Although several studies have indicated an association between tobacco smoking and increased risk of pancreatitis, others assessing the potential link have not found an association. Research into the risk factors of pancreatitis has been limited and not confirmed a dose-response relationship between smoking and pancreatitis risk. “If there is a dose-response relationship between an increasing number of cigarettes smoked per day or pack-years of smoking this could strengthen causal inferences,” explains Dagfinn Aune, PhD. To better understand the association between smoking and pancreatitis, Dr. Aune and colleagues analyzed previous studies with the hopes of determining whether the studies’ results could strengthen causal inferences for pancreatitis risk and further confirm current pancreatic health recommendations to abstain from smoking.
In a paper published in Pancreatology, Dr. Aune and colleagues conducted a systematic review and meta-analysis of prospective cohort studies on tobacco smoking and pancreatitis to clarify the association. The study team analyzed 10 studies published through April 2019 that reported on adjusted relative risk (RR) estimates for the association between cigarettes smoked per day or pack-years and pancreatitis. The team used random-effects models to determine RR association of smoking status (current, former, ever, or never), cigarettes per day, and pack-years with risk of acute, chronic, and combined acute and chronic pancreatitis. The team estimated linear trends of cigarettes per day and pack-years to analyze dose-response.
Review and analysis of the data indicated a significant dose-response relationship between an increasing number of cigarettes per day or pack-years and increasing risk of acute pancreatitis (Figure). The researchers found that compared with never smokers, current, former, and ever smokers had summary RRs for acute pancreatitis of 1.49 (1.29-1.72), 1.24 (1.15-1.34), and 1.39 (1.25-1.54), respectively. The studies collectively indicated that current and former smokers had RRs for chronic pancreatitis of 1.93 (1.60-2.32) and 1.30 (1.08-1.57), respectively, when compared with never smokers. This trend was consistent in assessments of combined acute and chronic pancreatitis. “We found 49% and 24% increases in the RR of acute pancreatitis in current and former smokers, respectively, when compared with never smokers,” highlights Dr. Aune. “In chronic pancreatitis, we found 93% and 30% increases, respectively, in the RRs for the same comparison. For acute and chronic pancreatitis combined, we found 62% and 29% increases in RR among current and former smokers, respectively, when compared with never smokers.”
Additionally, the RR for acute pancreatitis per 10 cigarettes smoked per day was 1.30 (1.18-1.42); per 10 pack-years, it was 1.13 (1.08-1.17). Similarly, there was a significant increase in RR for chronic pancreatitis (22%) per 10 pack-years in current smokers. “There was evidence of increasing risk with increasing number of pack-years,” adds Dr. Aune. For combined acute and chronic pancreatitis, summary RRs were 1.62 (1.29-2.03) for current smokers and 1.58 (1.24-2.02) for former smokers. “Lower risk in former smokers indicates that quitting smoking helps reduce the risk of both acute and chronic pancreatitis and supports recommendations for smoking cessation,” emphasizes Dr. Aune.
“Our findings suggest that smoking increases the risk of both acute and chronic pancreatitis and can be observed in both men and women,” explains Dr. Aune. “Considering that there was a dose-response relationship between increasing number of cigarettes smoked per day or pack-years and pancreatitis risk—as well as evidence from experimental animal studies supporting these findings—these results provide strong evidence that smoking increases pancreatitis risk.”
When considering further research, Dr. Aune believes researchers should further assess the relationship between duration of smoking cessation and risk. “Further studies on duration of smoking cessation in relation to pancreatitis risk could further clarify the association with subtypes of pancreatitis, including gallstone-related and non-gallstone-related pancreatitis,” he says.