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Muscle Function, But Not Muscle Mass, Is Related to Balance Confidence in Older Adults
502
Abstracts
6.6% vs 5.6% and Garvan with BMD 6.5% vs 3.9%. The total Hip aBMD T score in the in the 68 participants who sustained a hip fracture compared to the 1059 who did not were -1.65 0.97 and -1.04 1.01 (p!0.001). The table below shows the ROC areas under the curve (AUC) and diagnostic measures for each risk model. The Youden index was used to determine the best sensitivity and specificity cut off for each ROC. Conclusions: These data show that neither calculator improves on the hip fracture prediction compared to the model using the total hip or femoral neck T score alone.
144
Risk Assessment and Epidemiology: Osteoporosis and Other Conditions
MUSCLE FUNCTION, BUT NOT MUSCLE MASS, IS RELATED TO BALANCE CONFIDENCE IN OLDER ADULTS Bjoern Buehring, University of Wisconsin-Madison Ellen Fidler, University of Wisconsin; Jessie Libber, University of Wisconsin; Mary Checovich, University of Wisconsin; Diane Krueger, University of Wisconsin; Neil Binkley, University of Wisconsin Background: Both impaired muscle function and low muscle mass are included in recent consensus sarcopenia definitions. Sarcopenia is associated with increased risk of falls and fear of falling. Self-reported health is a falls risk factor that predicts hip fracture. However, how self-reported balance confidence relates to objective measures of muscle function and mass has received only limited evaluation. As such, this study examined the relationship of balance confidence with jumping mechanography (JM) parameters, classical muscle function tests, and appendicular lean mass (ALM) as measured by DXA. Methods: Community dwelling individuals age 70+ completed the Activitiesspecific Balance Confidence (ABC) scale to assess balance confidence. This scale is reliable and able to distinguish fallers from non-fallers. Additionally, all volunteers performed several muscle function tests including the short physical performance battery (SPPB), grip strength, and JM. JM assesses muscle function using countermovement jumps to calculate body weight corrected peak power and jump height. Total body DXA was used to assess ALM. Statistical testing included correlation of ABC scores with muscle function tests and ALM/height2. Based on their ABC score, participants were divided into groups of high, moderate, and low balance confidence. Receiver-Operator Curves (ROC) and their area under curve (AUC) for the three defined confidence groups were calculated for the different muscle parameters. Results: 97 individuals (49 females and 48 males, mean age 80.6, range 70 e 95 years) with and without osteoporosis and sarcopenia were studied. Participants had high balance confidence with only 10 individuals having ABC scores in the moderate range and none in the low range. Correlations from various regression analyses were statistically significant but small and ranged from 0.05 for grip strength to 0.28 for total SPPB score (P-values all !0.05 or lower). ALM/height2 was not associated with ABC score (P50.625). ROC analysis revealed highest AUCs for gait speed and total SPPB score (w0.83). Jump power/height and chair rise time had lower AUCs (w0.75). Conclusions: Tests of muscle function, including JM, but not simple lean mass measurement, are associated with balance confidence. These data support the need to include both measures of muscle mass and muscle ‘‘quality’’ in clinical definitions of sarcopenia. This study is limited by the generally high balance confidence in the study cohort. Further studies are needed to develop a sarcopenia testbattery that is able to identify individuals at high falls risk. Subsequent implementation of such a testing approach may well increase accuracy of fracture estimation.
145
Risk Assessment and Epidemiology: Osteoporosis and Other Conditions
SCREENING OF OSTEOPOROSIS BY DIFFERENT METHODS IN OLD MALES LIVED IN A RURAL COMMUNITY Chih-Hsing Wu, National Cheng Kung University Medical Center Hong-Yu Chen, College of Medicine, National Cheng Kung University; Yin-Fan Chang, National Cheng Kung University Hospital; Chin-Sung Chang, National
Journal of Clinical Densitometry: Assessment of Skeletal Health
Cheng Kung University Hospital; Chuan-Yu Chen, Public Health Center, Tianliao District, Kaohsiung City; Mei-Wen Wang, Tainan Hospital Xinhua Branch, Department of Health; Yi-Ching Yang, National Cheng Kung University Hospital Objectives: Male osteoporosis is not uncommon, but underestimated unintentionally. This study aimed to disclose the influence of different methods on the screening of osteoporosis among elderly males living in a rural community in Taiwan. Methods: In 2010, an epidemiological survey using the whole-community screening method was performed for 1033 elderly males living in Tianliao District, Kaohsiung City in southern Taiwan. A total of 414 subjects (age: 74.6 6.2 y/o, response rate 5 60.8%) completed the structured questionnaires via a face-to-face interview by a well-trained investigator. Lumbar (L1-4) and hip (total and neck) bone mineral density was measured by mobile dual energy X-ray absorptiometry (DXA, Hologic Explorer QDR). Diagnosis of osteoporosis (T-score !5-2.5, young Asian reference) was confirmed by either the 1994 WHO criteria or history of non-traumatic fracture. Thoraco-lumbar X-ray was measured by mobile X-ray (Daeyoung DC-325R). The compression fracture was confirmed as O5 20% reduction of vertebral body height (Genant HK et al. 1993). The 10-year probability of major osteoporotic fracture was assessed by the FRAXÒ algorithms developed by WHO. Results: Of 413 subjects completed questionnaires, 51 (12.3%) mentioned history of osteoporosis, while 18 (4.4%) had history of non-traumatic fracture. Of the 406 subjects scanned by DXA, 70 (17.2%) reached the diagnostic criteria of osteoporosis. Of 401 subjects with thoracolumbar X-ray, 234 (58.4%) were diagnosed with compression fracture. Considering all combinations of four diagnostic criteria above, the prevalence of osteoporosis was ranged from 4.4% up to 70.2% (fig 1)? Using the X-ray as the golden standard of compression fracture, the DXA, FRAX, history of osteoporosis or history of non-traumatic fracture all showed no discriminative ability in ROC curve. Using the DXA as the golden standard of osteoporosis, the cut-off of 10-year hip fracture probability at either 3%, 4%, or 5% had acceptable discriminative ability. Conclusions: In elderly male living in rural community in Taiwan, osteoporosis is not uncommon, and the prevalence of compression fracture is extremely high. As a result, thoracolumbar X-ray should be included to avoid the underestimation of the osteoporotic prevalence. Hip FRAX without bone mass density at 35% cut-offs have high negative predictive value and is appropriate for initial screening of osteoporosis in old males lived in rural community.
146
Risk Assessment and Epidemiology: Osteoporosis and Other Conditions
THE EFFECT OF COMPETING MORTALITY ON FRACTURE RISK ASSESSMENT William Leslie, University of Manitoba Lisa Lix, University of Saskatchewan; Xiaojing Wu, University of Saskatchewan Objective: A unique feature of FRAX is that the estimation of fracture probability accounts for the competing risk of mortality. A standard Kaplan-Meier (KM) method for time-to-event analysis does not adjust for competing mortality. Therefore we compared non-parametric and parametric methods that do and do not account for competing mortality, and propose a new approach based on a modified KM method. Methods: The Manitoba BMD database was used to identify men and women age 5 50y with FRAX probabilities calculated using femoral neck BMD (N 5 39,063). Fractures were assessed from administrative data (N 5 2,543 with a major osteoporotic fracture, N 5 549 with a hip fracture during mean 5.3y follow-up). Results were stratified by variables for which competing mortality is expected to exert a differential effect: sex, age, major osteoporotic fracture probability, and presence of diabetes. In the modified KM method, death before a defining fracture was not censored at the time of death as in standard KM analysis. Instead, this was assigned a final follow up equal to the end of the observation period and a final status of being fracture-free. Censoring only occurred for loss to follow up from migration. Results: There was significantly higher mortality in the subgroups of interest. Estimates of fracture probability that did not consider competing mortality risk were consistently higher than estimates with adjustment for competing mortality risk. Ten-year major osteoporotic fracture probabilities were greater for men than women when no adjustment was made for mortality risk. When estimated with competing mortality, this was reversed with lower 10-year fracture probability in men than women. In the subgroups of interest (men, diabetics, high FRAX probability, age O80y), failure to account for competing mortality overestimated fracture risk by 16-56% with the standard KM method (non-parametric) and 1529% with the Cox model (parametric). Similar findings were seen when the outcome was hip fractures: failure to account for competing mortality overestimated
Volume 15, 2012
Abstracts
6.6% vs 5.6% and Garvan with BMD 6.5% vs 3.9%. The total Hip aBMD T score in the in the 68 participants who sustained a hip fracture compared to the 1059 who did not were -1.65 0.97 and -1.04 1.01 (p!0.001). The table below shows the ROC areas under the curve (AUC) and diagnostic measures for each risk model. The Youden index was used to determine the best sensitivity and specificity cut off for each ROC. Conclusions: These data show that neither calculator improves on the hip fracture prediction compared to the model using the total hip or femoral neck T score alone.
144
Risk Assessment and Epidemiology: Osteoporosis and Other Conditions
MUSCLE FUNCTION, BUT NOT MUSCLE MASS, IS RELATED TO BALANCE CONFIDENCE IN OLDER ADULTS Bjoern Buehring, University of Wisconsin-Madison Ellen Fidler, University of Wisconsin; Jessie Libber, University of Wisconsin; Mary Checovich, University of Wisconsin; Diane Krueger, University of Wisconsin; Neil Binkley, University of Wisconsin Background: Both impaired muscle function and low muscle mass are included in recent consensus sarcopenia definitions. Sarcopenia is associated with increased risk of falls and fear of falling. Self-reported health is a falls risk factor that predicts hip fracture. However, how self-reported balance confidence relates to objective measures of muscle function and mass has received only limited evaluation. As such, this study examined the relationship of balance confidence with jumping mechanography (JM) parameters, classical muscle function tests, and appendicular lean mass (ALM) as measured by DXA. Methods: Community dwelling individuals age 70+ completed the Activitiesspecific Balance Confidence (ABC) scale to assess balance confidence. This scale is reliable and able to distinguish fallers from non-fallers. Additionally, all volunteers performed several muscle function tests including the short physical performance battery (SPPB), grip strength, and JM. JM assesses muscle function using countermovement jumps to calculate body weight corrected peak power and jump height. Total body DXA was used to assess ALM. Statistical testing included correlation of ABC scores with muscle function tests and ALM/height2. Based on their ABC score, participants were divided into groups of high, moderate, and low balance confidence. Receiver-Operator Curves (ROC) and their area under curve (AUC) for the three defined confidence groups were calculated for the different muscle parameters. Results: 97 individuals (49 females and 48 males, mean age 80.6, range 70 e 95 years) with and without osteoporosis and sarcopenia were studied. Participants had high balance confidence with only 10 individuals having ABC scores in the moderate range and none in the low range. Correlations from various regression analyses were statistically significant but small and ranged from 0.05 for grip strength to 0.28 for total SPPB score (P-values all !0.05 or lower). ALM/height2 was not associated with ABC score (P50.625). ROC analysis revealed highest AUCs for gait speed and total SPPB score (w0.83). Jump power/height and chair rise time had lower AUCs (w0.75). Conclusions: Tests of muscle function, including JM, but not simple lean mass measurement, are associated with balance confidence. These data support the need to include both measures of muscle mass and muscle ‘‘quality’’ in clinical definitions of sarcopenia. This study is limited by the generally high balance confidence in the study cohort. Further studies are needed to develop a sarcopenia testbattery that is able to identify individuals at high falls risk. Subsequent implementation of such a testing approach may well increase accuracy of fracture estimation.
145
Risk Assessment and Epidemiology: Osteoporosis and Other Conditions
SCREENING OF OSTEOPOROSIS BY DIFFERENT METHODS IN OLD MALES LIVED IN A RURAL COMMUNITY Chih-Hsing Wu, National Cheng Kung University Medical Center Hong-Yu Chen, College of Medicine, National Cheng Kung University; Yin-Fan Chang, National Cheng Kung University Hospital; Chin-Sung Chang, National
Journal of Clinical Densitometry: Assessment of Skeletal Health
Cheng Kung University Hospital; Chuan-Yu Chen, Public Health Center, Tianliao District, Kaohsiung City; Mei-Wen Wang, Tainan Hospital Xinhua Branch, Department of Health; Yi-Ching Yang, National Cheng Kung University Hospital Objectives: Male osteoporosis is not uncommon, but underestimated unintentionally. This study aimed to disclose the influence of different methods on the screening of osteoporosis among elderly males living in a rural community in Taiwan. Methods: In 2010, an epidemiological survey using the whole-community screening method was performed for 1033 elderly males living in Tianliao District, Kaohsiung City in southern Taiwan. A total of 414 subjects (age: 74.6 6.2 y/o, response rate 5 60.8%) completed the structured questionnaires via a face-to-face interview by a well-trained investigator. Lumbar (L1-4) and hip (total and neck) bone mineral density was measured by mobile dual energy X-ray absorptiometry (DXA, Hologic Explorer QDR). Diagnosis of osteoporosis (T-score !5-2.5, young Asian reference) was confirmed by either the 1994 WHO criteria or history of non-traumatic fracture. Thoraco-lumbar X-ray was measured by mobile X-ray (Daeyoung DC-325R). The compression fracture was confirmed as O5 20% reduction of vertebral body height (Genant HK et al. 1993). The 10-year probability of major osteoporotic fracture was assessed by the FRAXÒ algorithms developed by WHO. Results: Of 413 subjects completed questionnaires, 51 (12.3%) mentioned history of osteoporosis, while 18 (4.4%) had history of non-traumatic fracture. Of the 406 subjects scanned by DXA, 70 (17.2%) reached the diagnostic criteria of osteoporosis. Of 401 subjects with thoracolumbar X-ray, 234 (58.4%) were diagnosed with compression fracture. Considering all combinations of four diagnostic criteria above, the prevalence of osteoporosis was ranged from 4.4% up to 70.2% (fig 1)? Using the X-ray as the golden standard of compression fracture, the DXA, FRAX, history of osteoporosis or history of non-traumatic fracture all showed no discriminative ability in ROC curve. Using the DXA as the golden standard of osteoporosis, the cut-off of 10-year hip fracture probability at either 3%, 4%, or 5% had acceptable discriminative ability. Conclusions: In elderly male living in rural community in Taiwan, osteoporosis is not uncommon, and the prevalence of compression fracture is extremely high. As a result, thoracolumbar X-ray should be included to avoid the underestimation of the osteoporotic prevalence. Hip FRAX without bone mass density at 35% cut-offs have high negative predictive value and is appropriate for initial screening of osteoporosis in old males lived in rural community.
146
Risk Assessment and Epidemiology: Osteoporosis and Other Conditions
THE EFFECT OF COMPETING MORTALITY ON FRACTURE RISK ASSESSMENT William Leslie, University of Manitoba Lisa Lix, University of Saskatchewan; Xiaojing Wu, University of Saskatchewan Objective: A unique feature of FRAX is that the estimation of fracture probability accounts for the competing risk of mortality. A standard Kaplan-Meier (KM) method for time-to-event analysis does not adjust for competing mortality. Therefore we compared non-parametric and parametric methods that do and do not account for competing mortality, and propose a new approach based on a modified KM method. Methods: The Manitoba BMD database was used to identify men and women age 5 50y with FRAX probabilities calculated using femoral neck BMD (N 5 39,063). Fractures were assessed from administrative data (N 5 2,543 with a major osteoporotic fracture, N 5 549 with a hip fracture during mean 5.3y follow-up). Results were stratified by variables for which competing mortality is expected to exert a differential effect: sex, age, major osteoporotic fracture probability, and presence of diabetes. In the modified KM method, death before a defining fracture was not censored at the time of death as in standard KM analysis. Instead, this was assigned a final follow up equal to the end of the observation period and a final status of being fracture-free. Censoring only occurred for loss to follow up from migration. Results: There was significantly higher mortality in the subgroups of interest. Estimates of fracture probability that did not consider competing mortality risk were consistently higher than estimates with adjustment for competing mortality risk. Ten-year major osteoporotic fracture probabilities were greater for men than women when no adjustment was made for mortality risk. When estimated with competing mortality, this was reversed with lower 10-year fracture probability in men than women. In the subgroups of interest (men, diabetics, high FRAX probability, age O80y), failure to account for competing mortality overestimated fracture risk by 16-56% with the standard KM method (non-parametric) and 1529% with the Cox model (parametric). Similar findings were seen when the outcome was hip fractures: failure to account for competing mortality overestimated
Volume 15, 2012