Prooxidant-antioxidant balance as a predictor of mortality: findings from the Neyshabur Longitudinal study on Ageing.

Background: The aim of this study was to determine PAB levels as a predictor of all-cause and cause-specific mortality in adult and elderly subjects.

Methods: The data from 386 subjects who had died during the study were age- and sex-matched to 386 subjects that remained alive, and PAB levels were compared. PAB was evaluated using a mixed enzymatic/chemical method involving simultaneous oxidation and reduction of the chromogen 3,3',5,5'-tetramethylbenzidine by prooxidants and antioxidants, respectively, leading to measurable colorimetric changes.

Results: PAB levels showed an increased risk of mortality (OR: 1.018; 95%CI: 1.010-1.025, p < 0.001) for each unit increase of PAB (per SD increase). When divided into quartiles, the PAB value was significantly higher for all-cause mortality in quartiles 2,3 and 4 compared with quartile 1 (PAB <34.95). Using uni & multivariate conditional logistic regression with multiple adjustments, the PAB value remained significantly different for all-cause mortality. The result of the cause-specific mortality analysis showed that the mean PAB was highest in COVID-19 infection and the respiratory diseases, and lowest in death caused by cardiovascular diseases (p < 0.05).

Conclusions: Increasing PAB levels were significantly associated with increasing all-cause mortality suggesting that PAB measurement may have utility in indicating disease severity and have differential prognostic value in acute and chronic clinical scenarios.