Comparison between the Klemetti index and heel DXA BMD measurements in the diagnosis of reduced skeletal bone mineral density in the elderly

Osteopenia/osteoporosis affect many elderly people and might not be detected until symptoms of fractures occur. Early detection of osteopenia/osteoporosis is important and would allow preventive measures and treatment. Access to screening for osteopenia/osteoporosis is often limited, whereas panoramic radiography is commonly used in dentistry. The aim of this study was to determine the validity of the Klemetti index (KI), measured on panoramic radiographs, in the diagnosis of osteopenia/osteoporosis as defined by a bone mineral density (BMD) measurement below) 1.5 standard deviations (SDs) of a community based sample. In total, 211 consecutive participants ( 102 men and 109 women) 60 - 96 years in the SNAC-Blekinge study ( Swedish National Study on Ageing and Care) underwent bone densitometry [ by dual-energy X-ray absorptiometry (DXA)] of both heels. A panoramic radiograph was taken of each participant, and mandibular cortex on a panoramic radiograph was classified as '0' or normal ( even and sharp endosteal margin), '1', moderately eroded ( evidence of lacunar resorption or endosteal cortical residues), or '2', severely eroded ( unequivocal porosity). From logistic regression, the odds ratio of having a BMD measurement below -1.5 SD was 8.04 (95% CI 2.39 to 27.12, P< 0.001) in the 'osteopenic' (KI category 2), compared with the 'normal' group ( KI categories 0 and 1). Receiver operating characteristic (ROC) curve analysis was used to measure the validity of the KI indicating osteopenia ( KI category 2) in predicting reduced BMD. This point provided a sensitivity of 50% and a specificity of 89%. Positive and negative predictive values were 21% and 97%, respectively. There were 87% correctly classified subjects. The area under the ROC curve was 0.64. The present study demonstrated that a negative finding ( KI category < 2) is highly predictive of the absence of osteopenia/osteoporosis as defined by the DXA measurements.