Different Changing Patterns for Stroke Subtype Mortality Attributable to High Sodium Intake in China During 1990 to 2019

Background: It is unclear whether sodium intake had similar effects on mortality of stroke subtypes. The purpose of this study is to compare the long-term trends in mortality of stroke subtypes attributable to high sodium intake in China during 1990 to 2019.

Methods: Data for China in the GBD (Global Burden of Disease) 2019 study were obtained mainly from the Chinese surveillance systems and the KaiLuan Study. The trends in stroke mortality due to high sodium intake (>5 g/d) were evaluated using join-point regression and age-period-cohort methods adjusting for age, period, and cohort.

Results: The age-standardized mortality rates of stroke attributable to high sodium intake showed downward trends during 1990 to 2019 in China, with an average annual percentage change of -0.6 (95% CI, -0.8 to -0.4) for ischemic stroke, -2.5 (95% CI, -2.8 to -2.2) for intracerebral hemorrhage, and -6.1 (95% CI, -6.6 to -5.7) for subarachnoid hemorrhage. The curves of local drifts, which reflected the average annual percentage change of stroke mortality due to high sodium intake across age groups, showed a slow upward trend with age for ischemic stroke, a slow downward trend for intracerebral hemorrhage, and a sharp downward trend for subarachnoid hemorrhage. The high sodium-related mortality increased dramatically with age for ischemic stroke and intracerebral hemorrhage, while it reached a peak at 50 to 70 years old for subarachnoid hemorrhage. The period and cohort rate ratios of stroke mortality due to high sodium intake decreased in the past 3 decades, with the greatest decline for subarachnoid hemorrhage and the weakest decrease for ischemic stroke. Notably, men had higher high sodium-related mortality and risk but slighter declines for all stroke subtypes than women.

Conclusions: Our results provided powerful evidence that high sodium-related age-standardized mortality rates and risk of stroke in China decreased in the past 3 decades, with diverse changing patterns for different stroke subtypes, highlighting that salt reduction had distinct impact on stroke subtypes.