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‘Secondhand smoke increases stroke risk by 30% ’

By Chukwuma Muanya with agency reports
15 July 2015   |   12:57 am
A new study published in the American Journal of Preventive Medicine found that secondhand smoke (SHS) increases the risk of stroke by about 30 percent for nonsmokers. Using data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national, population-based, longitudinal study investigating cardiovascular disease events and mortality endpoints among white…
Stroke

PHOTO CREDIT: HUFFPOST

A new study published in the American Journal of Preventive Medicine found that secondhand smoke (SHS) increases the risk of stroke by about 30 percent for nonsmokers.

Using data from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national, population-based, longitudinal study investigating cardiovascular disease events and mortality endpoints among white (55 percent) and African American (45 percent) adults aged greater than 45 years, investigators found that even after adjustment for other stroke factors such as hypertension, diabetes, and heart disease, the 30 percent risk for nonsmokers remained.

The current study included almost 22,000 participants (38 percent African American, 45 percent male) with 23 percent reporting SHS exposure in the past year. During the period of April 2003 to March 2012, 428 strokes were reported. A further analysis of the type of stroke (ischemic vs. hemorrhagic) was performed and showed that most strokes were due to blockage of blood flow to the brain (352 ischemic, 50 hemorrhagic, and 26 strokes of unknown subtype).

The literature concerning adverse health effects of SHS is becoming clearer, although not all studies have replicated the association between SHS exposure and stroke.

According to lead author Angela M. Malek, PhD, of the Department of Public Health Sciences, Medical University of South Carolina, Charleston, “Previous studies suffer from limitations in that few were prospective, adjustment for potential confounders has varied, stroke and SHS exposure have not been consistently defined, measurement and sources of SHS exposure have differed, stroke subtypes have not always been assessed, and some studies have been underpowered due to small sample size.”

The strengths of the current study result from the use of a population-based sample of a large, prospectively followed, well-characterized group of people that includes a large proportion of African Americans and physician-adjudicated incident strokes.

Also, a combination of smoking and giving birth preterm can more than triple the risk of cardiovascular disease faced by mothers, according to the findings of a new study published in the European Journal of Preventive Cardiology.

The study authors wanted to find out whether the coexistence of smoking and preterm birth would combine to result in further increases in maternal cardiovascular disease risk.

The authors also found that the risk of cardiovascular disease (CVD) increased for mothers in a dose-response relationship with how many and how severe the preterm births were.

While smoking is recognized as a risk factor for CVD, women are particularly dissuaded against it if they become pregnant. In addition to the usual risks, smoking can expose babies to harmful chemicals while in the womb, hinder growth and increase the risk of preterm birth and certain postbirth health problems.

Preterm birth is also known to increase the risk of CVD, with previous studies revealing that women with a history of preterm birth have a 1.2-4 times higher risk of CVD than women who have term babies.

To find out whether the two conditions would combine to increase the overall CVD risk faced by mothers, the researchers looked at the perinatal records of 902,008 mothers during 1994-2011 alongside records for any hospital admissions or deaths from CVD.

The researchers discovered that the two conditions – smoking and preterm birth – were both independently and significantly associated with an increased risk of CVD. Compared with nonsmokers who had term births, smoking mothers who gave birth preterm were 3.35 times more likely to develop CVD.

The risk of CVD for smoking mothers increased in comparison with nonsmoking mothers with term births according to the severity of the preterm births. Extremely preterm births (20-33 weeks gestation) increased CVD risk 3.83 times and moderately preterm (34-36 weeks gestation) births increased CVD risk 3.18 times.

Recurrent preterm births among smoking mothers also increased CVD risk. Smoking women with two or more preterm births were 4.47 times more likely to develop CVD, while smoking mothers with just one preterm birth were 3.2 times more likely – both in comparison with nonsmoking women with term births.

Unfortunately, as the study only categorized mothers as having never or ever smoked, the researchers were unable to analyze the effects of smoking severity or whether the women smoked throughout their pregnancy or quit.

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