THE TAR REDUCTION STUDY - RANDOMIZED TRIAL OF THE EFFECT OF CIGARETTE TAR YIELD REDUCTION ON COMPENSATORY SMELTING

被引:28
作者
FROST, C
FULLERTON, FM
STEPHEN, AM
STONE, R
NICOLAIDESBOUMAN, A
DENSEM, J
WALD, NJ
SEMMENCE, A
机构
[1] ST BARTHOLOMEWS HOSP,COLL MED,WOLFSON INST PREVENT MED,DEPT ENVIRONM & PREVENT MED,LONDON EC1M 6BQ,ENGLAND
[2] CIVIL SERV MED ADVISERS OFF,EDINBURGH EH2 3NB,MIDLOTHIAN,SCOTLAND
关键词
SMOKING; LOW YIELD; COMPENSATION; TAR;
D O I
10.1136/thx.50.10.1038
中图分类号
R56 [呼吸系及胸部疾病];
学科分类号
摘要
Background - Observational and short term intervention studies have reported that smokers of low tar cigarettes inhale more deeply (that is, compensate) than those who smoke high tar cigarettes. To quantify this effect a long term randomised trial was conducted on the effects of switching to low tar cigarettes. Methods - The trial was carried out between April 1985 and March 1988 among cigarette smokers in the British Civil Service, measuring blood carboxyhaemoglobin (COHb) levels and serum cotinine levels as markers of tobacco smoke intake. Volunteers first switched to a cigarette brand yielding around 10% less tar than their usual brand to identify smokers able to change brand. The 434 subjects who successfully switched were then randomly allocated to one of three groups: (a) ''fast reduction'' group which changed to a brand of cigarettes with a tar yield of about half that of their usual brand; (b) ''slow reduction'' group which reduced to the same level in steps over several months; and (c) a control group which continued smoking cigarettes with a tar yield 10% lower than their usual brand. Results - Over the course of the trial cigarette consumption declined slightly in all three groups. In both the ''fast reduction'' and the ''slow reduction'' groups, intake of COHb and cotinine was reduced, though not to the same extent as the yield reduction. Comparison of the results before randomisation with those at the end of the trial showed that a reduction in carbon monoxide yield of 45% was associated with a decrease in carbon monoxide intake of 19% (95% confidence interval 14% to 24%) and that a reduction in nicotine yield of 40% was associated with an 11% (6% to 16%) reduction in nicotine intake, reflecting relative intakes of about 1.5 for both carbon monoxide and nicotine in the ''fast reduction'' group. Results were similar in the ''slow reduction'' group with a 42% reduction in carbon monoxide yield, a 16% (11% to 22%) reduction in carbon monoxide intake, a 37% reduction in nicotine yield, and a 6% (0% to 13%) reduction in nicotine intake. Estimates of compensation derived from these results were 65% for carbon monoxide, 79% for nicotine, and 62% for tar. Conclusions - Compensation, demonstrated when switching from a high tar cigarette to a low tar one, was incomplete. Advising people who have failed to give up smoking to switch to low tar cigarettes will reduce the intake of smoke constituents to a small extent. This would be expected to decrease their risk of smoking-related diseases, although by a smaller amount than would be achieved by giving up smoking altogether.
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页码:1038 / 1043
页数:6
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