Smoking cessation lowers coronary artery calcification risk
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Patients with chronic kidney disease who previously smoked less than 10 pack-years and had long-term smoking cessation had a reduced risk of prevalent coronary artery calcification compared with current smokers, according to a study.

“Current clinical guidelines in the kidney disease field recommend smoking cessation as a lifestyle modification. However, these guidelines are mostly derived from epidemiologic observational studies involving participants without CKD,” researchers wrote. “To date, studies on the association between smoking and cardiovascular disease in patients with CKD have yielded conflicting results.”

To investigate the association smoking dosage and cessation duration have on coronary artery calcification (CAC) in patients with CKD, researchers conducted a long-term nationwide prospective cohort study in South Korea of patients with CKD. The 1,914 patients included had a diagnosis of prevalent CAC as defined by an Agatston unit (AU) score of greater than zero. The mean age of patients was 54 years and most were men.

Researchers collected patient data from the Korean Cohort Study for Outcome in Patients with CKD between 2011 and 2016. Upon study enrollment, investigators collected patients’ baseline demographics and clinical data, including comorbidities, cause of CKD, economic status, educational level and medications. Patients underwent an 8-hour fasting blood test and urine test for biochemical variables. They also took a structured questionnaire on their smoking history. CAC progression involved at or above a 30%/year increase in AU score at the 4-year follow-up.

The researchers found CAC in 50% of patients and among these individuals, the median AU was 67. Patients who never smoked had the lowest CAC prevalence rate (42%), while current smokers had the highest (59%). Nonsmokers had a median AU score of 0, former smokers had an AU score of 4 and current smokers had an AU score of 8. Lee and colleagues noticed a remarkably higher rate of smoking among men (75%) compared with women (8%), although prevalence of CAC was consistently higher among current smokers no matter patients’ sex.

Compared with former smokers, current smokers saw a 1.25-folder higher prevalence of CAC. Patients who identified as former smokers with a lower smoking load (less than 10 pack- years) and who had a longer duration of smoking cessation had a lower risk of prevalent CAC compared with current smokers. Prevalence ratios did not vary between patients who never smoked and those who had long-term cessation. Patients with short-term cessation and a heavy smoking load had a higher risk of prevalent CAC (prevalence ratio, 1.21) compared with those who never smoked. CAC progressed in 33% of patients and compared with nonsmokers, former smokers showed a similar risk of CAC progression, although current smokers had a higher risk (relative risk, 1.92).

“This study also showed that current smokers were more likely to have CAC than never smokers. However, whether quitting smoking can prevent further calcification is currently unknown,” researchers wrote.