Jan 13 (Reuters) - Biogen Idec Inc (BIIB.O) said on Tuesday the number of patients taking its multiple sclerosis drug Tysabri slowed in the fourth quarter compared to the third quarter amid concerns over its safety.
Slides included in a regulatory filing with the U.S. Securities and Exchange Commission showed the number of patients taking Tysabri worldwide rose 5.9 percent in the fourth quarter to 37,600, up from 35,500 at the end of the third quarter.
Biogen's filing coincides with a presentation to investors at the JP Morgan Healthcare conference in San Francisco.
The figures represent a slowdown compared to the growth rate in the third quarter, when the number of new patients rose 11.6 percent over the 31,800 reported in the second quarter.
For the alerts, double-click [ID:nWNAB9405] (Reporting by Suzannah Benjamin in Bangalore; Editing by Deepak Kannan)