[1] Univ Autonoma Barcelona, Fac Med, Dept Nursing, Barcelona, Spain
[2] Grp Recerca Multidisciplinar Salut & Soc GREMSAS, Barcelona, Spain
[3] Fdn Canaria Inst Invest Sanitaria Canarias FIISC, Las Palmas Gran Canaria, Spain
[4] Red Invest Serv Salud Enfermedades Cron REDISSEC, Madrid, Spain
[5] Barcelona Grad Sch Math, Barcelona, Spain
[6] Univ Autonoma Barcelona, Dept Matemat, Barcelona, Spain
[7] Fdn Huesped, Buenos Aires, DF, Argentina