From 1990 to 2017, stroke-associated mortality in Yunnan showed a declining trend, but the prevalence continued to increase, especially after 2010. This trend is similar to that in low-income and middle-income countries. In 2017, age-standardized prevalence of stroke was 1537.7 per 100,000 people, which was higher than the national average of 1115 per 100,000 according to the NESS-China survey. The majority of Yunnan consists of rural areas. Thus, the higher prevalence may be explained by the increased detection rate of stroke in rural areas. In addition, Yunnan has the lowest healthcare ratio per 1,000 individuals and significant differences in the distribution of medical resources[8, 9]. As the aging population continues to grow, the number of cases is expected to increase further, posing challenges for the healthcare system. Thus, we need to strengthen the healthcare system.
The disease burden of intracerebral hemorrhage was much higher than that of ischemic stroke and its rate of DALYs was also higher. According to the global age standards, DALYs of all stroke patients showed a decreasing trend from 1990 to 2017, but those of ischemic stroke increased by 5.8% in Yunnan, indicating the serious nature of disease burden of ischemic stroke in Yunnan. We need to pay greater attention to the trends in ischemic stroke. We observed that the rate of DALYs in stroke patients was higher in men than in women. This finding suggests that women live longer and the prevalence of smoking and alcohol consumption is much higher in men than in women from this population. It is essential to strengthen the healthcare framework for early detection, early intervention, and management of patients; to improve the survival rate; and to reduce the burden of disability caused by stroke .
In the 2017 GBD study, risk factors were grouped into behavioral, occupational/environmental, and metabolic risk categories. We observed that dietary risks, high BMI, and tobacco consumption were the main risk factors for stroke burden in Yunnan. Dietary habits are a major source of stroke disease burden, accounting for 67.5% of the DALYs in 2017. Yunnan’s per capita salt consumption is 11 g, which is significantly higher than the recommended dietary intake. Salt intake has been linked with an increased risk of high blood pressure and stroke and adherence to a healthy diet can reduce the lifetime risk of stroke by 20%. A healthy diet includes restricting the salt intake to 2–3 grams per day, limiting red meat intake, reducing the caloric intake from saturated and trans fats, and increasing fruit and vegetable intake.
Hypertension is the main pathogenic factor associated with the incidence and prognosis of common stroke, accounting for two-thirds of the incidence and DALYs of stroke in developing countries. In this study, the rate of DALYs of hypertension in Yunnan was 51.5%. In addition, a case-control study reported that the population attributable risk or stroke ratio can be attributed to high blood pressure in 54% of the crowd.
A higher prevalence of blood pressure in the population is associated with a higher risk of stroke. According to previous research, the prevalence of hypertension among ethnic minorities of Yunnan is higher than that in the general population (32.5%)[28, 29]. However, it is unclear whether alcohol consumption plays a role in the disease burden of stroke among ethnic minorities of Yunnan and requires further research.
In 2017, the contribution of smoking to DALYs in Yunnan reached approximately 33%. Smoking can lead to various diseases and research has shown that passive and former smokers have a higher risk of stroke than non-smokers. Moreover, there is a causal relationship between smoking and risk of ischemic stroke, but not between smoking and risk of hemorrhagic stroke. The prevalence of smoking is higher in men than in women, which may increase the disease burden of stroke in men. Government should monitor tobacco use, educate the population, and provide help in smoking cessation, especially in the tobacco-growing areas of Yunnan.
Although there was little change in the risk of stroke attributable to alcohol consumption from 1990 to 2017, it is a major risk factor for the global burden of disease . Increased alcohol consumption increases the risk of hypertension and stroke. A meta-analysis showed that mild to moderate alcohol consumption (two cups per day) was associated with a reduced risk of ischemic stroke, but not with that of intracerebral hemorrhage or subarachnoid hemorrhage. A high alcohol consumption rate among ethnic minorities might be responsible for the increased incidence of ischemic stroke in Yunnan. High alcohol intake is associated with an increased risk of all types of stroke. According to a report by the Chinese Center for Disease Prevention in 2015, Yunnan has the fourth highest daily alcohol consumption rate in China, which is higher than the national average. This might lead to an increased disease burden of stroke, but the relationship between local alcohol consumption and stroke requires further research.
BMI was the most modifiable risk factor from 1990 to 2017. Previous studies have shown a J-type correlation between BMI and hemorrhagic stroke. However, a recent narrative review suggests an obesity paradox in stroke (obese and overweight patients have lower mortality and better functional outcomes after stroke). The relationship between stroke and obesity needs to be clarified using high-quality evidence. Prevalence of obesity and hyperlipidemia is increasing in mainland China, since decades of economic development have changed people’s eating habits. Moreover, urbanization and industrialization have led to a decline in physical activity, especially in rural areas. These findings may explain the sharp increase in BMI.