(RxWiki News) Smokers may face a number of serious health problems, including a higher risk for blood clots in the legs.
A recent review looked at a certain type of blood clot in current smokers, former smokers and people who had never smoked.
The researchers found that smoking increased the risk of developing a deep vein blood clot, and that the more cigarettes a person smoked, the greater the risk for developing the clot.
"Seek help to quit smoking."
Yun-Jiu Cheng, MD, from the Department of Cardiology at Sun Yat-sen University in China, led this study on smoking as a risk factor for blood clots.
Venous thromboembolism, or deep vein thrombosis (DVT), is a blood clot that occurs in a major vein deep in the body. More often than not, these types of blood clots are found in the legs.
According to the authors of this review, smoking may be a risk factor for developing a deep vein blood clot.
For the review, the researchers looked through multiple medical databases for studies from 1966 through 2013 on deep vein blood clots.
In 32 studies with 3,966,184 patients, a total of 35,151 deep vein blood clot events were recorded.
The researchers found that people who had ever smoked had a 17 percent higher risk for developing a deep vein blood clot compared with people who had never smoked.
Current smokers were 23 percent more likely to develop a deep vein blood clot compared with never smokers.
Former smokers were 10 percent more likely to experience a deep vein blood clot compared with never smokers.
For every additional 10 cigarettes that a person smoked each day, the risk for a deep vein blood clot increased by 10.2 percent.
For every additional 10 pack-years, the risk for a deep vein blood clot increased by 6.1 percent.
A pack-year is calculated based on the number of cigarettes a person smoked per day multiplied by the number of years he or she smoked. For example, if a person smoked 20 cigarettes per day, or one pack, for 10 years, that would equal 10 pack years.
Therefore, if someone smoked one pack a day for 40 years, he or she would have a 26.7 percent higher risk of developing a deep vein blood clot than a person who had never smoked.
Obesity can also be a risk factor for deep vein blood clots. Of the 32 studies, 13 provided body mass index (BMI) information about the patients.
After adjusting for BMI, which is a measure used to determine if someone is overweight or obese, the researchers found that current smokers were 30 percent more likely to have a deep vein blood clot compared with never smokers.
The authors of this review concluded that cigarette smoking was associated with an increased risk for deep vein blood clot events, and that the more a person smoked, the greater the risk of developing a deep vein blood clot.
"It is well known that smoking has harmful effects on the entire blood vessel system. Smoking increases one's chances of forming blood clots by increasing clotting factor concentrations, making platelets more likely to adhere to one another, blocking the body's natural anticoagulation abilities, and increasing blood viscosity," Adam Shapira, MD, an electrophysiologist on staff at The Heart Hospital Baylor Plano, told dailyRx News.
"It would not be surprising if these harmful effects of smoking, which increase one's risk of heart attack, also contribute to the risk of DVT," said Dr. Shapira.
This study was published in September in PLOS Medicine.
The Guangdong Province Natural Science Foundation, the Guangdong Province Science and Technology Program and the National Ministry of Education Scholarly Exchanges Foundation provided funding for this project. The authors declared no conflicts of interest.