Increased risk for coronary heart disease after avascular necrosis of femoral head: A 3-year follow-up study

Background: Although pathomechanisms of avascular necrosis (AVN) of the femoral head are not well-known, vascular and coagulation abnormalities have been proposed as hypotheses. We propose that the pathomechanisms of AVN could also involve the cardiovascular system. This study explores the risk of coronary heart disease (CHD) after AVN, through a population-based case-control approach. Methods: We identified 1,450 patients with AVN as the study group and randomly selected 7,250 patients as the comparison group. Each patient was individually tracked for 3 years to identify all who developed CHD during the follow-up period. Cox proportional hazards regressions were performed to calculate the hazard ratios (HRs) of CHD for the 2 groups. Results: In total, 90 patients (6.21%) from the study group and 295 patients (4.07%) from the comparison group developed CHD during the follow-up period. Compared with patients in the comparison group, the HR for CHD among patients with AVN was 1.43 (95% CI 1.10-1.86, P = .002), after adjusting for geographic variables and cardiovascular risk factors. Among males, the adjusted HR for CHD was 1.65 (95% CI 1.20-2.27, P <.001). For patients