Who are the oldest old in Italy? Evidence from the Italian semi-super and supercentenarians survey

In a country, like Italy, where longevity is one of the most important demographic aspects, it.s crucial to study the population at extreme ages in order to understand the amount and the characteristics of individuals who live so longer. The study of the oldest-old individuals requests necessarily a validated data source not affected by over-coverage or under-coverage. In order to have a yearly corrected population register the Italian National Institute of Statistics (ISTAT) has developed the SSC survey with the aim of collecting data about alive and deceased semi-super and supercentenarians, and knowing how many of them are really verified. Due to record linkage operations with other ISTAT surveys and to the quality of the data collection, the SSC.s database is not implemented in any other country. It has been (and will be) an important data source to analyse longevity of population in order to contribute to study about lifespan and the human survival and to understand whether the extreme-age mortality plateaus in humans exist or not.