Democrats and Republicans locked horns Friday over inclusion of medical comparative effectiveness study language in a draft health care overhaul measure, suggesting that majority plans to spend only eight days debating and amending the bill may be ambitious.

Health, Education, Labor and Pension Committee members spent about 45 minutes arguing over just six words in the 615-page — and growing — legislation.

The debate — over a passage in the bill concerning how the government can use data developed from new “comparative effectiveness” studies of different medical treatments and procedures — illustrates both the almost infinite amounts of time Congress could consume debating the health overhaul, as well as the frustrating ease with which even seemingly minor issues can quickly become full-blown controversies.

The argument centered on an amendment by Pat Roberts , R-Kan., and Tom Coburn , R-Okla., aimed at forbidding Medicare from using comparative effectiveness research to deny paying for some medical procedures. Republicans fear such a policy could lead to “rationing” of care, a word the minority party tosses out with frequency in the health care debate.

Democrats say they don’t want Medicare or anyone else to use the research to deny care; they say they only want the information available to doctors to make better care decisions. And so the legislation reads that reports by a “Center for Health Outcomes” that will compile effectiveness research “shall not be construed as mandates” to make decisions regarding payment, coverage or treatment.