Ahead of today's U.S. Senate Special Committee on Aging's hearing, Wells Fargo analyst David Maris says he remains convinced that price increases have been and continue to be the key driver of Valeant Pharmaceuticals' growth. Despite payer and government scrutiny over pricing, Valeant has already raised prices on 16 products in 2016, Maris tells investors in a research note. Many of the same products saw large price increases last year as well, the analyst points out. He estimates that the average price of Valeant's top 30 products is up 78% year-over-year. Maris believes that as these price increases annualize in 2016-2017, Valeant's comps will become difficult and its growth could "slow dramatically." The company, with lower pricing ability, will likely have to rely more on volume growth, and volume trends in two key areas - dermatology and gastrointestinal - do not look good, Maris writes. He continues to see "significant risk" that Valeant will not be able to meet its larger debt maturities. The analyst keeps an Underperform rating on the shares with a $30-$31 price target range. Valeant closed yesterday up $1.06 to $36.22. The Wall Street Journal reported this morning that outgoing Valeant CEO Michael Pearson will tell the Senate committee today that his company has been too aggressive in raising drug prices.