Background: In the last few years, it has been reported a secular change of Paget disease of bone (PDB), expressed as a reduction of prevalence¹ and severity, assessed by disease extent².

Objectives: To retrospectively evaluate the baseline clinical and demographic characteristics of a contemporary cohort of patients affected by PDB, compared with a cohort of a previous decade³.

Methods: Data were retrospectively extracted from a monocentric registry, which included PDB patients at their first evaluation in a tertiary rheumatology Center between January 2000 and September 2018. Descriptive data of baseline characteristics included demographics, presenting manifestation and diagnostic procedures (diagnosed by chance or by investigations requested for specific clinical manifestations), extent of PDB, and biochemical data. Patients were divided into two groups according to the year of first evaluation: group 1 before July 2007, group 2 after July 2007. Comparisons between the two groups were performed by T test and chi-square test; logistic regression was used to analyze the association between disease extent and other collected variables.

Results: The overall population included 368 patients (males (M) 57.6%, mean age at diagnosis [± standard deviation, SD] 62.0±12.4 yrs). Diagnosis was made by chance in 43.8% cases, 54.3% patients had symptoms at disease onset; 49.5% was monostotic, mean serum alkaline phosphatase at presentation (sALP) was 198.5±167.5 UI/L.

Group 1 included 217 patients (M 56.2%, mean age at diagnosis 61.0±11.6 yrs, 6.5% family history of PDB; 45.6% diagnosed by chance, 51.2% had symptoms at disease onset, mean sALP 218.9±11,7, 43.3% monostotic). Group 2 included 151 subjects (M 59.6%, mean age at diagnosis 64.3±11.1 yrs, 7.3% family history of PDB; 41.1% diagnosed by chance, 62.9% had symptoms at disease onset, mean sALP 162.7±14,2,58.3% monostotic).

Poliostotic disease was significantly higher in Group 1 vs Group 2 (p=0.007), and the odd to have a poliostotic disease was higher in Group 1 [OR 1.82 (IC 1.2-2.8), p<0,005]. sALP was significantly higher in Group 1 vs Group 2 (218,9±11,7 vs 162,7±14,2; p=0,003). No differences were found in sex, age at diagnosis, presence of family history of PDB between patients diagnosed incidentally or by symptoms.

Conclusion: Our data confirm the reduction of clinical severity, assessed by the proportion of skeleton involved, and the decrease of biochemical markers over time. The reduction of the disease extent is consistent with a serological biomarker of the disease, such as mean sALP levels.

References [1] Michou L, et al. JBS2016;83: 650–655.

[2] Tan A, Ralston SH. Calcif Tissue Int2014;95:385–392.

[3] Varenna M, et al. J Rheum2010;37:155-160.

Disclosure of Interests: Chiara Crotti: None declared, Francesca Zucchi: None declared, Andrea Becciolini: None declared, Luigi Sinigaglia Speakers bureau: Yes, I,ve been invited speaker by Amgen, Ely Lilly, UCB, Abbvie, Roche and BMS., Massimo Varenna: None declared