Paget's disease of bone: Clinical and epidemiological characterisation of the population of a Portuguese tertiary centre.

Abstract

Paget's disease of bone (PDB) is the second most common metabolic bone disorder. We aimed to characterize the clinical and demographic profile of a Portuguese PDB cohort, identify factors associated with polyostotic disease, and compare retreatment needs between patients treated with zoledronate or alternative first-line therapies. Retrospective, longitudinal, single-centre cohort study. Demographic and clinical data were collected. Associations with polyostotic disease were assessed using parametric and non-parametric tests and multivariable logistic regression. Drug survival was analysed with Kaplan-Meier analysis, and retreatment rates compared using log-rank test and Cox regression. Eighty patients diagnosed between 1974 and 2021 were included; 58.8% were female and age at diagnosis was 63.0 ± 12.2 years. Most patients (72.5%) were born in rural areas, with clustering in Alentejo. Forty-one patients (51.2%) had polyostotic PDB. Vertebrae, femur, pelvis, sacrum and skull involvement were associated with polyostotic disease. Seventeen patients (22.1%) required retreatment. Mean first-line drug survival with zoledronate was 16.0 years (95% CI 14.3-17.6) compared to 11.7 years (95% CI 4.9-18.4) with other drugs. Drug survival was significantly lower with non-zoledronate therapy, with higher retreatment rates (crude HR 9.49 [95% CI 3.28-27.44]; log-rank p < 0.001), even after adjustment (adjusted HR 10.10 [95% CI 2.12-48.0]; p = 0.004). This study, the largest Portuguese PDB cohort, highlights a predominance in rural areas, identifies skeletal sites linked to polyostotic disease, and shows zoledronate is associated with significantly lower retreatment rates.