Vitamin E supplementation and pneumonia risk in males who initiated smoking at an early age: effect modification by body weight and dietary vitamin C

Table 3 Lightest participants (body-weight < 60 kg) initiating smoking at ≤ 20 years: relative risk of hospital-treated pneumonia by vitamin E supplementation

		Intervention		Effect of vitamin E
		Vitamin E	No vitamin E
Subgroup	No. of participants	No. of cases	No. of cases	RR (95% CI)*	P-value for interaction
All	935	41	25	1.84 (1.11–3.0)
BMI †
< median	467	25	17	1.87 (0.99–3.5)	0.8
≥ median	468	16	8	2.12 (0.90–5.0)
Height †
< median	461	16	10	1.91 (0.85–4.3)	0.9
≥ median	474	25	15	1.86 (0.97–3.6)
Dietary vitamin E †
< median	467	15	15	1.30 (0.63–2.7)	0.2
≥ median	468	26	10	2.70 (1.30–5.6)
Dietary vitamin C †
< median	467	15	16	0.98 (0.48–2.0)	0.026
≥ median	468	26	9	3.48 (1.61–7.5)
Residual of fruit, vegetables, berries †
< median	467	19	15	1.53 (0.76–3.1)	0.6
≥ median	468	22	10	2.27 (1.06–4.9)
β-Carotene supplementation
No	476	23	12	2.20 (1.06–4.5)	0.7
Yes	459	18	13	1.62 (0.78–3.4)

* Proportional hazards regression model comparing participants who received vitamin E with those who did not. The regression models were adjusted for age, baseline smoking, intake of coffee and alcohol, BMI and employment. Participants with missing data on confounders (n = 119) are excluded from this table. The sizes of all compared intervention groups are the same within 25% accuracy. RR, risk ratio; CI, confidence interval.
† The medians for the light-weight group are: weight 57.0 kg; BMI 20.0 kg/m²; height 168 cm; dietary vitamin E intake 9.1 mg/day; dietary vitamin C intake 75.3 mg/day; residual of fruit, vegetable, and berry intake -2.9 g/day.

ISSN: 1475-2891