Establishing Reference Intervals of Aspartate Aminotransferase-to-Platelet Ratio Index for Apparently Healthy Elderly

Background: Aspartate aminotransferase (AST) to platelet ratio index (APRI) serves as a parameter in evaluating liver fibrosis in current clinical practice. However, reference standard (reference intervals, RIs) or baseline levels of APRI have not been previously reported. The purpose of this paper is to establish the reference intervals of APRI in apparently healthy elderly people from the region of Shuyang, China. Methods: Blood specimens were collected from local elderly residents (selected 51,263 elderly Han Shuyang Chinese from 65 to 97 years old, 32.97% males and 67.03% females) by standard procedures. Complete blood counts were determined by Sysmex XE-2100 analyzer and the AST values were measured by a TBA2000FR automatic biochemical analyzer (Toshiba Co., Ltd., Japan). The 95% reference intervals were calculated by using the non parametric method according to the document: Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline-Third Edition (C28-A3) of CLSI. Results: RIs established for healthy elderly include: 0.1398 - 0.6266 for males and 0.1282 - 0.5798 for females (0.1284 - 0.5086 for 65 - 74 years old; 0.1209 - 0.5704 for >= 75 years old). RIs of APRI for elderly males were higher than those of females, and values of APRI increased with increasing age for females. Conclusions: We established scientific and reasonable His of APRI for the healthy elderly in our region.