(S (S (S (BASENP (NNP Vioxx)) (VP (VBD was) (VP (VP (VBN pulled) (PP (IN from) (BASENP (DT the) (NNS shelves)))) (PP (IN in) (BASENP (NN 2004)))))) (SBAR (IN after) (S (BASENP (DT a) (NN study)) (VP (VBD discovered) (SBAR (S (S (BASENP (PRP it)) (VP (MD could) (VP (VB double) (NP (BASENP (DT the) (NN risk)) (PP (IN of) (NP (DT a) (NP (BASENP (NN heart) (NN attack)) (CC or) (BASENP (NN stroke))))))))) (SBAR (IN if) (S (VP (VBN taken) (PP (IN for) (NP (QP (ADVP (RBR longer) (IN than)) (NN 1.5)) (NNS years)))))))))))) (PERIOD .))