WASHINGTON (Bloomberg) — Insurance companies including WellPoint Inc. and Aetna Inc. don't provide consumers the benefits they paid for, which is why the industry needs close supervision, US Senator Jay Rockefeller said yesterday.

Many insurers spent less revenue from premiums on medical care than is called for under the health overhaul passed last month, according to a report released by Rockefeller's office. The legislation requires insurance companies to spend at least 85 percent of the premium revenue for large group insurance on medical care, and 80 percent of the revenue for individual and small group insurance.

While individual insurers now decide what categories to include in the ratio, the health law demands that all companies classify medical costs the same way beginning in 2011. What will be included under the ratio is being developed by Health and Human Services Secretary Kathleen Sebelius, with the input of state insurance commissioners.

Only Cigna Corp. among the six largest US insurers met the 80 percent threshold for the individual market in 2009, according to the report. Aetna spent 76 percent of premiums on medical care, while Humana Inc. spent 68 percent. The data in the report is from the Kansas City, Missouri-based National Association of Insurance Commissioners, which regulates insurance companies at the state level.