|LETTER TO EDITOR
|Ahead of print publication
Bone mineral density is decreased in patients with systemic sclerosis and correlates with serum intact parathormone levels: A cross-sectional study
Mahmood Dhahir Al-Mendalawi
Department of Paediatrics, Al-Kindy College of Medicine, University of Baghdad, Baghdad, Iraq
Mahmood Dhahir Al-Mendalawi,
P.O. Box 55302, Baghdad Post Office, Baghdad
Source of Support: None, Conflict of Interest: None
|How to cite this URL:|
Al-Mendalawi MD. Bone mineral density is decreased in patients with systemic sclerosis and correlates with serum intact parathormone levels: A cross-sectional study. Indian J Rheumatol [Epub ahead of print] [cited 2019 Nov 20]. Available from: http://www.indianjrheumatol.com/preprintarticle.asp?id=264872
I refer to the distinguished study by Sharma et al. published in June 2019 issue of the Indian Journal of Rheumatology. The authors revealed bone mineral density (BMD) in Indian patients with systemic sclerosis (SS) and verified whether an association existed between osteoporosis (OP) and SS. They found that 28% of patients had OP of the lumbar spine, whereas 6% had OP of the femoral neck. Serum intact parathormone (iPTH) level was inversely correlated with low bone mass at the hip (P = 0.023, r2 = 0.121). Low bone mass did not correlate with age, postmenopausal status, corticosteroid use, low body mass index, serum 25 hydroxyvitamin D levels, disease duration, and the presence of interstitial lung disease or pulmonary arterial hypertension. They concluded that low bone mass was highly prevailing in SS patients, and it was associated with increased serum iPTH levels. The authors mentioned few study limitations that might cast suspicions on the accuracy of the study results. I assume that the following methodological limitations might be additionally relevant. In the study methodology, the authors obviously stated that “dual-energy X-ray absorptiometry (DXA) scan was performed using Hologic viewer 6.0 (Model-Discovery A [S/N 87292]) at the lumbar spine and left femoral neck, and T scores and Z scores were calculated as per the manufacturer's data. Patients with BMD T score ≤−1.00 were classified as “low bone mass,” and those with BMD T scores >−1.00 as “normal bone mass.” OP was defined as a T score below − 2.5 standard deviation (SD), and osteopenia was defined as a T score between −1.0 SD and −2.5 SD below the young adult mean (WHO standards).” It is explicit that the interpretation of DXA results requires the employment of population-specific reference values as evaluation of local and international reference databases for bone densitometry could result in different impacts on diagnostic decisions. The reference ranges employed by Sharma et al. are related to Caucasian population, and they are not worthy to be applied for Indian population. To my knowledge, Indian population-specific normative BMD reference curves for the reliable interpretations of individual DXA values have already been constructed to be employed in clinical settings and researches. I wonder why Sharma et al. did not refer to that national normative data in the study methodology. I assume that employing national curves could yield more accurate results on the prevalence of OP and associated factors in SS patients.
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| References|| |
Sharma S, Dhooria A, Singh T, Dhir V, Chattopadhyay A, Mishra D, et al
. Bone mineral density is decreased in patients with systemic sclerosis and correlates with serum intact parathormone levels: A cross-sectional study. Indian J Rheumatol 2019;14:109-12. [Full text]
Mészáros S, Berko P, Genti G, Hosszú E, Keszthelyi B, Kraszna, et al
. Comparative evaluation of local and international reference databases for forearm densitometry: Different impacts on diagnostic decisions. J Clin Densitom 2006;9:445-53.
Makker A, Mishra G, Singh BP, Tripathi A, Singh MM. Normative bone mineral density data at multiple skeletal sites in Indian subjects. Arch Osteoporos 2008;3:25-37.