Background Treatment of Paget's Disease of Bone (PDB) has been revolutionized by the use of zolendronic acid (ZA). Patients usually have a dramatic response to treatment with normalization serum alkaline phosphataise (ALP) levels and a longer period of clinical remission, compared with other class agents. Data from long-term use are scarse.
Objectives Evaluate the effectiveness and safety of ZA in PDB patients, as well as remission, re-treatment rates and side effects in our outpatient population since 2005.
Methods A retrospective study of PDB patients treated with 5 mg ZA intravenous infusion at our day-care center. Follow up time, demographic and clinical characteristics, previous therapeutic agents, rate of response, number and reasons of re-treatment(s) and rates of adverse events were collected. A descriptive statistic analysis was made.
Results 48 patients, 60% female, mean age of 75 years, with a median time since the diagnosis of 12.3 years. The disease was poliostotic in 73% of the patients and pelvis (65%), skull (29%) and spine (27%) were the most common pagetic localizations. Deafness was present in 12.5% and 65% had hip involvement. 44% patients had been treated with another biphosphonate agent previously. Response rates were 97.9% at 1 year, 87.2% after 2 years and 95.1% after 3 years. The mean ALP levels before ZA infusion was 290 UI/L and after 112 UI/L. Sixteen patients needed a re-treatment in the period of follow up, minimum of 1 year after the ZA infusion and maximum of 8 years after. 56.3% due to raised of ALP levels and 43.8% due pain/ hip involvement. Four patients needed a third infusion due to hip involvement, and 2 of them a forth infusion due to the same reason. All of the patients re-treated due to hip involvement had severe hip involvement at time of diagnosis. In our population, 2 patients achieved 10 years remission, 5 patients 9 years remission and 10 patients 8 years remission with a single ZA infusion. Recording adverse effects were: 14.6% Flu like symptoms (7 patients), 2% assintomatic hypocalcemia (1 patient) and no reports of osteonecrosis or fractures. All of these effects were reported after the first ZA infusion.
Conclusions In our population, we find high long-term sustained remission rate. Only sixteen patients needed re-treatment. Patients maintained sustained remission up to 10 years of a single ZA infusion. Incidence of adverse events was similar to the reported in the literature.
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Disclosure of Interest None declared