[1] Madrilenian Hlth Serv SERMAS, Madrid 28046, Spain
[2] Univ Valladolid, Fac Nursing, Nursing Dept, Valladolid 47005, Spain
[3] Castilla & Leon Hlth Serv SACYL, Valladolid 47007, Spain
[4] Univ Valladolid, Nursing Care Res GICE, Valladolid 47005, Spain