Reducing The Number Of Cigarettes You Smoke Will Not Help, Says New Study; This Will

Smoking is one of the most prominent causes of mortality across the globe. According to the World Health Organisation (WHO), smoking causes over 8 million deaths each year globally. It causes several chronic diseases like cancer, lung disease, heart disease and stroke, among others. Smoking is also one of the leading causes of preventable deaths. WHO also states that tobacco use leads to approximately 1.35 million deaths each year in India. Smoking, its impact and how quitting it benefits health is also at the centre of several studies.

A recent study published in PLOS Medicine highlights how smoking intensity and cessation can impact your heart, health and more. According to reports, smoking increases the risk of cardiovascular disease (CVD) by two times and also shortens life span by five or more years. Studies have also found links between smoking and heart disease such as atrial fibrillation and other cardiac arrhythmias.

Previous studies on smoking cessation

Earlier studies have shown that when you stop smoking, the excess risk of death reduces by 90% to 95%, within the first three years after quitting. Within 10 years of quitting smoking, excess mortality is almost eliminated, which restores nearly a decade of life expectancy.

Most people tend to reduce the number of cigarettes they smoke each day. Between 2005 and 2014, the proportion of adults smoking fewer than ten cigarettes per day increased from 16 per cent to 27 per cent. During the same period, the percentage of non-daily smokers rose from 19 to 23 per cent. The link between smoking a few cigarettes per day and cardiovascular disease (CVD) has not been well established. The new study aimed to understand this relationship and establish how quitting duration affects health outcomes.

Study overview

For the study, the researchers analysed data from 22 large cohort studies included in the Cross-Cohort Collaboration Tobacco Working Group. The team examined three main variables; number of smoking years, cigarettes per day (CPD), and years since quitting, and compared these factors against major cardiovascular and mortality outcomes.

These outcomes included heart attack, stroke, heart disease, heart failure, atrial fibrillation, and death from any related cause. Participants of the study were followed for nearly 50 years, with some tracked for up to 20 years individually.

The data included 3,23,826 adults, who accounted for more than 25 million person-years of follow-up. Of these, 1,76,396 deaths occurred, representing 16 million person-years at risk. The median age of participants was around 60, and women made up about three-quarters of the study sample. Fourteen per cent were current smokers, 36 per cent had never smoked, and nearly half were former smokers. On average, current smokers consumed 20 cigarettes per day, while former smokers had quit for approximately 21 years.

Who faced the greatest risk?

Study results showed that current smokers faced substantially higher risk for every measured outcome compared to people who never smoked or those who had quit. Among men who smoked, the risk of developing cardiovascular disease was 74 per cent higher than non-smokers, while women faced more than double that risk. All-cause mortality was equally alarming; male smokers were 117 per cent more likely to die from any cause, and female smokers faced a 143 per cent increase compared with those who never smoked.

Importantly, even very light smoking had real danger. People who smoked one cigarette or less per day still faced higher risk of most heart outcomes compared with never-smokers. Those who smoked between two and five cigarettes daily had a 26 per cent higher risk of atrial fibrillation and a 57 per cent higher risk of heart failure. Their risk of death from cardiovascular causes rose by 57 per cent, while overall mortality increased by 60 per cent. For those smoking between 11 and 15 CPD, the risk was even more severe; 87 per cent higher for CVD and 130 per cent higher for all-cause mortality.

Results from other studies

These observations are similar to those of other research that suggest that newer generations of smokers tend to start earlier, smoke more intensely, and continue longer than previous generations. This points to an increased long-term health burden, reinforcing the need for public health programs focused on prevention and early cessation rather than reduction alone.

Benefits of quitting

The impact of quitting smoking was both immediate and long-term. The first decade after cessation brought the largest reduction in risk, but health benefits continued to accumulate for decades. After 20 years of quitting, former smokers had about an 80 per cent lower risk of cardiovascular disease and death compared with current smokers. The greatest benefit appeared among those who quit at younger ages, highlighting that it is never too early to stop.

Even among heavy smokers, quitting reduces the danger. Former smokers in the highest exposure group still had lower cardiovascular risk than current smokers in the lowest exposure group. Duration of cessation was a stronger predictor of cardiovascular outcomes, while total pack-years more accurately predicted mortality.

The overall message is clear. Smoking, even at very low levels, significantly increases the risk of heart disease and early death, and hence, cutting down is not enough. The greatest health benefit comes from quitting completely, and the earlier this happens, the better the outcomes.

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