Objectives: Paget's disease is a chronic bone disorder of unknown cause. Recent studies have reported an unexplained reduction in both prevalence and disease severity. We undertook a radiographic survey to determine the current prevalence of Paget's disease in New Zealand (previously recognized as a high prevalence area).
Methods: A total of 3350 plain abdominal radiographs taken in 2005-06 in subjects of European descent >54 years old were examined for Paget's disease. The results were compared with those of a similar survey from 1996-98. The medical record of affected subjects was examined to determine when the disease had been first recognized and the plasma ALP at that time.
Results: Paget's disease was detected in 87 radiographs (2.6%). In 55 cases (63%), it was already known to have been present, for a mean 14 years beforehand. The newly recognized or 'incident' cases were significantly older (mean age 86 vs 67 years, P < 0.0001) and had milder disease (ALP 139 vs 239 u/l, P < 0.0001) than the known cases. Compared with the 1996-98 survey, the age distribution of affected patients was shifted to the right, with a significantly lower proportion in the youngest age group (55-69 years, P < 0.004).
Conclusions: These results confirm the secular trend of Paget's disease presenting later in life and in milder form, suggesting that there are important environmental determinants. The relatively few 'incident' cases are mostly in the very elderly. Given the secular trend and limitations to life expectancy, it is predicted that Paget's disease will become increasingly rare.