Officials last month said they planned to change the statistical analysis of a jointly sponsored study of Vytorin, a drug that combines two anti-high-cholesterol drugs -- Merck & Co.'s Zocor and Schering-Plough's Zetia, the Wall Street Journal reported. The study aims to determine if the drugs combined make the now-off-patent Zocor more effective.

If Zocor is more effective in combination, insurers would be more inclined to approve $3-a-day Vytorin than cheaper, generic forms of Zocor, the Journal said.

Study results are expected in March.