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Dive into the research topics where Olalekan A. Ayo-Yusuf is active.

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Featured researches published by Olalekan A. Ayo-Yusuf.


Tobacco Control | 2011

Global surveillance of oral tobacco products: total nicotine, unionised nicotine and tobacco-specific N-nitrosamines

Stephen B. Stanfill; Gregory N. Connolly; Liqin Zhang; Lily T. Jia; Jack E. Henningfield; Patricia Richter; Tameka S. Lawler; Olalekan A. Ayo-Yusuf; David L. Ashley; Clifford H. Watson

Objective Oral tobacco products contain nicotine and carcinogenic tobacco-specific N-nitrosamines (TSNAs) that can be absorbed through the oral mucosa. The aim of this study was to determine typical pH ranges and concentrations of total nicotine, unionised nicotine (the most readily absorbed form) and five TSNAs in selected oral tobacco products distributed globally. Methods A total of 53 oral tobacco products from 5 World Health Organisation (WHO) regions were analysed for total nicotine and TSNAs, including 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), using gas chromatography or liquid chromatography with mass spectrometric detection. Unionised nicotine concentrations were calculated using product pH and total nicotine concentrations. Fourier transform infrared spectroscopy was used to help categorise or characterise some products. Results Total nicotine content varied from 0.16 to 34.1 mg/g product, whereas, the calculated unionised nicotine ranged from 0.05 to 31.0 mg/g product; a 620-fold range of variation. Products ranged from pH 5.2 to 10.1, which translates to 0.2% to 99.1% of nicotine being in the unionised form. Some products have very high pH and correspondingly high unionised nicotine (eg, gul powder, chimó, toombak) and/or high TSNA (eg, toombak, zarda, khaini) concentrations. The concentrations of TSNAs spanned five orders of magnitude with concentrations of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) ranging from 4.5 to 516 000 ng/g product. Conclusions These data have important implications for risk assessment because they show that very different exposure risks may be posed through the use of these chemically diverse oral tobacco products. Because of the wide chemical variation, oral tobacco products should not be categorised together when considering the public health implications of their use.


Health Education & Behavior | 2014

The Effect of Exposure to Pro-Tobacco Advertising on Experimentation With Emerging Tobacco Products Among U.S. Adolescents:

Israel T. Agaku; Olalekan A. Ayo-Yusuf

Introduction. This study assessed the influence of exposure to pro-tobacco advertisements on experimentation with emerging tobacco products among U.S. adolescents aged ≥9 years, in Grades 6 to 12. Method. Data were obtained from the 2011 National Youth Tobacco Survey. Multivariate logistic regression was used to measure the association between experimentation with snus and e-cigarettes and exposure to pro-tobacco advertisements from three sources: over the Internet, in newspapers/magazines, and at retail stores. Results. After controlling for sociodemographic characteristics and current use of other tobacco products, the odds of experimenting with snus were 1.36 (95% confidence interval [CI] = 0.88-3.16), 2.03 (95% CI = 1.30-3.17), and 3.24 (95% CI = 2.07-5.07), among students exposed to one, two, or all three types of pro-tobacco advertisements, respectively, compared with those exposed to none. Similar results were obtained for e-cigarettes. Conclusion. Stronger restrictions on tobacco advertisements, in concert with increased tobacco taxes and warning about the dangers of tobacco, use may help reduce youth tobacco use.


Drug and Alcohol Dependence | 2014

Poly-tobacco use among adults in 44 countries during 2008-2012: Evidence for an integrative and comprehensive approach in tobacco control

Israel T. Agaku; Filippos T. Filippidis; Constantine I. Vardavas; Oluwakemi Odukoya; Ayodeji Awopegba; Olalekan A. Ayo-Yusuf; Gregory N. Connolly

INTRODUCTION The concurrent use of multiple tobacco products (i.e., poly-tobacco use) might hinder efforts to reduce overall tobacco use, particularly considering that use of some non-cigarette tobacco products may be popular in some regions due to social, cultural, or economic reasons. This study assessed poly-tobacco use patterns among persons aged ≥15 years old from 44 countries. METHODS Data from 44 countries in all six World Health Organization regions were obtained from the 2008 to 2012 Global Adult Tobacco Surveys (n=19 countries), and the Special Eurobarometer 385 (77.1) survey, 2012 (n=25 countries). Correlates of poly-tobacco use were assessed using multivariate logistic regression analyses (p<0.05). RESULTS Overall prevalence of poly-tobacco use ranged from 0.8% (Mexico) to 11.9% (Denmark). In 28 countries, 20% or more of current smokers of manufactured cigarettes concurrently used at least one other tobacco product and this proportion was highest in India (66.2%) and lowest in Argentina (4.4%). After adjusting for other factors, the likelihood of being a poly-tobacco user among all respondents was lower among females (aOR=0.09; 95% CI: 0.08-0.11), and among respondents from upper-middle-income (aOR=0.53, 95% CI: 0.43-0.66), and lower-middle-income countries (aOR=0.64; 95% CI: 0.51-0.81) compared to high-income countries. Increased likelihood of poly-tobacco use was observed among respondents from the South-East Asian region compared to those from the European region (aOR=1.58, 95% CI: 1.35-1.85), as well as among respondents aged ≥65 years (aOR=2.10; 95% CI: 1.73-2.54), compared to those aged <25 years. CONCLUSIONS The pattern of tobacco use varied widely, underscoring the need for intensified efforts towards implementing policies that address all tobacco products, not only manufactured cigarettes.


Tobacco Control | 2004

Nicotine delivery capabilities of smokeless tobacco products and implications for control of tobacco dependence in South Africa

Olalekan A. Ayo-Yusuf; T J P Swart; W B Pickworth

Objectives: Smokeless tobacco (SLT) use is popular among black South African women and children. The study sought to determine the nicotine delivery capability of popular industrialised and traditional SLT brands in South Africa, and to provide information for policy action by regulatory authorities. Design: Laboratory chemical analysis of four industrialised and one traditional SLT products commercially available, using previously published analytical methods. Potential for dependence was inferred from nicotine delivery capabilities determined by the percentage free base nicotine. Measurements: Moisture, pH, total nicotine, and percentage free base nicotine. Results: Total nicotine content was between 6–16 mg/g. The pH varied between 7–10 and this correlated with percentage free base nicotine, which ranged between 10–99%. The nicotine delivery capability of the traditional product was lower than that of the industrialised products except for the recently introduced portion bag snus, which had comparable total nicotine but the lowest pH and percentage free base nicotine. The most popular SLT brands showed the highest percentage free base nicotine ever reported for any industrialised SLT or cigarette brands. Small cans contained higher nicotine than the large cans of the same brand tested. Findings from the study support a potential for limited “product graduation” by users. Conclusions: South African SLT users are mostly exposed to potentially very highly addictive levels of nicotine that may favour tobacco dependence and its consequent health risks. The increasing use of SLT by women of childbearing age support the need for intensified policy action to control its use.


Pediatrics | 2013

Use of Conventional and Novel Smokeless Tobacco Products Among US Adolescents

Israel T. Agaku; Olalekan A. Ayo-Yusuf; Constantine I. Vardavas; Hillel R. Alpert; Gregory N. Connolly

OBJECTIVES: To assess the prevalence and correlates of use of conventional and novel smokeless tobacco products among a national sample of US middle and high school students. METHODS: Data from the 2011 National Youth Tobacco Survey were analyzed to determine national estimates of current use of conventional (“chewing tobacco”, “snuff,” or “dip”), novel (“snus” and “dissolvable tobacco products”), and any smokeless tobacco products (novel and/or conventional products) within the past 30 days. RESULTS: The overall prevalence of current use of any smokeless tobacco product was 5.6% (n = 960). Among all students, 5.0% used chewing tobacco, snuff, or dip; 1.9% used snus; and 0.3% used dissolvable tobacco products. Among users of any smokeless tobacco, 64.0% used only conventional products, 26.8% were concurrent users of novel plus conventional products, whereas 9.2% exclusively used novel products. Approximately 72.1% of current any smokeless tobacco users concurrently smoked combustible tobacco products, and only 40.1% expressed an intention to quit all tobacco use. Regression analyses indicated that peer (adjusted odds ratio [aOR]: 9.56; 95% confidence interval [CI]: 7.14–12.80) and household (aOR: 3.32; 95% CI: 2.23–4.95) smokeless tobacco use were associated with smokeless tobacco use, whereas believing that all forms of tobacco are harmful was protective (aOR: 0.55; 95% CI: 0.38–0.79). CONCLUSIONS: Conventional smokeless tobacco products remain the predominant form of smokeless tobacco use. Most users of novel smokeless tobacco products also concurrently smoked combustible tobacco products. Smokeless tobacco use was associated with lower perception of harm from all tobacco products and protobacco social influences, indicating the need to change youth perceptions about the use of all tobacco products and to engage pediatricians in tobacco use prevention and cessation interventions.


Journal of Adolescent Health | 2014

Predictors and Patterns of Cigarette and Smokeless Tobacco Use Among Adolescents in 32 Countries, 2007–2011

Israel T. Agaku; Olalekan A. Ayo-Yusuf; Constantine I. Vardavas; Gregory N. Connolly

PURPOSE This study compared data from 32 countries to assess predictors and patterns of cigarette and smokeless tobacco (SLT) use among students aged 13-15 years old. METHODS Data from the 2007-2008 Global Youth Tobacco Surveys were analyzed for students aged 13-15 years in 31 countries located in all six World Health Organization regions. In addition, the 2011 National Youth Tobacco Survey was analyzed for U.S. students aged 13-15 years. Country-specific prevalence of current smoking, current SLT use, and concurrent use patterns were assessed. RESULTS The national prevalence of current cigarette smoking among students aged 13-15 years ranged from 1.8% (Rwanda) to 32.9% (Latvia), whereas current SLT use ranged from 1.1% (Montenegro) to 14.4% (Lesotho). In the U.S. and most European countries surveyed, current smoking prevalence was significantly higher than SLT prevalence, in contrast to patterns observed in low- and middle-income countries. Also, in most of the surveyed countries outside of Europe and the United States, SLT use among girls was as common as their use of cigarettes, and not significantly different from use by boys. When compared with U.S. adolescents, the odds of SLT use were highest among African adolescents (adjusted odds ratio = 3.98; 95% CI: 2.19-7.24) followed by those in the Southeast Asian region (adjusted odds ratio = 2.76; 95% CI: 1.38-5.53). CONCLUSIONS Region-specific patterns of tobacco use were noticed. Furthermore, it is alarming that in several low- and middle-income countries, the prevalence of SLT use among females did not differ from that among males, suggesting the possibility of a future shared burden of disease between both males and females.


Tobacco Control | 2008

Association of snuff use with chronic bronchitis among South African women: implications for tobacco harm reduction

Olalekan A. Ayo-Yusuf; Priscilla Reddy; B W van den Borne

Objective: Nasal use of snuff is the predominant form of tobacco use among black South African women. This study examines the association between snuff use and chronic bronchitis (CB) among black South African women. Design: The study investigated a nationally representative sample of 4464 black South African women ⩾25 years old who participated in the 1998 South African Demographic and Health Survey. Data on participants’ tobacco use patterns, medical history and other relevant factors were obtained through an interviewer-administered questionnaire. Peak expiratory flow rates (PEFR) were also measured. Data analysis included χ2 statistics, Student t tests and multiple logistic regression analysis. Outcome measure: CB, defined as reporting a productive cough for ⩾3 months/year for at least 2 successive years. Results: The prevalence of current snuff use was 16.1% (n = 719). Compared to non-users of snuff, snuff users were not only more likely to present with a history of tuberculosis (TB) (23.3% vs 15.9%; p = 0.06), but they were also more likely to present with CB (5.3% vs 2.8%; p<0.01) and a lower PEFR (275 litres/min vs 293 litres/min; p<0.01). Significant determinants of CB included snuff use >8 times/day (odds ratio (OR) 2.86, 95% CI 1.17 to 7.02), a history of TB (OR 7.23, 95% CI 4.02 to 13.03), current smoking (OR 2.84, 95% CI 1.60 to 5.04) and exposure to smoky cooking fuels (OR 1.98, 95% CI 1.32 to 2.96). Conclusions: These data suggest that snuff use, in the form predominantly used in South Africa, increases the risk of CB. This challenges the idea that snuff may be a much less harmful alternative to smoking in South Africa.


BMC Public Health | 2013

Tobacco use patterns in tuberculosis patients with high rates of human immunodeficiency virus co-infection in South Africa

Goedele M. C. Louwagie; Olalekan A. Ayo-Yusuf

BackgroundTuberculosis (TB) patients who smoke tobacco are at an increased risk for adverse TB treatment outcomes. This study describes tobacco use patterns among newly diagnosed TB patients, their readiness to quit, and their beliefs about tobacco-related health effects in a high HIV-burden setting in South Africa. Socio-economic and demographic factors associated with smoking were also determined.MethodsThis was a cross-sectional analysis of baseline data collected for a smoking cessation study at six large tuberculosis clinics in a South African township (N = 1926). We collected information on current and past tobacco use, socio-economic and demographic status, beliefs regarding the harmful effects of smoking and quit behaviour, and motivation, using structured interviewer-administered questionnaires. TB- and HIV-related information was obtained from patient records. Data analysis entailed descriptive statistics, followed by multivariate logistic regression with backward elimination, adjusted for clustering by facility.ResultsJust over one fifth of respondents (21.8%, 420/1924) reported currently smoking tobacco (males 37.6%, females 4.6%). By contrast, only 1.8% (35/1918) of all respondents reported being past smokers. Of the current smokers, about half (51.8%, 211/407) had previously attempted to quit, mainly for health reasons. The majority of respondents (89.3%, 1675/1875) believed tobacco smoking was harmful for their health and smokers were highly motivated to quit (median score 9, interquartile range 7–10). Smoking was less common among female respondents (Odds Ratio [OR] 0.10, 95% Confidence Interval [CI] 0.06-0.19) and respondents who had completed high school (OR 0.57, 95% CI 0.39-0.84), but was more common among respondents who do occasional work (OR 2.82, 95% CI 1.58-5.02), respondents who to bed hungry regularly (OR 4.19, 95% CI 2.42-7.25), those who have an alcohol problem (OR 5.79, 95% CI 3.24-10.34) and those who use illicit substances (OR 10.81, 95% CI 4.62-25.3).ConclusionsDespite documented evidence of its harmful effects, smoking is prevalent among male TB patients in this high HIV-prevalence population. Few patients have managed to quit smoking on their own. However, patients are highly motivated to stop smoking. We recommend implementing and evaluating a smoking cessation programme in tandem with TB services.


Tobacco Control | 2012

The complexity of ‘harm reduction’ with smokeless tobacco as an approach to tobacco control in low-income and middle-income countries

Olalekan A. Ayo-Yusuf; David M. Burns

Objective To review the implications of recommending smokeless tobacco (ST) use as a harm reduction approach for low-income and middle-income countries (LMICs). Method Narrative review of published papers and other data sources (including conference abstracts and internet-based information) on the health risks posed by the use of ST products for individual smokers and for the population with a focus on their implications for LMICs. Results Swedish snus has a relatively lower toxicity profile than ST products available in other markets, including older products used in the US and products used in Africa and Asia. The experience with snus in Sweden provides information on the effects of snus use in a population where cigarette smoking was already culturally ingrained. However, population effects are likely to be different in those LMICs where smoking is not yet the dominant culturally accepted form of tobacco use. The total effect may be negative in countries where locally-popular ST products have substantially higher disease risks than Swedish snus and where there is limited regulatory and tobacco use surveillance capacity. Conclusions Issues relating to how populations in LMICs respond to marketing efforts, the risks of the dual use of ST and smoking, and the capacity to regulate ST products need to be considered in making decisions about harm reduction strategies in LMICs. The public health effects of supporting ST as a harm reduction strategy may vary substantively in countries with different pre-existing tobacco use patterns.


South African Medical Journal | 2008

Association of tooth loss with hypertension

Olalekan A. Ayo-Yusuf; Imade J. Ayo-Yusuf

OBJECTIVE Hypertension may result from changes in dietary quality and nutrient intake. We therefore sought to determine the epidemiological association between tooth loss and hypertension in South African adults. METHODS This is a secondary data analysis of a cross-sectional survey of a nationally representative sample of adults aged 25 - 70 years who participated in the South African Demographic and Health Survey during 1998 (N = 9 098). The primary data were collected using a validated questionnaire, which included information on past experience of tooth loss (partial or complete), use of dental services, tobacco use and other known risk factors for hypertension. Hypertension was defined as having a measured average blood pressure (BP) > or = 160/95 mmHg and/or taking antihypertensive medication. RESULTS The prevalences of hypertension, any tooth loss and complete edentulousness were 18.1%, 72.2% and 9.4% respectively. Tooth loss was more common among overweight/obese respondents than among those with a normal body mass index (76.7% v. 66.7%; p < 0.01). Compared with the fully dentate respondents, the completely edentulous respondents had mean systolic and diastolic BPs that were respectively 12 mmHg and 5 mmHg higher. After adjusting for known risk factors for hypertension in a multiple logistic regression model, being completely edentulous remained significantly associated with hypertension (odds ratio 1.35, 95% confidence interval 1.02 - 1.78). The estimated population-attributable fraction of hypertension resulting from complete edentulousness was 10%. CONCLUSIONS The findings suggest that complete edentulousness is a risk indicator for hypertension in South Africa and highlights the importance of primary care practitioner involvement in oral health promotion.

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Israel T. Agaku

Centers for Disease Control and Prevention

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Priscilla Reddy

Human Sciences Research Council

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Olufemi B. Omole

University of the Witwatersrand

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