A prominent Massachusetts anesthesiologist allegedly fabricated 21 medical studies that claimed to show benefits from painkillers like Vioxx and Celebrex, according to the hospital where he worked.

Baystate Medical Center, Springfield, Mass., said that its former chief of acute pain, Scott S. Reuben, had faked data used in the studies, which were published in several anesthesiology journals between 1996 and 2008.

The...