From 5,650 in 2002 the number of 100-plus citizens had risen to 19,000 by last year, 83 percent of whom were women, the national health observatory reported.
Italy's ageing population was given as one of the reasons for a sharp spike in the number of deaths in 2015. The total of 54,000 was up nine percent on the 2014 figure.
The report's author, Alessandro Solipaca, said the impact of an outbreak of influenza early in the year and a summer heatwave had probably contributed to the trend by resulting in "avoidable deaths."
The report also noted that public health spending had fallen from €112.5 billion to 110.5 billion between 2010 and 2014. Per capita spending in 2014 was half the level of Canada's.
Life expectancy in 2015 was put at 80.1 years for men and 84.7 in 2015, down by a couple of months from the 2014 figure.