'Alarming' Increase in Stroke Risk Factors

October 17, 2017

Despite many prevention initiatives, the prevalence of conventional stroke risk factors, including hypertension, diabetes, dyslipidemia, drug abuse, and smoking, actually appears to be on the rise among new ischemic stroke patients in the United States, a new study shows.

Other vascular conditions, such as chronic renal failure, coronary artery disease, and carotid stenosis, also appear to be increasing in the acute ischemic stroke population.

These observations come from a new analysis of data from the Nationwide Inpatient Sample, which includes 922,451 hospitalizations for acute ischemic stroke. The authors say this represents "the most comprehensive assessment to date of temporal trends in the prevalence of major stroke risk factors."

The study was published online in Neurology on October 11.

"Our data show that all risk factors increased from 2004 to 2014 and the prevalence of raised cholesterol more than doubled during this time. These are truly alarming findings," lead author, Fadar Oliver Otite, MD, University of Miami Miller School of Medicine, Florida,  told Medscape Medical News.

"While we are putting a great deal of effort into trying to control cardiovascular risk factors, this is not adequate. We need more coordinated strategies to try and tackle this problem," he added.

However, an accompanying editorial points out some limitations of the study and cautions against interpreting the data at face value. 

Results of the study show that across the 2004–2014 period, 92.5% of patients with acute ischemic stroke had one or more risk factors. Overall the age- and sex-adjusted prevalence of hypertension was 79%; diabetes, 34%; dyslipidemia, 47%; smoking, 15%; and drug abuse, 2%.  In addition, 13% of patients had carotid stenosis, 12% had chronic renal failure, and 27% had coronary artery disease.

The analysis suggested that during the study period the prevalence of hypertension increased annually by 1.4%, diabetes by 2%, dyslipidemia by 7%, smoking by 5%, and drug abuse by 7%. Prevalence of chronic renal failure increased annually by 13%, carotid stenosis by 6%, and coronary artery disease by 1%.

During the whole 10 years of the study, diabetes prevalence increased from 30.7% in 2004 to 37.5% in 2014 in all patients, with higher rates in Hispanics and blacks than in whites. By 2014, 50% of Hispanic participants with acute ischemic stroke had diabetes. Stroke admissions with both hypertension and diabetes increased from 25.1% in 2004 to 34.2% in 2014.

Overall dyslipidemia prevalence more than doubled during the study period — from 28.9% in 2004 to 58.6% in 2014. Admissions with concomitant hypertension, diabetes, and dyslipidemia increased by more than 200% from 9.4% in 2004 to 23.7% in 2014.

In terms of other vascular diseases, chronic renal failure saw the largest increase — from 4.8% in 2004 to 15.0% in 2014.

"These results indicate that modifiable stroke risk factors continue to pose significant challenges for AIS [acute ischemic stroke] prevention in the United States and call for intensification of proven treatment strategies and development of novel comprehensive preventive approaches," the researchers write.

Noting that many of the risk factors are higher in blacks and Hispanics, they suggest that "specific interventions targeting these underrepresented populations may potentially yield major gains for ischemic stroke prevention."

They further point out that fewer than half of patients with dyslipidemia are receiving treatment for this condition and only around 30% have control of their low-density lipoprotein cholesterol. And up to half of the 75 million patients with hypertension in the United States have uncontrolled blood pressure and about 20% of patients with diabetes have hemoglobin A1c levels more than 9.0 mg/dL.

"Focusing on risk factor control is critical for stroke prevention," they conclude. "Our alarming findings support the call for further concerted action from all stakeholders to more effectively implement evidence-based interventions to reduce stroke risk."

But in the accompanying editorial, Shyam Prabhakaran, MD, points out that these new data contrast with other those from studies from Norway and the United Kingdom that found reductions in most stroke risk factors between 1995 and 2011.

He suggests that the Nationwide Inpatient Sample has several limitations that make it a suboptimal dataset from which to make epidemiologic inferences, including nonstandardized definitions of risk factors across hospitals, potential for coding errors and misclassification of risk factors, and changing definitions of various conditions during the study period.

He also notes that the lack of data on risk factor management and control "provides little insight on whether risk factors are simply accumulating unbeknownst to patients and therefore untreated, or whether they are being screened for, diagnosed early, and treated appropriately.

"Thus, instead of a national crisis of increasing risk factors among stroke patients, these same data could imply improved screening and diagnosis of multiple stroke risk factors prior to or at the time of stroke occurrence."

In addition, Dr Prabhakaran makes the point that an increasing prevalence of risk factors may also be explained by the declining cardiovascular and stroke mortality  because more people with multiple risk factors survive longer.

"So, while there should indeed be a call to action to prevent stroke and its negative consequences on society, we should acknowledge important progress that has been made in stroke prevention, even if there is much more work to be done," he concludes.

"We should also continue to search for data that measure the health of our society, but remain cautious in interpreting them in a vacuum or without the appropriate context."

Dr Otite has disclosed no relevant financial relationships.

Neurology. Published online October 11, 2017. Abstract, Editorial

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