Since DiFranza's criticism of the editorial by Ling et al.(1) concentrates mostly on criticism of the paper by Fichtenberg and Glantz, published in Pediatrics,(2) we are writing to respond to these criticisms separately. We recognize that this is unusual, since the standard procedure would have been for DiFranza to write Pediatrics after the paper was published there. DiFranza, however, chose to write Tobacco Control (based on a preprint we provided him as a courtesy), so we are responding here.

The premise of youth access programs is that if merchant compliance reaches a high enough level, it will reduce youth access to cigarettes and, therefore, youth smoking. The goal of the first part of our analysis was to see if, based on the available literature, there was a relationship between merchant compliance and youth smoking. Whether or not the laws were being enforced at the time and if so, in what manner, is irrelevant to this analysis. If youth access programs work because high merchant compliance leads to lower smoking, there should be an association between high merchant compliance rates and low youth smoking rates, regardless of what led to those rates of compliance. If an intervention designed to increase merchant compliance was successful, we should see high compliance rates and low smoking. If the intervention was not successful, because they did not include enforcement as DiFranza suggests, there we should see low compliance and low smoking. (Whether there is prosecution of merchants or not (3) is irrelevant to testing whether making it difficult for teens to purchase cigarettes affects teen smoking prevalence.) Both of these cases would contribute to our test of the hypothesis that increased merchant compliance was associated with reduced smoking. The data to not exhibit such an association (Figure 1a of Fichtenberg and Glantz(2)).

All youth access program measure merchant compliance through undercover sales attempts by underage youth as was done in the Bagott(4) study. If merchant compliance measured in this was is not an accurate reflection of youth access, then none of the studies of youth access that base their effectiveness on merchant compliance are valid. The goal of our analysis was not to determine if compliance is a good measure of youth access but rather to relate the most commonly used metric for measuring the effectiveness of youth access programs, namely merchant compliance, and to youth smoking rates.

DiFranza says that we should not include studies from England because the legal age to purchase cigarettes is 16. We see no reason why youths aged 14-15 would not be affected by laws limiting purchase of cigarettes to those 16 and older.

DiFranza objects to including data from Australia, because 46% of the students lived outside the enforcement area.(10) As discussed above, whether or not active enforcement was involved is irrelevant to our analysis of the association between merchant compliance with youth access laws and youth smoking prevalence. All that is important is that compliance and smoking was assessed in the same community. In this case the authors point out that for the follow-up survey, 46% of students in the intervention community – which was defined based on school location – did not live in the intervention area. They conclude that this would be a problem if these children bought cigarettes closer to home rather than to school. Since there was no residence information from the baseline survey it was not possible to limit the analysis to student living in the intervention area. Nevertheless, we chose to include the study in our analysis despite this limitation. It is important to note that the results of this study were consistent with the others.

There is no problem with combining studies of different design in a quantitative meta-analysis as long as all studies are measuring the same endpoint. (11,12) As was reported in the methods section of our paper, the quantitative meta-analysis only included controlled studies. DiFranza objects to combining studies because the ages of the youths, and the methods used to test compliance, differed. (14) While we agree that factors such as age and gender of the youths may impact measured merchant compliance, we did not expect this variability to mask the effect of youth access programs, if they actually affected youth smoking rates. The small number, 5, of controlled studies of youth access programs which reported youth smoking made it impossible to stratify according to the age of the youths used in the compliance checks.

DiFranza objected to our evaluation of the change in youth smoking prevalence as a function of change in merchant compliance on the grounds that it is necessary to obtain compliance rates above 90% to have an effect on youth smoking prevalence. (15) In addition to the fact that the data shows no empirical evidence to support the hypothesis of such a threshold (Figure 1A in Fichtenberg and Glantz (2), reproduced as Figure 1 in Ling, et. al(1)), our basic premise is that if youth access programs actually reduced youth smoking, higher compliance rates would be associated with lower youth smoking rates. We examined this hypothesis in three ways. First we compared compliance and smoking rates in all communities for which both variables were measured at the same time. Since this is an ecological analysis which does not take into account trends over time, we then examined the relationship between changes in compliance and changes in smoking in case what mattered was whether there was a reduction in sales to youth rather than the absolute level of compliance at one time (Figure 1B in Fichtenberg and Glantz (2)) The data presented in Figure 1A demonstrate that there is no threshold of effectiveness at 90% compliance. Smoking rates for communities with compliance above 90% vary between 19.4%and 32.5%, with a mean of 25.9%. In communities with compliance rates below 90%, smoking rates vary between 15.6% and 37.7% with a mean of 25.7%. There is no evidence of a threshold of effectiveness.

DiFranza suggested that we control for a wide variety of socioeconomic and demographic factors. Because "When this type of analysis has been performed on a community and state level of analysis, reductions in youth smoking have been observed. (16,17)" Given the small number of studies available, it was not possible to explore the effects of potential confounders such as other tobacco control policies, price of cigarettes, socio-economic status. Nonetheless, in our discussion we report the results of population based studies, including but not limited to, those referred to by DiFranza. Chaloupka and Pacula (17) in the study cited by DiFranza do indeed find that statewide enactment and enforcement of youth access laws associated with reduced youth smoking. However in another analysis (18), the same authors found that this effect was restricted to black teens. The study by Siegel et al. (16) does indeed find that the presence of youth access laws was associated with decreased smoking initiation rates, however they conclude that this decrease was not mediated by decreased access because youths reported no decreased in perceived access.

In the first part of our analysis (Figure 1A), we compared compliance and smoking in all communities for which there was information. Since we were not trying to assess the effects of interventions but rather to see if there is a relationship between compliance and smoking, we did not make a distinction between control and intervention communities, or between baseline and follow-up data. As DiFranza points out, this type of analysis does not take into account temporal trends or other potential confounders. In order to take these into account we performed a quantitative meta- analysis using only controlled studies (n=5). This analysis yielded a pooled effect of a 1.5% decrease in youth prevalence (95%CI: 6% decrease to 3% increase).

Tutt cited a paper by his group (20) that was not included in our meta-analysis because it was not listed in Medline or cited in any of the other papers we located. Adding his results to those we report, however, does not affect the conclusions of our analysis. The correlation between merchant compliance and 30 day teen smoking prevalence including these data is .042 (P=.799) compared with .116 (P=.486) reported in Figure 1A of our paper. (2) Likewise the correlation between change in merchant compliance and change in youth smoking is -.163 (P=.504) compared with .294 (P=.237) without it. Thus, including Tutt, et. al's data actually strengthens the conclusions in our paper.

It is time for enthusiasts for youth access interventions to recognize that while these interventions may have seemed like a good idea, they do not achieve their primary goal of reducing youth smoking. All that happens is that youth obtain their cigarettes from other sources.(21)

Caroline Fichtenberg, MS, Department of Edidemiology, Johns Hopkins School of Public Health, Baltimore, MD Stanton A. Glantz, PhD, Center for Tobacco Control Research and Education, University of California, San Francisco

References:

1. Ling PM, Landman A, Glantz SA. It is time to abandon youth access tobacco programmes. Tobacco Control 2002;11:3-6. 2. Fichtenberg CM, Glantz SA. Youth access interventions do not affect youth smoking. Pediatrics (In press). 3. Altman DG, Wheelis AY, McFarlane M, et al. The relationship between tobacco access and use among adolescents: A four community study. Soc. Sci. Med. 1999;48;759-775. 4. Baggot M, Jordan C, Wright C, Jarvis S. How easy is it for young people to obtain cigarettes and do test sales by trading standards have any effect? A survey of two schools in Gateshead. Child: Care, Health and Development 1998;24:2007-216. 5. Staff M, March L, Brnabic A, Hort K, Alcock J, Coles S, Baxter R. Can non-prosecutory enforcement of public health legislation reduce smoking among high school students? Aust N Z J Public Health 1998;22:332-335. 6. Rigotti NA, DiFranza JR, Chang YC, Tisdale T, Kemp B, Singer DE. The effect of enforcing tobacco sales laws on youth's access to tobacco and smoking behavior: A controlled trial. New Engl J Med 1997;337:1044-51. 7. DiFranza JR, Rigotti NA. Impediments to the enforcement of youth access laws at the community level. Tobacco Control 1999;8:152-155. 8. Altman DG, Foster V, Rasenick-Douss L, Tye JB. Reducing the illegal sale of cigarettes to minors. JAMA 1989;261:80-83. 9. Altman DG, Rasenick-Douss L, Foster V, Tye JB. Sustained effects of an educational program to reduce dales of cigarettes to minors. American Journal of Public Health 1991;81:891-893. 10. Staff M, March L, Brnabic A, Hort K, Alcock J, Coles S, Baxter R. Can non-prosecutory enforcement of public health legislation reduce smoking among high school students? Aust N Z J Public Health 1998;22:332-335. 11. O’Grady B, Asbridge M, Abernathy T. Analysis of factors related to illegal tobacco sales to young people in Ontario. Tobacco Control 1999;8:301-305. 12. Pettiti D. Meta-Analysis, Decision Analysis, and Cost Effectiveness Analysis. 2nd ed. New York, NY: Oxford University Press; 2000. 13. Stroup DF, Berlin JA, Morton SC. Meta-analysis of observational studies in epidemiology. JAMA 2000;283:2008-2012. 14. Teall AM, Graham MC. Youth access to tobacco in two communities. Journal of Nursing Scholarship 2001;33:175-178. 15. Levy D, Chaloupka F, Slater S. Expert opinions on optimal enforcement of minimum purchase age laws for tobacco. J Public Health Management Practice 2000.6:107-114. 16. Siegel M, Biener L, Rigotti N. The effect of local tobacco sales laws on adolescent smoking initiation. Preventive Medicine. 1999;29:334-342. 17. Chaloupka F, Pacula R. Limiting youth access to tobacco: the early impact of the Synar Amendment on youth smoking. Working paper: Department of Economics, University of Illinois at Chicago; 1998. 18. Chaloupka F, Pacula R. Sex and race differences in young people’s responsiveness to price and tobacco control policies. Tobacco Control 1999;8:373-77. 19. Glantz SA. Preventing tobacco use-the youth access trap. Am J Public Health. 1996;86:221-4. 20. Tutt D, Bauer L, Edwards C, Cook D. Reducing adolescent smoking rates: Maintaining high retail compliance results in substantial improvements. Health Promotion Journal of Australia 2000;10:20-24. 21. Jones SE, Sharp DJ, Husten CG, et al. Cigarette acquisition and proof of age among U.S. high school students who smoke. Tobacco Control 2002;11:20–5.

I disagree totally with Stan Glantz and his view that we abandon youth access efforts.

As usual in every argument there is truth on both sides. He is right in being concerned that this can be an easy way for tobacco companies to look good and that teens will attempt to substitute other social sources. But one of the main sources of such secondary supply is other minors purchasing and then selling on the 'blackmarket', and our experience has been that making the primary source more difficult has led to a doubling of the playground price - a good price deterrent.

However, he is wrong in applying his objections equally in all jurisdictions. Would he seriously suggest that I abandon a local level intervention that has been shown to work so well, reducing smoking among teenagers on the Central Coast of New South Wales by a third over six years (1)? There is no mention in the editorial of that work.

Why can't we have "smoke free workplaces and homes" (Australia has got legislation and campaigns), "taxes" (we've got far higher taxes than the U.S.), "media campaigns "(we've got those) and "secondhand smoke messages" (we've got those) PLUS youth access PLUS advertising and promotion restrictions ( the U.S. still has a long way to go there) PLUS good anti-litter laws PLUS Quit support PLUS whatever else will work?

Perhaps his conclusion should be that youth access doesn't work IF you haven't got a comprehensive approach to tobacco control and it is undermined by inaction on the enforcement aspects or by inaction on the other strategic fronts. It's certainly not sufficient by itself, but as I've shown here - it can be a very cheap way of creating non-smokers at one tenth the cost of Nicotine Replacement Therapy(2).

Douglas Tutt

1)Tutt D, Bauer L, Edwards C,Cook D. Reducing adolescent smoking rates. Maintaining high retail compliance results in substantial impovemnts. Health Promotion Journal of Australia 2000:10(1)20-24 2)Tutt D. Enforcing prohibition of tobacco sales to minors :an update. Proceedings of 13th Winter School in the Sun, Alcohol and Drug Foundation - Queensland, Brisbane, Australia 2000.