Effect of T12 Mislabeling as L1 on the Diagnosis of Low BMD at Lumbar Spine.
J Clin Densitom. 2020 Nov 10;: Authors: Sarathi V, Rakesh CV, Tirupati S
INTRODUCTION: Mislabeling of T12 vertebra as L1 has been shown to reduce L1-L4 bone mineral density (BMD). However, the effect of such mislabeling on the L1-L4 BMD and prevalence of osteoporosis and/or osteopenia in a clinical setting is not known. The study aimed to the effect of mislabelling of T12 as L1 on the L1-L4 BMD and diagnosis of osteoporosis and/or osteopenia. It is a retrospective study done at a tertiary health care center in South India. Database of dual X-ray absorptiometry machine at our center was reviewed and BMD data of men aged more than 50 years and postmenopausal women who underwent BMD during the last 3.5 years were included in the analysis. A total of 570 subjects had undergone BMD testing at the lumbar spine of whom images of the T12 and lower part of the T11 were available for 293 subjects. Six of these with ≤1 eligible vertebra for the calculation of L1-L4 BMD were further excluded from the analysis. The BMD data of the remaining 287 subjects were noted. Later T12 was labeled as L1 and a new set of BMD data was obtained. Using the WHO classification, BMD status was classified as normal BMD, osteopenia, and osteoporosis for both the analyses. L1-L4 BMD (0.916 ± 0.163 vs 0.937 ± 0.170, p < 0.0001) and T-scores of L1-L4 (-2.23 ± 1.37 vs -2.06 ± 1.43, p < 0.0001) with mislabeling were significantly lower than those measured with correct labeling. BMD status was misclassified by T12 mislabelling as L1 in a total of 30 (10.4%) individuals. Inter-rater agreement between the 2 scenarios for the diagnosis of osteoporosis, osteopenia, and normal BMD was substantial (weighted Kappa: 0.87 [95%CI: 0.83-0.91]). To conclude, mislabeling of T12 as L1 significantly reduces L1-L4 BMD. However, the diagnosis of BMD status by mislabeling has a substantial agreement with that obtained with correct labeling. PMID: 33268024 [PubMed - as supplied by publisher]