Risk for perioperative myocardial infarction and mortality in patients undergoing hip or knee arthroplasty: the role of anemia

BACKGROUND: Anemia is common in patients undergoing surgery. This study was designed to determine whether preoperative anemia represents an independent risk factor for 30‐day mortality and nonfatal myocardial infarction (death/MI) in patients undergoing major orthopedic arthroplasty surgery. STUDY DESIGN AND METHODS: Between January 1987 and December 2006 at the Mayo Clinic, 391 orthopedic patients experienced death/MI within 30 days of the index surgery. For each patient included in the event cohort (case), one control patient (1:1 ratio) was identified matched according to sex, age, type of joint operation (hip vs. knee vs. bilateral knee), primary operation versus revision, emergent versus elective, and date of surgery. Association of preoperative hemoglobin (Hb) with death/MI was assessed by multiple linear regression including preoperative Hb and all other characteristics and comorbid conditions found to have some evidence (p