| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
LETTER |
Harold Pollack and Paula M. Lantz are with the Department of Health Management and Policy, University of Michigan School of Public Health, Ann Arbor. John G. Frohna is with the Departments of Pediatrics and Internal Medicine, University of Michigan Medical School, Ann Arbor.
Correspondence: Requests for reprints should be sent to Harold Pollack, PhD, University of Michigan School of Public Health, 109 Observatory Dr, Ann Arbor, MI 48109-2029 (e-mail: haroldp{at}umich.edu).
De Weerd and colleagues raise the important issue of validity of maternal self-reported smoking. Their contribution highlights existing findings that some pregnant women underreport their tobacco use.123 De Weerd et al. add to this literature by offering the interesting finding of underreports among women receiving preconception counseling.
A primary issue for researchers is the direction and magnitude of the bias that results from underreporting of tobacco use. In epidemiologic studies attempting to demonstrate the association between maternal smoking and poor birth outcomes, the likely overarching effect is one of attenuation bias, that is, an underestimation of the effect of tobacco use on birthweight and other pregnancy outcomes. This probably applies to our research regarding the impact of maternal smoking on adverse birth outcomes among singletons and twins.4
In intervention studies, researchers should be especially concerned that patterns of underreporting may depend on specific context and may also differ across study groups. For example, in an evaluation of a low-intensity intervention in public health clinics, Kendrick et al. found that self-reported quit rates were higher among pregnant women at intervention clinics than at control clinics, whereas cotinine-verified quit rates were not significantly different.2 Apparently, women who received the cessation intervention were more likely to underreport their tobacco use.
It is important that smoking cessation interventions be targeted at women before conception, during pregnancy, and during the postpartum period. In research studies regarding the effectiveness of programs and policies, biochemical validation of self-reported smoking behavior—although invasive and expensive—is necessary for accurate estimates of intervention effects.56 Studies of the impact of smoking cessation interventions on birthweight highlight the utility of such validation.7
Unfortunately, direct chemical testing is generally not feasible in epidemiologic studies that scrutinize the impact of smoking on rare outcomes. The particular analysis that de Weerd and colleagues discuss examines the cost-effectiveness of smoking cessation interventions to prevent sudden infant death syndrome.8 Given the syndrome's baseline incidence of less than 1.0 per 1000 live births, this type of analysis requires extremely large, vital statistics datasets to obtain adequate power. Developing techniques to scrutinize the impact of underreporting in such analyses, where direct biochemical data are unavailable, remains an important statistical challenge for researchers concerned with tobacco use.
References
1. Floyd RL, Rimer BK, Giovino GA, Mullen PD, Sullivan SE. A review of smoking in pregnancy: effects on pregnancy outcomes and cessation efforts. Annu Rev Public Health. 1993;13:379–411.
2.
Kendrick JS, Zahnise SC, Miller N, et al. Integrating smoking cessation into routine public prenatal care: the Smoking Cessation in Pregnancy Project. Am J Public Health. 1995;85:217–222.
3. Boyd NR, Windsor RA, Perkins LL, Lowe JB. Quality of measurement of smoking status by self-report and saliva cotinine among pregnant women. Matern Child Health J. 1998;2(2):77–83.[Medline]
4.
Pollack H, Lantz PM, Frohna JG. Maternal smoking and adverse birth outcomes among singletons and twins. Am J Public Health. 2000;90:395–400.
5. Weissfeld JL, Holloway JJ, Kirscht JP. Effect of deceptive self-reports of quitting on the results of treatment trials for smoking: a quantitative assessment. J Clin Epidemiol. 1989;42:235–243.
6.
Dietz PM, Adams MM, Kendrick JS, Mathis MP. Completeness of ascertainment of prenatal smoking using birth certificates and confidential questionnaires: variations by maternal attributes and infant birth weight. Am J Epidemiol. 1998;148:1048–1054.
7. Li CQ, Windsor RA, Perkins L, Goldenberg RL, Lowe JB. The impact on infant birth weight and gestational age of cotinine-validated smoking reduction during pregnancy. JAMA. 1993;269:1519–1524.[Abstract]
8.
Pollack, HA. Sudden infant death syndrome, maternal smoking during pregnancy, and the cost-effectiveness of smoking cessation intervention. Am J Public Health. 2001;91:432–436.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
