Importance of the selected lower FIB-4 cutoff point
The FIB-4 index was initially established in HIV/HCV coinfected patients with a lower cutoff point of 1.45 2. Since then, different lower cutoff points have been evaluated 3. In the recently published article by Turner and colleagues 56.8% of patients had likely fibrosis on the basis of FIB-4 alone, whereas 42.6% of patients had likely fibrosis by FIB-4 plus imaging. In my opinion, the 14.2% difference may be due to the improper use of the lower FIB-4 cutoff point of 1.45, as in a recently published article by Kayadibi et al. 4 it was evidenced that use of the lower FIB-4 cutoff point of 1.62 had higher diagnostic accuracy than 1.45. If the authors had used a cutoff point greater than 1.45 for FIB-4, they may have obtained similar results as in FIB-4 plus imaging. This is because, when you increase the cutoff point for the diagnosis of likely fibrosis, the percentage of the disease of interest will decrease, and the positive predictive value will increase as false-positive results will reduce.
In conclusion, proper use of the lower FIB-4 cutoff point may decrease the need for additional diagnostic techniques like imaging or others for the prediction of patients with likely fibrosis.