[Features of Paget's disease of bone in a new high-prevalence focus].

We report the features of a group of 41 patients with Paget's disease (PD) who were identified in a cross sectional study in the "Sierra de la Cabrera" (Madrid). As the screening test, we used serum alkaline phosphatase quantification, and the diagnosis was confirmed by radiological study. This biochemical parameter shows an excellent diagnostic performance, with a sensitivity of 98% and a specificity of 85%. The prevalence in the population over 40 years of age is 6.37% (95% CI 4.79-7.95) which, comparing it with that from other areas, suggests that this region is a "focus" of PD. 51% of cases had the characteristic symptoms of the disease, bone pain being the most common (44%). We compared the abnormalities in the patients with those of a control group with strictly comparable features, and we found that bone deformity (34%) and a localized increase in skin temperature (27%) were the most discriminative data, while cranial symptoms (26%) were nonspecific. Cataracts and actinic keratosis were associated with PD in the crude analysis (p less than or equal to 0.01). When age was controlled for, the statistical significance of cataracts disappeared, whereas that of actinic keratosis was maintained (odds ratio 4.08, p less than or equal to 0.01). A high family incidence was found, with 15 proven cases (36.5%) in 6 families. Apart from a marked increase in alkaline phosphatase (mean: 407 mU/ml), other abnormalities or biochemical differences with the control were not found. These results suggest an interaction of genetic and environmental factors, and is wholly consistent with the multifactorial etiological hypothesis of PD.