Angiotensin-converting enzyme gene polymorphism may influence blood loss in a geriatric population undergoing total hip arthroplasty

OBJECTIVES: To evaluate how angiotensin-converting enzyme (ACE) gene polymorphism is associated with perioperative blood loss in hip arthroplasty in a geriatric population. DESIGN: A case-control study of subjects consecutively undergoing total hip arthroplasty. SETTING: A department of orthopedic surgery in Italy. PARTICIPANTS: One hundred five patients, mean age +/- standard deviation 68.6 +/- 10.4, undergoing total hip arthroplasty. MEASUREMENTS: ACE gene polymorphism was analyzed using polymerase chain reaction. Decrement of hemoglobin (Hb) and hematocrit (Ht) was calculated as the difference between the preoperative and the lowest postoperative value, measured 1, 2, and 3 days after surgery. Total blood loss was calculated as the sum of intra- and postoperative blood loss. RESULTS: Patients carrying the deletion homozygous and insertion/deletion heterozygous genotypes of the ACE gene show a higher decrement of Hb (P <.01) and Ht (P <.01) and higher total blood loss (P <.007) after hip surgery than subjects carrying the insertion (II) homozygous. The role of ACE gene polymorphism seems hypertension independent. Logistic regression analysis showed that II genotype reduces total blood loss. CONCLUSIONS: This is the largest study evaluating the distribution of ACE gene genotypes in patients undergoing hip arthroplasty and the first investigating the association between bleeding and ACE gene polymorphism. Our data suggest that II genotype is associated with lower total blood loss.