Apo B/Apo A ratio
Regarding cut values for the apo B/apo A-I ratio, <0.9 and <0.8 may be used to define a risk level for males and females, respectively.
The large prospective AMORIS study, which published its first report of the relationship between lipid levels and cardiovascular events in 1992, was designed specifically to assess the power of apo B, apo A-I and the apo B/apo A-I ratio for predicting fatal acute MI or sudden death, and whether apo B and apo A-I added predictive power over and above that of TG, TC and LDL-C levels.Raised apo B levels, an increased apo B/apo A-I ratio and low levels of apo A-I were highly predictive of risk of fatal MI in univariate analyses.
Furthermore, in multivariate analyses, high apo B levels, high apo B/apo A-I ratio and low levels of apo A-I were stronger predictors of risk than LDL-C, TC and TG levels.
The predictive value of apo B and apo A-I is maintained in patients on lipid-modifying therapy.
The methods for measuring apo B and apo A-I are now internationally standardized by the World Health Organization–International Federation of Clinical Chemistry (WHO-IFCC). Values of apo B >1.2 g/L, and for apo A-I < 1.2 g/L , have been proposed as cut values.
Thus, in those at greatest risk, a target apo B level below 0.9 g/L is recommended regardless of gender. However, as males in general have lower apo A-I values than females, it may be more relevant to have different cut values for males (< 1.15 g/L) and females (<1.25 g/L).
Regarding cut values for the apo B/apo A-I ratio, <0.9 and <0.8 may be used to define a risk level for males and females, respectively.