Homocysteine (Hcy) levels are strongly associated with vascular health problems like stroke, and early identification and screening for hyperhomocysteinemia (HHcy) is crucial for stroke prevention. However, lack of systematic epidemiological data on the relationship between Hcy and stroke in Hebei Province, China, and insufficient comprehensive studies on HHcy and other risk factors limit the development of effective prevention and control strategies.

To investigate the correlation between Hcy and stroke in people aged 40 years and over in Hebei Province, thus providing scientific basis for the development of accurate stroke prevention and control strategies.

On the basis of the China National Stroke Screening Survey from January 2018 to December 2020, 92 942 permanent residents aged 40 and above were sampled from 49 monitoring sites in 9 cities of Hebei Province by multi-stage cluster sampling method. The correlation between Hcy and stroke was investigated by unconditional Logistic regression analysis, and stratified analysis was performed based on age and sex. At the same time, the combined effects of Hcy and other factors on stroke were further studied.

The prevalence of stroke among people aged 40 years and above in Hebei Province was 4.51% (4 196/92 942) , and the prevalence of high Hcy was 36.25% (33 692/92 942) . The prevalence of stroke in people with high Hcy levels was significantly higher than that in people with normal Hcy levels (P<0.05) . Stratified by Hcy quartiles, the prevalence of stroke tended to increase as Hcy levels gradually increased (χ² _trend=367.310, P<0.05) . The results of stratification analysis showed that in two age groups (40-59 years old and ≥60 years old) , the prevalence of stroke was significantly higher in people with high Hcy levels than in people with normal Hcy levels (P<0.05) . With the incremental increase of Hcy levels from Q1 to Q4, the prevalence of stroke in people with 40-59 and ≥60 years old showed an incremental trend (the trend χ² values were 109.213, and 75.653, respectively, P<0.05) . The prevalence of stroke was significantly higher in both males and females with high Hcy levels than normal Hcy levels (P<0.05) , and the prevalence of stroke in both males and females showed an increasing trend as the Hcy level increased from Q1 to Q4 (the trend χ² values were 197.115, and 117.406, respectively, P<0.05) . There was a positive additive interaction but no multiplicative interaction between high Hcy and hypertension (RERI=0.41, AP=0.08, SI=1.12, P<0.05) , and a negative additive (RERI=-0.30, AP=-0.25, SI=0.41, P<0.05) and negative multiplicative (OR=0.77, 95%CI=0.64-0.92, P<0.05) interactions. No interaction was found with diabetes or alcohol consumption.

The prevalence of high Hcy exceeded 36% in people over 40 years of age in Hebei province, and the prevalence of stroke increased with higher Hcy levels, especially across age and gender. The risk of stroke was increased when high Hcy coexisted with hypertension, whereas there was a negative interaction between high Hcy and smoking, with an antagonistic effect when the two exposure factors coexisted that altogether reduced the risk of stroke. However, it should be emphasized that the reduced risk does not mean that the harms of these two factors alone can be ignored, and that high Hcy and smoking are still important risk factors for stroke. Therefore, people at high risk of stroke should have their Hcy levels monitored regularly, and should take targeted measures to control their blood pressure, improve healthy lifestyles, and take folic acid and B vitamins supplements to reduce the overall risk of stroke.