UK cost agency doesn't favour UCB arthritis drug

* NICE "minded not to recommend" Cimzia

* Agency cites limitations with economic models

* UCB shares open down 0.5 percent

LONDON, Oct 20 (Reuters) - Britain's healthcare cost-effectiveness watchdog said on Tuesday it was "minded not to recommend" UCB's (UCB.BR) drug Cimzia as a treatment option for rheumatoid arthritis.

A National Institute for Health and Clinical Excellence (NICE) committee said there were limitations in submitted economic models for the drug, which led to a "high degree of uncertainty".

NICE decides which drugs should be given to patients using Britain's state-run health service.

It recommends limited use of three other anti-TNF drugs, which work in a similar way to Cimzia by blocking an inflammatory protein. Humira is sold in Europe by Abbott Laboratories (ABT.N), Enbrel by Pfizer (PFE.N) and Remicade by Schering-Plough SGP.N.

UCB shares opened down 0.5 percent.

(Reporting by Ben Hirschler; editing by John Stonestreet)