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 4 Heaviest participants (body-weight ≥ 100 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	1226	20	7	3.10 (1.30–7.4)
BMI †
< median	613	8	4	2.18 (0.64–7.4)	0.3
≥ median	613	12	3	4.66 (1.30–16.7)
Height †
< median	593	11	5	2.19 (0.75–6.3)	0.4
≥ median	633	9	2	5.50 (1.11–27.1)
Dietary vitamin E †
< median	613	11	4	3.00 (0.94–9.5)	0.9
≥ median	613	9	3	3.85 (0.93–15.9)
Dietary vitamin C †
< median	613	8	6	1.37 (0.46–4.0)	0.019
≥ median	613	12	1	14.5 (1.84–114.5)
Residual of fruit, vegetables, berries †
< median	613	12	4	3.55 (1.13–11.2)	0.8
≥ median	613	8	3	2.65 (0.69–10.1)
β-Carotene supplementation
No	622	10	3	3.23 (0.89–11.8)	0.9
Yes	604	10	4	3.90 (1.10–13.8)

* 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 = 102) are excluded from this table. The sizes of all compared intervention groups are the same within 15% accuracy. RR, risk ratio; CI, confidence interval.
† The medians for the high-weight group are: weight 106.0 kg; BMI 33.5 kg/m²; height 179 cm; dietary vitamin E intake 12.4 mg/day; dietary vitamin C intake 95.5 mg/day; residual of fruit, vegetable, and berry intake -4.8 g/day.

ISSN: 1475-2891