The number of Medicare Part D beneficiaries who reach the catastrophic coverage phase of the prescription drug benefit rose by more than 50% between 2013 and 2016, according to an analysis recently released by Avalere. The study looked at the 72% of Part D beneficiaries who do not receive low-income subsidies and found more than 800,000 entered the catastrophic coverage phase in 2016, up from about 515,000 in 2013.