ray absorptiometry skeletal sites and regions of interest should
Journal of Clinical Densitometry
11.
be used to determine the diagnosis of osteoporosis? J Clin Densitom 5:S11eS17. Lenchik L, Leib ES, Hamdy RC, Binkley NC, Miller PD, Watts NB. 2002 Executive Summary: International Society for Clinical Densitometry Position Development Conference. J Clin Densitom 5:S1eS3. Peel NFA, Johnson A, Barrington NA, Smith TWD, Eastell R. 1993 Impact of anomalous vertebral segmentation of measurements of bone mineral density. J Bone Miner Res 8:719e723. Morrissy RT, Goldsmith GS, Hall EC, Kehl D, Cowie GH. 1990 Measurement of the Cobb angle on radiographs of patients who have scoliosis. J Bone Joint Surg (Am) 72:320e327. Hansen KE, Binkley N, Christian R, et al. 2005 Interobserver reproducibility of criteria for vertebral body exclusion. J Bone Miner Res 20:501e508. Schousboe JT, DeBold CR, Bowles C, Glickstein S, Rubio RK. 2002 Prevalence of vertebral compression fracture deformity by X-ray absorptiometry of lateral thoracic and lumbar spines in a population referred for bone densitometry. J Clin Densitom 5:239e246. Binkley N, Bilezikian JP, Kendler DL, Leib ES, Lewieck EM, Petak SM. 2006 Official Positions of the International Society for Clinical Densitometry and executive summary of the 2005 position development conference. J Clin Densitom 9:4e14. Genant HK, Li J, Wu CY, Shepherd JA. 2000 Vertebral fractures in osteoporosis. J Clin Densitom 3:281e290. Greenspan SL, von Stetten E, Emond SK, Jones L, Parker RA. 2001 Instant vertebral assessment: a noninvasive dual X-ray absorptiometry technique to avoid misclassification and clinical mismanagement of osteoporosis. J Clin Densitom 4:373e380. Jacobs-Kosmin D, Sandorfi N, Murray H, Abruzzo JL. 2005 Vertebral deformities identified by vertebral fracture assessment. J Clin Densitom 8:267e272. Barden HS, Markwardt P, Payne R, Hawkins B, Frank M, Faulkner KG. 2003 Automated assessment of exclusion criteria for DXA lumbar spine scans. J Clin Densitom 6:401e409.
Volume 9, 2006