Stroke up 30 percent since 2001 in HK’s ≤55-year-olds

Researchers from the University of Hong Kong (HKU) report that the incidence of “young stroke” (ie, strokes occurring in those aged 18–55 years) has increased by 30 percent in Hong Kong’s residents since 2001.

According to WHO data, stroke is the second most common cause of death and a leading cause of disability in the world. Although the overall incidence of stroke has been declining in high-income countries, the incidence of stroke among the younger populations has been rising globally. [Stroke 2020;51:1372-1380; J Neurol Neurosurg Psychiatry 2020;91:411-417]

The HKU researchers used the Clinical Data Analysis and Reporting System of Hong Kong’s Hospital Authority (HA) to analyze the 2001–2021 trends of stroke in Hong Kong. It was found that the crude incidence of young stroke has sharply increased from 39.1 cases per 100,000 people in 2001 to 48.3 cases per 100,000 people in 2011 and 55.7 cases per 100,000 people in 2021. Although the total number of new stroke cases admitted to HA hospitals remained similar at around 13,500–14,000 per year during the past 20 years, the number of young stroke cases increased from 1,531 in 2001 to 2,028 in 2021.

To identify risk factors of young stroke, the researchers also followed a cohort of 431 stroke patients aged 18–55 years who were admitted to Queen Mary Hospital and Ruttonjee Hospital in Hong Kong between September 2019 and August 2022. Among these patients, 53 percent had hypertension, 44 percent had hyperlipidaemia, 26 percent had a history of smoking, 19 percent were obese, and 17 percent had diabetes. Of patients who were found to have hypertension, hyperlipidaemia and diabetes, 33 percent, 64 percent and 23 percent were newly diagnosed with the respective conditions only at the time of hospital admission for stroke.

“These alarming findings call for stronger awareness and control of vascular risk factors leading to stroke, especially among the younger generations,” commented study leader, Dr Gary Lau of Stroke Research and Prevention Group at HKU. “Hypertension is the leading modifiable risk factor of stroke. Previous studies have shown that with every 20 mm Hg increase in systolic blood pressure or 10 mm Hg increase in diastolic blood pressure, there is a 30–50 percent increase in the risk of stroke.” [Lancet 2014;383:1899-1911]

In a separate study, 284 apparently healthy Hong Kong Chinese volunteers aged 40–65 years received 24-hour blood pressure monitoring. Results revealed that approximately 40 percent of the individuals had hypertension. Their average daily sodium intake, which is strongly correlated with systolic and diastolic blood pressure and 10-year projected stroke risk, was estimated at 14 g in men and 13 g in women, far exceeding WHO’s recommended daily intake of ≤5 g per day.

“Consistent with other studies, our findings show that Chinese people tend to have a very high sodium intake, which is directly correlated with blood pressure and projected stroke risk.  Hypertension, hyperlipidaemia and diabetes are often the result of poor lifestyle and dietary practices. Measures to control these vascular risk factors through better diet with significantly lower sodium intake, regular exercise and smoking cessation are strongly recommended for stroke prevention,” said Lau.