Prevalence of liver abnormalities in healthy aircrew: A histopathological examination of autopsy samples and possible etiologies

Objectives A substantial number of ostensibly healthy aircrew has incidentally shown liver abnormalities during routine medical assessments, posing challenges in their fitness evaluation. This study aimed to suggest the possible etiopathology behind such aberrations by integrating histopathological findings of liver samples and clinical data retrieved from the autopsy records of the same cohort of healthy aircrew. Material and Methods This retrospective cross-sectional study encompassed 22 years, studying the autopsy records of deceased aircrew following fatal aircraft accidents. The inclusion criteria comprised healthy aircrew between the ages of 20 and 55 years, who held a medical category of A1G1 or an equivalent rating. Alcohol intake, whether occasional or none was noted. Exclusion criteria covered aircrew with lower medical categorization or those with obesity (Body mass index [BMI] >30 kg/m 2 ), pre-existing systemic diseases such as jaundice, cardiovascular disease, liver disease, diabetes mellitus, and chronic alcoholism. The archived microscopic slides of liver specimen were meticulously evaluated for histopathological abnormalities. Results Out of the 167 cases included in the study, macrovesicular steatosis was found in 23.8% individuals. The Chi-square test did not reveal a significant correlation between steatosis and alcohol intake (χ 2 = 0.724, P = 0.39). The severity of macrovesicular steatosis was graded using the Non-Alcoholic Fatty Liver disease (NAFLD) activity scoring (NAS) system, with scores of 0, 1, 2, 3, and 4 found in 75.9%, 12.7%, 7.8%, 3.0%, and 0.6%, respectively. Both univariate and multivariate analysis was conducted using logistic regression to assess the correlation between age, BMI, and steatosis which yielded significant results. The odds ratios of age-adjusted for BMI and BMI adjusted for age for occurrence of steatosis were 1.11 and 1.57, respectively. Ordinal regression confirmed the association of age and BMI with increasing severity of steatosis, in agreement with the logistic regression results. Conclusion Macrovesicular steatosis accounted for 95.8% of histopathological abnormalities in the liver and was associated with increasing BMI an age, rather than alcohol intake. The severity of macrovesicular steatosis was limited to a maximum NAS score of 4, distinguishing it from non-alcoholic steatohepatitis (NASH), which requires a NAS score of ≥5. Thus, the macrovesicular steatosis was linked to uncomplicated NAFLD, in contrast to NASH, which is an irreversible condition and carries a graver prognosis. The most likely etiopathology underlying incidental and often transient liver abnormalities including elevated liver enzymes with or without hyperbilirubinemia and fatty liver detected during ultrasonography is NAFLD. The predominant finding of uncomplicated NAFLD, along with the absence of full-blown NASH and alcoholic liver disease, brings positive news since dietary and lifestyle modifications can potentially treat a majority of these cases.