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Traffic Injury Prevention Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gcpi20
Association Between Travel Length and Drug Use Among Brazilian Truck Drivers a
a
a
Daniele Mayumi Sinagawa , Heráclito Barbosa De Carvalho , Gabriel Andreuccetti , Natanael b
b
c
Vitoriano Do Prado , Keziah Cristina Barbosa Gruber De Oliveira , Mauricio Yonamine , Daniel a
d
a
Romero Muñoz , Hallvard Gjerde & Vilma Leyton a
Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil
b
Department of Federal Highway Police, Sao Paulo, Brazil
c
Faculty of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, Brazil
d
Norwegian Institute of Public Health, Oslo, Norway Accepted author version posted online: 03 Apr 2014.Published online: 26 Sep 2014.
Click for updates To cite this article: Daniele Mayumi Sinagawa, Heráclito Barbosa De Carvalho, Gabriel Andreuccetti, Natanael Vitoriano Do Prado, Keziah Cristina Barbosa Gruber De Oliveira, Mauricio Yonamine, Daniel Romero Muñoz, Hallvard Gjerde & Vilma Leyton (2015) Association Between Travel Length and Drug Use Among Brazilian Truck Drivers, Traffic Injury Prevention, 16:1, 5-9, DOI: 10.1080/15389588.2014.906589 To link to this article: http://dx.doi.org/10.1080/15389588.2014.906589
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Traffic Injury Prevention (2015) 16, 5–9 C Taylor & Francis Group, LLC Copyright ISSN: 1538-9588 print / 1538-957X online DOI: 10.1080/15389588.2014.906589
Association Between Travel Length and Drug Use Among Brazilian Truck Drivers ´ DANIELE MAYUMI SINAGAWA1, HERACLITO BARBOSA DE CARVALHO1, GABRIEL ANDREUCCETTI1, 2 NATANAEL VITORIANO DO PRADO , KEZIAH CRISTINA BARBOSA GRUBER DE OLIVEIRA2, 1 ˜ , HALLVARD GJERDE4, and VILMA LEYTON1 MAURICIO YONAMINE3, DANIEL ROMERO MUNOZ 1
Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil Department of Federal Highway Police, Sao Paulo, Brazil 3 Faculty of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, Brazil 4 Norwegian Institute of Public Health, Oslo, Norway
Downloaded by [The University of Texas at El Paso] at 19:42 07 November 2014
2
Received 17 January 2014, Accepted 18 March 2014
Objective: To investigate whether the use of the stimulants amphetamines and cocaine by truck drivers in Brazil was related to travel length. Methods: Truck drivers were randomly stopped by the Federal Highway Police on interstate roads in Sao Paulo State during ´ nas Rodovias” (Health Commands morning hours from 2008 to 2011 and invited to participate in the project “Comandos de Saude on the Roads). Participants were asked about the use of drugs, travel distance, and age, and gender was recorded. Samples of urine were collected and analyzed for amphetamine, benzoylecgonine (a metabolite of cocaine), and carboxytetrahydrocannabinol (THC-COOH; a metabolite of cannabis) by immunological screening and quantification by gas chromatography–mass spectroscopy. Results: Current use of amphetamine, cocaine, and cannabis was reported by 5.7%, 0.7%, and 0.3% of the truck drivers, respectively. Amphetamine, benzoylecgonine, and THC-COOH were found in urine samples from 5.4%, 2.6,% and in 1.0% of the drivers, respectively. There was a significant association between the positive cases for amphetamine and reported travel length; 9.9% of urine samples from drivers who reported travel length of more than 270 km were positive for amphetamine, and 10.9% of those drivers reported current use of amphetamines. In most cases, appetite suppressants containing amphetamines had been used, but the purpose was most often to stay awake and alert while driving. Truck drivers with travel length of more than 270 km had significantly higher odds ratio (OR) for having a urine sample that was positive for amphetamine when adjusted for age as confounding factor (OR = 9.41, 95% confidence interval [CI], 3.97–22.26). No significant association was found between the use of cocaine or cannabis and travel length. Conclusion: Truck drivers who reported driving more than 270 km had significantly higher frequencies of urine samples positive for amphetamine and reported significantly more frequent current use of amphetamines than those who reported shorter driving distances. Keywords: trucks, drugs, toxicology, driver behavior
Introduction Freight transportation in Brazil is predominantly carried out by trucks on the highways, which comprise a network of about 1.7 million km; only about 16% is paved. Many truck drivers drive long distances, often during the night and with little resting time, in order to obtain a good monthly income. A study published in 2010 found that 28% of drivers drove more than 10 hours per day and 60% worked partly at night (Ulhoa et al. 2010). Managing Editor David Viano oversaw the review of this article Address correspondence to Daniele Mayumi Sinagawa. Faculty of Medicine, University of Sao Paulo, Oscar Freire Institute, 455, Doutor Arnaldo Avenue, Sao Paulo/SP 01246–903, Brazil. Email: [email protected]
Many road traffic crashes are related to drowsiness, sleepiness, or fatigue (Robb et al. 2008). In addition to long driving hours, important contributors to fatigue among truck drivers are insufficient nighttime sleep and insufficient rest breaks (Friswell and Williamson 2008; Noce et al. 2008). One study found that 40% of Brazilian truck drivers reported sleeping less than 5 h per day and 46% reported hypersomnolence (Pinho et al. 2006). Therefore, many Brazilian truck drivers may have increased risk for involvement in traffic crashes. Trucks are involved in about 26% of all traffic crashes in Brazil (DENATRAN 2006). In a study of 300 Brazilian truck drivers, 34% reported that they had been involved in a traffic crash in the past (Pinho et al. 2006); in another study, 11% of 439 truck drivers reported involvement in a crash during the last 12 months (Ulhoa et al. 2010). Drivers reported that about 27% of the crashes were due to sleepiness (Pinho et al. 2006).
Downloaded by [The University of Texas at El Paso] at 19:42 07 November 2014
6 Sometimes truck drivers drive for many days in a row. Instead of taking breaks and sufficient periods of sleep, some truck drivers use amphetamines to combat the detrimental effects of fatigue. One of the most commonly taken drugs of this type used to be fenproporex (Wendler et al. 2003; Zancanaro et al. 2012), which was sold as an appetite suppressant without prescription until it was withdrawn from the market in December 2011; this drug is metabolized to amphetamine (Comiran et al. 2012). Cocaine, which also is a stimulating drug, may be used for the same purpose (Burns 1993; Stillman et al. 1993). A study of 91 truck drivers in southeastern Brazil performed in 2005 found that 66% of long-distance truck drivers reported using amphetamines during their travels, purchased mainly at petrol stations along the highways (Nascimento et al. 2007); a larger survey in 2006 of 854 truck drivers found that 12.1% reported the use of amphetamines (Knauth et al. 2012). In studies analyzing urine samples collected from truck drivers during 2003–2009, 4.8–10.8% were found to be positive for amphetamines (Leyton et al. 2012; Silva et al. 2003; Takitane et al. 2013). Some studies also investigated the use of cocaine and cannabis; the cocaine metabolite benzoylecgonine was detected in 0.3–2.2% of the urine samples, and the cannabis metabolite THC-COOH was detected in 0.3–1.1% of the samples (Leyton et al. 2012; Silva et al. 2003). After the withdrawal of legal amphetamines from the market, some truck drivers still used amphetamines. A study of 427 truck drivers performed in 2012 found that 2.7% of urine samples were positive for amphetamines (Oliveira et al. 2013). Despite the fact that drivers may feel more alert after taking amphetamines and also perform better on some psychomotor tests (Caldwell et al. 2003; Kelly et al. 1991), this may not always improve driving ability (Hj¨almdahl et al. 2012; Silber et al. 2005). A Norwegian study found that amphetamine or methamphetamine was found in 8.9% of blood samples from drivers killed in road crashes, whereas only about 0.2% of drivers in random traffic were positive for those drugs (Gjerde et al. 2013), indicating a strong association between the use of amphetamines and fatal accidents. The use of amphetamines has also been found to be associated with road traffic crashes in other studies (Bernhoft et al. 2012; Gates et al. 2013). Driving hour regulations implemented in the United States (Federal Motor Carrier Safety Administration 2011), Europe (European Union 2006), Australia (National Transport Commission 2008), and other countries eliminate the very long driving periods that might tempt the drivers to use illegal stimulants to stay awake. New working time regulations were approved by the Brazilian parliament in July 2012. The goal of these new regulations was to reduce driver fatigue and the number of accidents caused by excessive hours behind the wheel. The main hours-of-service rules require that drivers rest at least 30 min every 4 h, nighttime rest should be a minimum of 11 h, and the driving limit is 10 h during 13 consecutive hours. However, the enforcement of these regulations did not appear to be completely implemented at the time this article was written. Because drowsiness and sleepiness are related to the length of the driving period, one might expect that the use of stimulant drugs would also be associated with the number of driving
Sinagawa et al. hours or length of travel. The aim of this study was to investigate this hypothesis among Brazilian truck drivers.
Methods Study Design and Setting Truck drivers were randomly stopped by the Federal Highway Police on interstate roads in Sao Paulo State between 9 a.m. and 2 p.m. on selected days during 2008–2011 using a 3-stage cluster sampling procedure. In the first stage, the road sites were selected; in the second stage, the dates for the study were chosen; and in the third stage, between 100 and 150 random drivers of trucks weighing more than about 30 tons were in´ nas vited to participate in the project “Comandos de Saude Rodovias” (Health Commands on the Roads), which provided free health services to truck drivers. This was not part of a police control of truck drivers. The police were asked to stop random trucks according to the availability of parking spaces and the handling capacity of the health personnel. The project team provided information about health issues and performed medical examinations, which took up to 45 min. In addition to medical examinations, the drivers were asked to participate in an anonymous and voluntary research project on the use of drugs by providing a urine sample for drug testing in addition to answering questions on their current journey. Interviews and Sample Collection The interviews were carried out face to face (Catania et al. 1990), and participants signed an informed consent form. Age, gender, education, and marital status were recorded in addition to information about the place of departure, destination, and travel length. The drivers were asked whether they used amphetamines, cocaine, or cannabis (options: “yes,” “no,” or “previously”) and the reason for use (options: “to stay awake” or “other reason; in that case please specify”). Urine samples were collected in polyethylene bottles previously identified with a number linking the sample to the questionnaire. The samples collected were kept under refrigeration and transported to a laboratory during the day of collection where the samples were frozen at −20◦ C. A maximum of 6 days was allowed between collection and analysis of urine samples. Laboratory Analysis The samples were analyzed at the Faculty of Pharmacy of the University of Sao Paulo. Drug screening for amphetamines, cocaine metabolites, and cannabinoids was performed using immunoassays (Multi-Drug One Step Test, Inlab, Sao Paulo, Brazil). Positive screening results were confirmed by gas chromatography–mass spectrometry (Gustafson et al. 2003; Scheidweiler and Huestis 2006; Yonamine and Silva 2002) using Agilent 5890 and 5975 gas chromatography/mass selective detector systems (Agilent Technologies, Santa Clara, CA). The following cutoff values were used in
Association Between Travel Length and Drug Use the confirmation test: amphetamine/methamphetamine 500 ng/mL; delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) 15 ng/mL; benzoylecgonine 150 ng/mL.
7 Table 1. Drug findings in urine samples and self-reported drug use presented as prevalence (%) and number of positive findings (in parentheses) in relation to travel length ≤270 km (N = 507) 270 km (N = 486)
Downloaded by [The University of Texas at El Paso] at 19:42 07 November 2014
Statistical Analysis For the estimations of drug prevalence, Wilson’s binomial 95% confidence intervals (95% CI) were calculated incorporating continuity correction (Newcombe 1998; Wilson 1927). Possible differences between truck drivers with long and short travel lengths or between age groups were initially investigated using Pearson’s chi-square test for categorical data. Possible differences in substance use were also investigated with binary logistic regression using SPSS 20 statistical software (IBM Corporation, Armonk, NY). The drug finding was included as a dependent variable (with 2 categories, 0 = negative; 1 = positive), and travel length was used as a covariate (with 2 categories, 0 = ≤270 km; 1 = >270 km). The backward stepwise likelihood ratio method was used to determine which other covariates to include. The conventional critical 5% level was used to assess whether the obtained odds ratio (OR) significantly deviated from 1. The overall goodness-of-fit was assessed using the Hosmer-Lemeshow test (Hosmer and Lemeshow 2000).
Age (%) 270 km Age 270 km Age 270 km Age
Traffic Injury Prevention Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/gcpi20
Association Between Travel Length and Drug Use Among Brazilian Truck Drivers a
a
a
Daniele Mayumi Sinagawa , Heráclito Barbosa De Carvalho , Gabriel Andreuccetti , Natanael b
b
c
Vitoriano Do Prado , Keziah Cristina Barbosa Gruber De Oliveira , Mauricio Yonamine , Daniel a
d
a
Romero Muñoz , Hallvard Gjerde & Vilma Leyton a
Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil
b
Department of Federal Highway Police, Sao Paulo, Brazil
c
Faculty of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, Brazil
d
Norwegian Institute of Public Health, Oslo, Norway Accepted author version posted online: 03 Apr 2014.Published online: 26 Sep 2014.
Click for updates To cite this article: Daniele Mayumi Sinagawa, Heráclito Barbosa De Carvalho, Gabriel Andreuccetti, Natanael Vitoriano Do Prado, Keziah Cristina Barbosa Gruber De Oliveira, Mauricio Yonamine, Daniel Romero Muñoz, Hallvard Gjerde & Vilma Leyton (2015) Association Between Travel Length and Drug Use Among Brazilian Truck Drivers, Traffic Injury Prevention, 16:1, 5-9, DOI: 10.1080/15389588.2014.906589 To link to this article: http://dx.doi.org/10.1080/15389588.2014.906589
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Traffic Injury Prevention (2015) 16, 5–9 C Taylor & Francis Group, LLC Copyright ISSN: 1538-9588 print / 1538-957X online DOI: 10.1080/15389588.2014.906589
Association Between Travel Length and Drug Use Among Brazilian Truck Drivers ´ DANIELE MAYUMI SINAGAWA1, HERACLITO BARBOSA DE CARVALHO1, GABRIEL ANDREUCCETTI1, 2 NATANAEL VITORIANO DO PRADO , KEZIAH CRISTINA BARBOSA GRUBER DE OLIVEIRA2, 1 ˜ , HALLVARD GJERDE4, and VILMA LEYTON1 MAURICIO YONAMINE3, DANIEL ROMERO MUNOZ 1
Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil Department of Federal Highway Police, Sao Paulo, Brazil 3 Faculty of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, Brazil 4 Norwegian Institute of Public Health, Oslo, Norway
Downloaded by [The University of Texas at El Paso] at 19:42 07 November 2014
2
Received 17 January 2014, Accepted 18 March 2014
Objective: To investigate whether the use of the stimulants amphetamines and cocaine by truck drivers in Brazil was related to travel length. Methods: Truck drivers were randomly stopped by the Federal Highway Police on interstate roads in Sao Paulo State during ´ nas Rodovias” (Health Commands morning hours from 2008 to 2011 and invited to participate in the project “Comandos de Saude on the Roads). Participants were asked about the use of drugs, travel distance, and age, and gender was recorded. Samples of urine were collected and analyzed for amphetamine, benzoylecgonine (a metabolite of cocaine), and carboxytetrahydrocannabinol (THC-COOH; a metabolite of cannabis) by immunological screening and quantification by gas chromatography–mass spectroscopy. Results: Current use of amphetamine, cocaine, and cannabis was reported by 5.7%, 0.7%, and 0.3% of the truck drivers, respectively. Amphetamine, benzoylecgonine, and THC-COOH were found in urine samples from 5.4%, 2.6,% and in 1.0% of the drivers, respectively. There was a significant association between the positive cases for amphetamine and reported travel length; 9.9% of urine samples from drivers who reported travel length of more than 270 km were positive for amphetamine, and 10.9% of those drivers reported current use of amphetamines. In most cases, appetite suppressants containing amphetamines had been used, but the purpose was most often to stay awake and alert while driving. Truck drivers with travel length of more than 270 km had significantly higher odds ratio (OR) for having a urine sample that was positive for amphetamine when adjusted for age as confounding factor (OR = 9.41, 95% confidence interval [CI], 3.97–22.26). No significant association was found between the use of cocaine or cannabis and travel length. Conclusion: Truck drivers who reported driving more than 270 km had significantly higher frequencies of urine samples positive for amphetamine and reported significantly more frequent current use of amphetamines than those who reported shorter driving distances. Keywords: trucks, drugs, toxicology, driver behavior
Introduction Freight transportation in Brazil is predominantly carried out by trucks on the highways, which comprise a network of about 1.7 million km; only about 16% is paved. Many truck drivers drive long distances, often during the night and with little resting time, in order to obtain a good monthly income. A study published in 2010 found that 28% of drivers drove more than 10 hours per day and 60% worked partly at night (Ulhoa et al. 2010). Managing Editor David Viano oversaw the review of this article Address correspondence to Daniele Mayumi Sinagawa. Faculty of Medicine, University of Sao Paulo, Oscar Freire Institute, 455, Doutor Arnaldo Avenue, Sao Paulo/SP 01246–903, Brazil. Email: [email protected]
Many road traffic crashes are related to drowsiness, sleepiness, or fatigue (Robb et al. 2008). In addition to long driving hours, important contributors to fatigue among truck drivers are insufficient nighttime sleep and insufficient rest breaks (Friswell and Williamson 2008; Noce et al. 2008). One study found that 40% of Brazilian truck drivers reported sleeping less than 5 h per day and 46% reported hypersomnolence (Pinho et al. 2006). Therefore, many Brazilian truck drivers may have increased risk for involvement in traffic crashes. Trucks are involved in about 26% of all traffic crashes in Brazil (DENATRAN 2006). In a study of 300 Brazilian truck drivers, 34% reported that they had been involved in a traffic crash in the past (Pinho et al. 2006); in another study, 11% of 439 truck drivers reported involvement in a crash during the last 12 months (Ulhoa et al. 2010). Drivers reported that about 27% of the crashes were due to sleepiness (Pinho et al. 2006).
Downloaded by [The University of Texas at El Paso] at 19:42 07 November 2014
6 Sometimes truck drivers drive for many days in a row. Instead of taking breaks and sufficient periods of sleep, some truck drivers use amphetamines to combat the detrimental effects of fatigue. One of the most commonly taken drugs of this type used to be fenproporex (Wendler et al. 2003; Zancanaro et al. 2012), which was sold as an appetite suppressant without prescription until it was withdrawn from the market in December 2011; this drug is metabolized to amphetamine (Comiran et al. 2012). Cocaine, which also is a stimulating drug, may be used for the same purpose (Burns 1993; Stillman et al. 1993). A study of 91 truck drivers in southeastern Brazil performed in 2005 found that 66% of long-distance truck drivers reported using amphetamines during their travels, purchased mainly at petrol stations along the highways (Nascimento et al. 2007); a larger survey in 2006 of 854 truck drivers found that 12.1% reported the use of amphetamines (Knauth et al. 2012). In studies analyzing urine samples collected from truck drivers during 2003–2009, 4.8–10.8% were found to be positive for amphetamines (Leyton et al. 2012; Silva et al. 2003; Takitane et al. 2013). Some studies also investigated the use of cocaine and cannabis; the cocaine metabolite benzoylecgonine was detected in 0.3–2.2% of the urine samples, and the cannabis metabolite THC-COOH was detected in 0.3–1.1% of the samples (Leyton et al. 2012; Silva et al. 2003). After the withdrawal of legal amphetamines from the market, some truck drivers still used amphetamines. A study of 427 truck drivers performed in 2012 found that 2.7% of urine samples were positive for amphetamines (Oliveira et al. 2013). Despite the fact that drivers may feel more alert after taking amphetamines and also perform better on some psychomotor tests (Caldwell et al. 2003; Kelly et al. 1991), this may not always improve driving ability (Hj¨almdahl et al. 2012; Silber et al. 2005). A Norwegian study found that amphetamine or methamphetamine was found in 8.9% of blood samples from drivers killed in road crashes, whereas only about 0.2% of drivers in random traffic were positive for those drugs (Gjerde et al. 2013), indicating a strong association between the use of amphetamines and fatal accidents. The use of amphetamines has also been found to be associated with road traffic crashes in other studies (Bernhoft et al. 2012; Gates et al. 2013). Driving hour regulations implemented in the United States (Federal Motor Carrier Safety Administration 2011), Europe (European Union 2006), Australia (National Transport Commission 2008), and other countries eliminate the very long driving periods that might tempt the drivers to use illegal stimulants to stay awake. New working time regulations were approved by the Brazilian parliament in July 2012. The goal of these new regulations was to reduce driver fatigue and the number of accidents caused by excessive hours behind the wheel. The main hours-of-service rules require that drivers rest at least 30 min every 4 h, nighttime rest should be a minimum of 11 h, and the driving limit is 10 h during 13 consecutive hours. However, the enforcement of these regulations did not appear to be completely implemented at the time this article was written. Because drowsiness and sleepiness are related to the length of the driving period, one might expect that the use of stimulant drugs would also be associated with the number of driving
Sinagawa et al. hours or length of travel. The aim of this study was to investigate this hypothesis among Brazilian truck drivers.
Methods Study Design and Setting Truck drivers were randomly stopped by the Federal Highway Police on interstate roads in Sao Paulo State between 9 a.m. and 2 p.m. on selected days during 2008–2011 using a 3-stage cluster sampling procedure. In the first stage, the road sites were selected; in the second stage, the dates for the study were chosen; and in the third stage, between 100 and 150 random drivers of trucks weighing more than about 30 tons were in´ nas vited to participate in the project “Comandos de Saude Rodovias” (Health Commands on the Roads), which provided free health services to truck drivers. This was not part of a police control of truck drivers. The police were asked to stop random trucks according to the availability of parking spaces and the handling capacity of the health personnel. The project team provided information about health issues and performed medical examinations, which took up to 45 min. In addition to medical examinations, the drivers were asked to participate in an anonymous and voluntary research project on the use of drugs by providing a urine sample for drug testing in addition to answering questions on their current journey. Interviews and Sample Collection The interviews were carried out face to face (Catania et al. 1990), and participants signed an informed consent form. Age, gender, education, and marital status were recorded in addition to information about the place of departure, destination, and travel length. The drivers were asked whether they used amphetamines, cocaine, or cannabis (options: “yes,” “no,” or “previously”) and the reason for use (options: “to stay awake” or “other reason; in that case please specify”). Urine samples were collected in polyethylene bottles previously identified with a number linking the sample to the questionnaire. The samples collected were kept under refrigeration and transported to a laboratory during the day of collection where the samples were frozen at −20◦ C. A maximum of 6 days was allowed between collection and analysis of urine samples. Laboratory Analysis The samples were analyzed at the Faculty of Pharmacy of the University of Sao Paulo. Drug screening for amphetamines, cocaine metabolites, and cannabinoids was performed using immunoassays (Multi-Drug One Step Test, Inlab, Sao Paulo, Brazil). Positive screening results were confirmed by gas chromatography–mass spectrometry (Gustafson et al. 2003; Scheidweiler and Huestis 2006; Yonamine and Silva 2002) using Agilent 5890 and 5975 gas chromatography/mass selective detector systems (Agilent Technologies, Santa Clara, CA). The following cutoff values were used in
Association Between Travel Length and Drug Use the confirmation test: amphetamine/methamphetamine 500 ng/mL; delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) 15 ng/mL; benzoylecgonine 150 ng/mL.
7 Table 1. Drug findings in urine samples and self-reported drug use presented as prevalence (%) and number of positive findings (in parentheses) in relation to travel length ≤270 km (N = 507) 270 km (N = 486)
Downloaded by [The University of Texas at El Paso] at 19:42 07 November 2014
Statistical Analysis For the estimations of drug prevalence, Wilson’s binomial 95% confidence intervals (95% CI) were calculated incorporating continuity correction (Newcombe 1998; Wilson 1927). Possible differences between truck drivers with long and short travel lengths or between age groups were initially investigated using Pearson’s chi-square test for categorical data. Possible differences in substance use were also investigated with binary logistic regression using SPSS 20 statistical software (IBM Corporation, Armonk, NY). The drug finding was included as a dependent variable (with 2 categories, 0 = negative; 1 = positive), and travel length was used as a covariate (with 2 categories, 0 = ≤270 km; 1 = >270 km). The backward stepwise likelihood ratio method was used to determine which other covariates to include. The conventional critical 5% level was used to assess whether the obtained odds ratio (OR) significantly deviated from 1. The overall goodness-of-fit was assessed using the Hosmer-Lemeshow test (Hosmer and Lemeshow 2000).
Age (%) 270 km Age 270 km Age 270 km Age
