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Cotinine measurements to monitor smoking in pregnancy
- Dr. Graham F. Cope (29 March 2008)
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Identification, referral and treatment: We need more of all three to reduce smoking in pregnancy
- Dr Linda Bauld, Dr. David Tappin, Susan Macaskill, Douglas Eadie (19 April 2008)
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Dr. Graham F. Cope, Honorary Senior Research Fellow University of Birmingham
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I read with great interest the article by Carmel O’Gorman (BMJ 9 February 2008) and fully support her call for better data collection about smoking in pregnancy. My experience from research carried out over a number of years has also caused me to question the validity and quality of smoking-related data obtained by midwives. I have been able to collect biochemically validated smoking prevalence data in pregnant women by utilising a point-of-care urine test called SmokeScreen. This test, which detects cotinine and the other nicotine metabolites, allows any healthcare professional to obtain immediate data about smoking habit. Cotinine, regarded as the ‘Gold Standard’ for verification of smoking, has a half-life of about 18 hours, which means it monitors smoking over an approximate three day period, which is much longer than that for expired-air carbon monoxide (CO), which only detects smoking for a few hours. SmokeScreen has been used successfully; both to show how many pregnant women fail to disclose their smoking habit to their midwives and to provide information back to the mothers to improve their willingness to quit smoking. Research, carried out in two hospital antenatal clinics monitored smoking in all women attending their first or ‘booking’ visit (n=856). The women were interviewed a few minutes after they had completed their ‘history’ with the midwife. In the knowledge that they were to be tested for smoking the women provided us with accurate information about their smoking behaviour. When this was compared to the ‘official’ history, we found a 10% denial of tobacco use and a 44% significant under reporting of cigarette consumption (1). We followed up all those who had a positive test result and saw them again at 38 weeks gestation. The outcome of the intervention achieved a doubling of the quit rate of 16%, compared 8% in controls. Another project carried out by community midwives using SmokeScreen at the booking appointment supported these findings and found the rate of smoking to be an alarming 47%, much higher than the 17% officially reported for the same population. Furthermore, 75% of the midwives thought the test motivated the women to stop smoking, 67% felt the test enriched their anti-smoking intervention and over half thought the test should be introduced as a routine screen in the early stages of pregnancy(2). The immediacy and nature of the test result not only correctly identifies women who smoke, but provides a ‘tool’ to increase awareness and improves understanding and their interaction with the information provided(3). Very few smokers appreciate why to stop smoking is so important to their medical condition. Firstly, they are weary of constant bombardment of the general anti-smoking message, and ‘switch off’. Secondly, they don’t appreciate that the chemical they inhale from tobacco actually gets into their blood stream, and so to their developing foetus. This information coupled with personalised results throughout pregnancy allows smoking to be monitored on a regular basis, so reiterating the message and improves smoking cessation, especially in the last trimester of pregnancy. I therefore endorse the call for more accurate data collection about smoking in pregnancy with a greater reliance on biochemically verified information. CO monitoring is one possible approach, but it is prone to false positives from environmental sources and a short abstinence from smoking (e.g. over night) will give a negative result. The point-of-care test described allows for quick and simple cotinine monitoring, and on a urine sample that is routinely brought to clinic and so removing further patient involvement. It could also remove a problem that many midwives have, in not wanting to ask women whether they smoke. This may be because they feel helpless in supporting them to stop or concerned that this may damage their working relationship; with many avoiding the question altogether. Using a tool such as Smokescreen offers them a starting point and it can often act as a motivational tool, with the aim of achieving a negative result at the next time of testing. The midwives can also use the result to introduce the local stop smoking service. References 1. Cope GF, Nayyar P, Holder R. Feedback from a point-of-care test for nicotine intake to reduce smoking during pregnancy. Ann Clin Biochem 2003; 40: 674-679 2. Giles J, Taylor D, Cope GF. Incorporation of a point-of-care cotinine test into routine community care to reduce smoking in pregnancy – a pilot study. Eur Conf Tob or Health Basel Switzerland Oct 2007. 3. DiClemente CC, Marinilli AS, Singh M, Bellino LE. The role of feedback in the process of health behaviour change. Am J Health Behav 2001; 25: 217 -227. Competing interests: Dr Cope is the inventor of the SmokeScreen tests and is a director of GFC Diagnostics Ltd, (grahamcope@gfcdiagnostics.co.uk) the manufacturer and distributor of the test. Thanks to Jane Giles for her helpful comments on the manuscript. |
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Dr Linda Bauld, Reader University of Bath, Dr. David Tappin, Susan Macaskill, Douglas Eadie
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Smoking in pregnancy harms women and children, but many women find stopping extremely difficult and only a minority access effective treatment, of the kind offered by NHS stop smoking service, to help them quit. As Carmel O’Gorman rightly points out, one of the biggest barriers to improving the uptake of services is that we have poor quality information on the extent of the problem. We really don’t know how many women are smoking in pregnancy. This problem is not unique to England, which is the focus of O’Gorman’s article. We recently conducted an audit of smoking in pregnancy services in Scotland (funded by NHS Health Scotland) which suggests that north of the border there are also concerns about the quality of data and the extent of service provision and uptake(1). O’Gorman described how routine data collected by hospital trusts with maternity services in England is incomplete and inconsistent. The same is true in Scotland. Our audit found that smoking status was recorded as unknown in 6% of cases in Scotland. In 2005, this meant there were more than 2,600 pregnant women in Scotland whose smoking status was not known at maternity booking, removing an important opportunity for intervention. Of equal concern is the fact that a previous study, focusing on Glasgow, found that the proportion of ‘unknown’ cases was higher in disadvantaged areas, reaching 30% in one large maternity hospital(2). The problem of under-reporting that O’Gorman highlights is one aspect contributing to uncertainty about smoking rates in pregnancy. We know that some pregnant women, when asked, will not disclose whether they smoke or not. A previous study found that 20% of smokers mis-reported themselves as non-smokers when asked at maternity booking by their routine midwife, verified by serum cotinine estimation on residual routine pregnancy blood samples in 1994(3) . As O’Gorman points out, a debate is needed about introducing routine testing of saliva or urine samples for cotinine to improve the reliability of data on prevalence. A response to her article by Graham Cope highlights how this type of testing can be used and the results it achieves. However, routine CO monitoring, despite its limitations, can also help to improve the identification of smokers at low cost. In Glasgow, where routine CO monitoring has occurred since 2004, a recent study found that 27% of smokers provided false answers when asked to self-report their smoking status, compared with CO monitoring results at a cut off of 2ppm(4). Although the use of routine CO monitoring is increasing in maternity units across the UK, most units do not have this in place and the practice should be much more common. In addition to improving the quality of data on smoking in pregnancy, we also need to improve the quality, availability and uptake of specialist services to help women to quit. In Scotland we found that referral rates of identified smokers to stop smoking support varied from 16% -93% between units(1). This kind of variability is unacceptable and suggests we could do much more to help women to access effective treatment. Equivalent national data is not available in England, but as O’Gorman and others have suggested, the picture is also likely to be variable. The Department of Health is about to launch a consultation on the future of tobacco control in England. Policies to protect children and young people from second hand smoke and prevent smoking uptake are likely to be high on the agenda. However, there is a risk that the one of the most essential building blocks of protection and prevention – reducing smoking in pregnancy – may not get the attention it deserves. We should be doing much more to identify smoking in pregnancy, increase referral rates to treatment and ensure that good quality services are available and accessible, if we are to make more progress in this important area. Linda Bauld, Reader in Social Policy, University of Bath, David Tappin, Clinical Senior Lecturer in Child Health, University of Glasgow, Susan MacAskill, Senior Researcher, University of Stirling and The Open University, Douglas Eadie, Senior Researcher, University of Stirling and The Open University. References: 1. Macaskill, S, Bauld, L, Eadie, D and Tappin, D (2008) Mapping of smoking cessation support in pregnancy in Scotland, NHS Health Scotland, Edinburgh. 2. Bauld, L, Day, P and Judge, K. (in press) Off target: a critical review of setting goals for reducing health inequalities in the UK, International Journal of Health Services Research, accepted December 2007. 3. Ford RPK, Tappin DM, Schluter PJ, et al. (1997) Smoking during pregnancy: How reliable are maternal self-reports in New Zealand? Journal of Epidemiology and Community Health, 51: 246-251. 4. Usmani, Z, Craig, P, Shipton, D and Tappin, D (2008) Comparison of CO breath testing and women's self-reporting of smoking behaviour for identifying smoking during pregnancy, Substance Abuse Treatment Prevention and Policy, 3,4, http://www.substanceabusepolicy.com/content/3/1/4 Competing interests: None declared |
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