By Caroline Humer

NEW YORK (Reuters) – AbbVie Inc’s rheumatoid arthritis drug Humira and Roche Holding AG’s cancer drug Rituxan topped a list of seven treatments whose combined 2017 and 2018 price hikes accounted for a $5.1 billion increase in U.S. spending, a report released on Tuesday showed.

The price hikes were more than twice the rate of medical inflation and were not supported by any new clinical evidence, the Institute for Clinical and Economic Review (ICER) said in the analysis.

It was the first such annual report by the Boston-based research group, which assesses the cost-effectiveness of drugs.

Other top treatments by spending that were called out in the report were Pfizer Inc’s pain drug Lyrica, Gilead Sciences Inc’s HIV drug Truvada, Amgen Inc’s white blood cell booster Neulasta, Eli Lilly & Co’s erectile dysfunction drug Cialis and Biogen Inc’s multiple sclerosis treatment Tecfidera.

U.S. drug prices are tough to pin down. Companies may provide list prices, but they also negotiate discounts and after-market rebates with purchasers and their representatives such as pharmacy benefit managers, health insurers, employers, and government and state health coverage programs.

Drugmakers have been under increasing political scrutiny to lower costs to consumers and have responded by limiting annual list price hikes to under 10% in many cases.

ICER evaluated the pricing in partnerships with SSR Health Inc, a research firm, which calculated the increases excluding discounts and after-market rebates.

AbbVie spokeswoman Adelle Infante said that ICER’s data on its net pricing is inaccurate and called into question the group’s methodology.

Roche spokeswoman Emmy Wang said that in pricing drugs, the company strived for the right balance between patient access and investing for breakthroughs in medicine.

Gilead, Biogen, Pfizer and Eli Lilly questioned ICER’s analysis, methodology and conclusions, with Lilly spokesman Mark Taylor noting that generic versions of Cialis were now available for up to 90% less than the retail price.

Amgen did not have an immediate comment.

ICER acknowledged it was difficult to determine the actual increase in spending on the drugs, but said it was confident that the seven drugs cost a lot more.

Pricing drugs based on new benefits could help slow cost hikes, ICER Chief Medical Officer David Rind said.

“If manufacturers weren’t raising prices if they haven’t shown a new important benefit, I think that would help,” he said.

Celgene’s multiple myeloma drug Revlimid and Gilead’s HIV treatment Genovya were also large contributors to spending but were excluded from the list because of their clinical advancements, ICER said.

Humira’s net price increase over 2017 and 2018 added $1.8 billion in spending, while Rituxan added $806 million, the report said.

(Reporting by Caroline Humer; Editing by Richard Chang and Bill Berkrot)