Post-hoc analysis showed a highly significant decline from the decade 1981–1990 compared to all later decades, with the most significant peak compared to the decades 2001–2010 and 2011–2020 ( p < 0.001) (Table 1 )(Fig. 3 C).
Change in the hunt and hess grade Throughout the decades of the study period, ANOVA analysis of the HH good grade showed a significant trend in the severity of aSAH, with the percentage of patients presenting with HH good grade decreasing by an average of 5.49% per decade ( p = 0.004).