Compared to fax , free-media referrals were 13 times more likely to be recruited ( OR 13.0 , 95 % CI 4.2 , 40.4 : p < 0.001 ) and paid-media referrals were 4 times more likely to be recruited ( OR 4.6 , 95 % CI 2.1 , 10.3 : p < 0.001 ) .