It is known that surgical patients whose core body temperatures drop below 35 C (around 95 F) during surgery have significantly higher mortality rates than those whose temperatures stay above 35 C. Therefore, it is suggested that keeping operating rooms warmer than the current standard of 20 C (around 68 F) could reduce mortality rates during surgery.

Which of the following, if true, most strongly argues against the idea that increasing operating room temperatures would lower surgical mortality rates?