AB1028 REGRESSIVE BONE MINERAL DENSITY TRENDS SEEN WITH DELAY IN FOLLOW UP OF DENOSUMAB TREATMENT DUE TO THE PANDEMIC INDUCED LOCKDOWN - A SINGLE CENTRE INDIAN EXPERIENCE.

Abstract

BackgroundDenosumab (Dmab), a fully human monoclonal antibody that inhibits receptor activator of nuclear factor kappa-β ligand (RANKL), which selectively inhibits osteoclastogenesis can be used for a long period unlike the relatively short period with Teriparatide.1-2 However the effects of Dmab can quickly regress if the treatment is delayed.3ObjectivesThe pandemic led to multiple prolonged lockdowns since March 2020 to Jan 2022 in India. This resulted in follow up Dmab treatment delays. The retrospective study was aimed to look for the effect of the delays.MethodsThe bone mineral density (BMD) trends from the central dual-energy x-ray absorptiometry (DXA) at our centre were studied. The trends of patients under Dmab for one year and delay in follow up for 10 - 12 months for the forth dose were evaluated. 21 postmenopausal women who had been under treatment with Dmab 60 mg subcutaneous injection at 6 monthly interval for one year followed up with such delays. 6 were excluded because of history of sars-cov-2 infection and glucocorticoid use. In the study group of 15 (n=15), the mean BMD at L2, L3 & L4 (sp BMD) and Right and Left Hip (hip BMD) were studied from before treatment (a BMD), 6 months after 1st and at the time of 2nd injection (b BMD), 6 months of the 2nd and at the time of 3 rd injection of Dmab (c BMD), and that due to delay in follow up of 10-12 months (d BMD). The mean percentage trend change between a-b, b-c, and c-d BMDs was evaluated. The least significant change (LSC) 4 from a single centre DXA was used to validate the findings.ResultsThe mean percentage change after the treatment for the 1st 6 months of Dmab (a-b BMD) was 4.08% and 3.60% and the second injection resulted in a further change (b-c BMD) of 5.98% and 4.52% in the sp BMD & hip BMD respectively. The delay in follow up of 10-12 months resulted in a change (c-d BMD) of -7.81% in the sp BMD and -2.96% in the hip BMD. The LSC from a single centre DXA is 2.6% and 3.6% for sp BMD and hip BMD respectively. A p>0.05 was considered statistically significant. Table 1 shows the BMD changes.Table 1.Percentage BMD changesBMD trend (n=15)sp BMD (LSC – 2.6%)hip BMD (LSC – 3.6%)a-b BMD4.08%3.60%b-c BMD5.98%4.52%c-d BMD-7.81%-2.96%sp BMD - Mean of L2,L3 & L4 Spine BMD, hip BMD - Mean of Right and Left Hip BMD, a-b BMD - Percent change in BMD from before to 6 months after Ist & at the time of 2nd Dmab, b-c BMD - Percentage change in BMD 6 months after 2nd & at the time of 3rd Dmab, c-d BMD - Percentage change in BMD after 3rd Dmab & follow up after delay of 10-12 months and LSC – Least significant change.ConclusionThese findings suggest that regressive trend in BMD are seen when the treatment with Dmab is delayed even as early as 10 to 12 months. It was seen much faster in the spine compared to the hip.It is therefore advised that short term treatment with Dmab without follow up could lead to loss of all gains and may also worsen the osteoporosis.