Incidence of polycythemia vera in a defined population.

In this retrospective investigation from Malmö, a city well-suited for epidemiologic studies, 177 patients (88 males and 89 females) with polycythemia vera (PV) were identified between 1950 and 1984. The incidence rate (number of cases/100,000/yr) in both sexes increased significantly, being 1.0 in 1950-1959 and 2.6 in 1980-1984 (adjusted to the European age-standardized population). This is the highest rate reported to date. In 1970-1984 the highest age-specific incidence rates (number of cases/100,000/yr) were found in males greater than or equal to 80 yr and females 70-79 yr of age, being 18.3 and 14.6, respectively. A subgroup of 12 (7%) was identified where the PV diagnosis was not obvious on entry into the study but where it became clear during follow-up. 16 PV patients (9%) had verified or suspected arterial hypoxemia caused by a concomitant condition. We conclude that the increasing PV incidence rates, mainly confined to older age groups, are probably due to better case ascertainment.