Skip to main content
. 2022 Jun 23;25(3):395–403. doi: 10.1093/ntr/ntac149

Table 2.

Incidence of Adverse Event and Respiratory Symptoms

Group* Events Weeks† Rate‡ IRR (95%CI)‡ HR (95%CI)‡
Adverse events
Any Control 24 144 1.67 Ref Ref
E-cigarette 31 193 1.61 0.96 (0.57–1.66) 0.69 (0.40–1.20)
Sleep disturbance Control 21 163 1.29 Ref Ref
E-cigarette 20 283 0.71 0.55 (0.30–1.02) 0.64 (0.34–1.20)
Nausea Control 14 209 0.67 Ref Ref
E-cigarette 18 261 0.69 1.03 (0.51–2.11) 0.84 (0.41–1.72)
Throat/mouth irritation Control 7 244 0.29 Ref Ref
E-cigarette 18 310 0.58 2.02 (0.88–5.21) 1.11 (0.45–2.74)
Respiratory symptoms
Any Control 19 164 1.16 Ref Ref
E-cigarette 25 258 0.97 0.84 (0.46–1.54) 1.05 (0.57–1.92)
Phlegm Control 13 210 0.62 Ref Ref
E-cigarette 20 293 0.68 1.10 (0.55–2.27) 0.75 (0.37–1.53)
Cough Control 14 200 0.70 Ref Ref
E-cigarette 17 301 0.56 0.81 (0.40–1.66) 1.49 (0.72–3.08)
Shortness of breath Control 8 225 0.36 Ref Ref
E-cigarette 12 332 0.36 1.02 (0.42–2.59) 1.22 (0.48–3.10)
Wheezing Control 6 249 0.24 Ref Ref
E-cigarette 7 381 0.18 0.76 (0.25–2.37) 0.85 (0.26–2.82)

There were 44 participants in the varenicline-only (control) group and 48 in the e-cigarette varenicline (e-cigarette) group.

Total person-weeks at risk of first event. For each person, this is the number of weeks from the quit date until they either experienced the event/symptom, were lost to follow-up, or completed the study (12 weeks post quit).

Incidence rate calculated per 10 person-weeks. Incidence rate ratios (IRR) and corresponding 95% confidence intervals (95%CI) estimated using log-linear rate models. Hazards ratios (HR) and corresponding 95% CIs estimated using Cox proportional-hazards models. Schoenfeld tests found some evidence for nonproportional hazards for throat/mouth irritation (p = .046) and cough (p = .032), but all other outcomes were compatible with proportionality (p > .31).