How well do ICD-9 physician claim diagnostic codes identify confirmed pertussis cases in Alberta, Canada? A Canadian Immunization Research Network (CIRN) Study. - Fathima S; Simmonds KA; Drews SJ; Svenson LW; Kwong JC; Mahmud SM; Quach S; Johnson C; Schwartz KL; Crowcroft NS; Russell ML (BMC health services research, 2017)