Novel insights into estimating the postmortem interval: red cell distribution width - standard deviation

Estimation of the postmortem interval (PMI) is highly significant, and many estimation methods have been developed. However, as no estimation method is determinate, several methods must be combined to achieve an accurate estimation. Therefore, the more methods available, the more accurate the estimation. To facilitate this, we examined whether red cell distribution width standard deviation (RDW-SD) was associated with PMI. We compared the RDW-SDs of blood samples from hospitals and autopsies in the same cadavers using a paired test. Additionally, we performed an unpaired test with multiple regression analysis to confirm the relationship between PMI and RDW-SD. Eighteen cases were included in the paired analysis, and a significant difference between hospital and autopsy RDW-SDs was confirmed. The 95% confidence interval for the difference was between 11.7 and 17.4. In the multiple regression analysis of the 756 cadavers, the 95% confidence interval of the regression coefficient of PMI for RDW-SD was 1.63-3.43. Our results suggest that RDW-SD may have a positive relationship with PMI. However, further research is required to determine the accuracy of this estimation method.