Health effects in COPD smokers who switch to electronic cigarettes: a retrospective-prospective 3-year follow-up

Abstract

Background: Health effects of electronic cigarette (EC) use in patients with chronic obstructive pulmonary disease (COPD) are largely unexplored.

Aim: We present findings from a long-term prospective assessment of respiratory parameters in a cohort of COPD patients who ceased or substantially reduced conventional cigarette use with ECs.

Methods: We prospectively re-evaluated COPD exacerbations, spirometric indices, subjective assessments (using the COPD Assessment Tool [CAT] scores), physical activity (measured by the 6-minute walk distance [6MWD]), and conventional cigarette use in EC users with COPD who were retrospectively assessed previously. Baseline measurements prior to switching to EC use were compared to follow-up visits at 12, 24, and 36 months. Age- and sex-matched regularly smoking COPD patients who were not using ECs were included as reference (control) group.

Results: Complete data were available from 44 patients. Compared to baseline in the EC-user group, there was a marked decline in the use of conventional cigarettes. Although there was no change in lung function, significant improvements in COPD exacerbation rates, CAT scores, and 6MWD were observed consistently in the EC user group over the 3-year period (p<0.01). Similar findings were noted in COPD EC users who also smoked conventional cigarettes ("dual users").

Conclusion: The present study suggests that EC use may ameliorate objective and subjective COPD outcomes and that the benefits gained may persist long-term. EC use may reverse some of the harm resulting from tobacco smoking in COPD patients.

Keywords: COPD; electronic cigarette; smoking cessation; tobacco harm reduction.

Figure 1

Changes in the number of COPD exacerbations per year from baseline, at follow-up visit 1 (12±1.5 months), visit 2 (24±2.5 months), and visit 3 (36±3 months) separately for COPD EC users (closed triangles) and COPD controls (closed circles). All data are expressed as mean and error bars are standard deviation of the mean. The ^** and ^*** indicate the within-group p-value of <0.01 and <0.001, respectively, compared to baseline. Abbreviations: COPD, chronic obstructive pulmonary disease; EC, electronic cigarette.

Figure 2

Changes in the FEV₁ (A) and FVC (B) from baseline, at follow-up visit 1 (12±1.5 months), visit 2 (24±2.5 months), and visit 3 (36±3 months) separately for COPD EC users (dark gray boxes) and COPD controls (light gray boxes). The boxes represent the 25th to 75th percentiles; the line in the boxes indicates the median, and error bars are 5th and 95th percentiles. Abbreviations: COPD, chronic obstructive pulmonary disease; EC, electronic cigarette; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; BL, baseline.

Figure 3

COPD GOLD stage changes over the study period. Abbreviations: COPD, chronic obstructive pulmonary disease; EC, electronic cigarette; BL, baseline; GOLD, Global Initiative for Chronic Obstructive Lung Disease.

Figure 4

Changes in the CAT scores from baseline, at follow-up visit 1 (12±1.5 months), visit 2 (24±2.5 months), and visit 3 (36±3 months) separately for COPD EC users (dark gray boxes) and COPD controls (light gray boxes). The boxes represent the 25th to 75th percentiles; the lines in the boxes indicate the median, and error bars are 5th and 95th percentiles. The ^** and ^*** indicate the within-group p-value of <0.01 and <0.001, respectively, compared to baseline. Abbreviations: COPD, chronic obstructive pulmonary disease; EC, electronic cigarette; BL, baseline; CAT, COPD Assessment Tool.