ABSTRACT
<p><b>Objective</b>: Monitoring the incidence of atypical femoral fractures (AFFs) using medical claim databases is useful to assess the safety of long-term bisphosphonate exposure. Therefore, we aimed to validate the relationship between clinically-defined suspected AFFs and the candidate patients obtained from claims data at three hospitals in Japan.</p><p><b>Design</b>: A cross-sectional study involving three hospitals that perform bone fracture surgery and from which electronic medical record databases of diagnoses and procedures are available.</p><p><b>Methods</b>: Candidate patients were at the medical databases using two International Classification of Diseases, 10th Edition (ICD-10) codes (subtrochanteric fracture and fracture of shaft of femur) in the claims databases. These potential cases by claim-based definition were validated using clinically-confirmed information such as, the patient operation records, the discharge records, or radiographic imaging findings as suspected AFFs.</p><p><b>Results</b>: Among fracture cases in the hospitals, and 9 cases with subtrochanteric fracture and 23 cases with femoral shaft fracture were identified based on the ICD-10 codes in the claims databases. Clinically confirmed subtrochanteric fracture had a sensitivity of 81.8% (95% CI: 48.2-97.7%), and a specificity of 100.0% (95% CI: 99.9-100.0%). For femoral shaft fracture, the sensitivity was 82.1% (95% CI: 63.1-93.9%), and the specificity was 100.0% (95% CI: 99.9-100.0%). In subgroup analyses, the sensitivities in patients over the age of 50 years with a single fracture site and with osteoporosis were relatively higher than in other subgroups.</p><p><b>Conclusion</b>: The claims-based definitions of suspected AFFs are accurate, indicating the value of pharmacoepidemiological studies using the National Receipt Database.</p>
ABSTRACT
Underwater weighing is based on the assumption that fat-free body density is roughly constant among humans. This assumption should be examined, because fat-free body density may in fact depend on the bone mineral and water contents of the body, with fat excluded. The purpose of this study was to investigate the effects of bone mineral content (BMC) and density (BMD) on the accuracy of body fat measured underwater. The subjects were 12 young men (25.1±3.7 years, mean ± SD), some of whom were trained athletes. BMC and BMD were measured by dual-energy x-ray absorptiometry (DXA), as was body fat, as a percentage of body weight; this method is not based on the assumption that fat-free body density is the same in different individual. Body fat as a percen tage of body weight was measured underwater, also. Body fat measured by DXA was significantly correlated with that found by underwater weighing (r = 0.83, p<0.01), as expected, but the mean body fat found by DXA was 4.3% higher. The differences between results by the two methods for individuals were from -11.5% to 2.7%, and the differences were negatively correlated with BMC/fat-free weight (FFW ; r=-0.82, p < 0.01) and BMD (r=-0.85, p<0.01) . Fat-free body density ranged from 1.097 to 1.111 g/cm<SUP>3</SUP>because BMC/FFWs varied with the individual. We concluded that individual differences in BMC/FFW and BMD affected the fat-free body density. The variations in fat-free body density would give rise to systematic errors in body composition measured underwater.