Electronic and conventional cigarette use and risk of spinal disc disorders: a nationwide cohort study

Liquid electronic cigarettes (LECs), heat-not-burn electronic cigarettes (HECs), and combustible cigarettes (CCs) pose varying disc disease risks.

To assess disc disease risk among LEC, HEC, combined LEC/HEC, and CC users and nonsmokers, including those transitioning from CCs to LECs or HECs.

This was an observational, nationwide, population-based retrospective cohort study using data from the Korean National Health Insurance Service.

Data from 3,265,293 adults in the Korean National Health Insurance Service database were analyzed.

The primary study outcome was spinal disc disease hazard ratios.

Participants were categorized as LEC, HEC, combined LEC/HEC or CC users or never-smokers. Propensity score matching and multivariable Cox proportional hazards regression estimated adjusted hazard ratios (aHRs) for disc disease risk. Smoking status was self-reported, and detailed quantitative exposure data were unavailable, which may limit interpretation of hazard ratios.

Increased disc disease risk was found in smokers than in nonsmokers: CC (aHR=1.174 [95% confidence interval (CI), 1.158-1.191]), LEC (aHR=1.153 [95% CI, 1.079-1.232]), HEC (aHR=1.132 [95% CI, 1.063-1.204]), and combined LEC/HEC (aHR=1.174 [95% CI, 1.01-1.366]). Switching from CC to HEC reduced the risk compared to that after continuous CC use (aHR=0.89 [95% CI, 0.838-0.944]). However, the risk remained higher than that in nonsmokers (aHR=1.092 [95% CI, 1.026-1.163]). Switching from CC to LEC showed risk similar to that with continuous CC use (aHR=1.01 [95% CI, 0.902-1.132]) and higher risk than that in nonsmokers (aHR=1.339 [95% CI, 1.185-1.513]).

CC smokers present the highest risk of spinal disc disease. LEC and HEC smokers have lower risks than CC smokers but higher risks than nonsmokers. Transitioning from CCs to HECs reduces disc disease risk, but switching to LECs does not, compared to continuous CC use.