Is paget disease of bone more common in South India? Clinical characteristics, therapeutic outcome and follow-up of 66 patients from Tamil Nadu

Introduction: Paget disease of bone (PDB) is a disorder of altered bone remodeling mainly characterized by increased osteoclastic activity. While the exact Indian prevalence remains unknown, a clustering of published cases suggests South Indian predominance. Objective: To study the clinico-biochemical profile and therapeutic response of patients with PDB and briefly review the epidemiology of PDB from an Indian perspective. Materials and Methods: Retrospective data was collected from the charts of patients who have been seen in endocrine out-patient clinics in Tamil Nadu over a 12-year period. Published literature on PDB from India was reviewed. Results: A total of 66 patients (71% males) predominantly from Tamil Nadu were studied. The mean age at presentation was 67 ± 8 years. Polyostotic involvement was seen in 89% and familial occurrence of PDB in 5 patients. Symptoms at presentation mainly included bone pain (51%) and skeletal deformities (18%). Scalp vein sign (21%) and sensorineural hearing loss (64%) were also noted. Incidental PDB detection by raised serum alkaline phosphatase (SAP) levels was observed in 17% and by abnormal fluorodeoxyglucose-positron emission tomography (FDG-PET) scan in 6% of cases. Mean SAP at presentation was 606 ± 438 IU/L (Normal, 76-140). Major skeletal site involvement includes pelvis (62.1%) and spine (34.8%). Mean (range) follow-up of the cohort was 3.4 yrs (1-12 yrs). In all, 64 subjects received zoledronate and two received alendronate, and mean (SD) SAP at 1-year was 73 ± 42 IU/L. All but two showed remission at the end of 1 year. Two had pathological fractures and two had sarcomas. A review of epidemiology of PDB in Indian literature clearly showed a South Indian predilection for unclear reasons. Conclusion: In our cohort of PDB, male gender, polyostotic involvement, and hearing impairment were noted in more than two-thirds of patients and single-dose intravenous zoledronate was effective in normalizing SAP in almost all patients. PDB is intriguingly more common in South India and this needs more exploration.