Concurrent crack and powder cocaine users from Sao Paulo: Do they represent a different group?

Abstract

Cocaine abuse is a serious and socially damaging illegal drug problem. Different routes of administration are associated with a specific progression of use, different degrees of abuse liability, propensity for dependence and treatment response. There have been relatively few studies comparing different cocaine users groups and no studies into the characterization of the group of individuals reporting concurrent use of powder cocaine and crack cocaine.
Six hundred and ninety-nine cocaine users were assessed during the period August 1997 to October 1998 in one outpatient and six inpatient clinics located in the São Paulo, Brazil. Patients were interviewed using a structured questionnaire schedule in Portuguese, designed specifically for the Brazilian population. The statistical analyses were performed using either ANOVA or a chi-squared test and focusing on their preferred form of use/route of administration and other variables.
For 83% of the variables tested in this study, the Dual Users subgroup (using both powder and crack cocaine) demonstrated statistical differences from the single drug user subgroups. Those differences include the initiation of cocaine, the abuse of other illicit drugs, and rates of criminal history.
These data suggest cocaine-dependent individuals who report use of both powder and crack cocaine are an at least partially, distinct subgroup. However, further studies will be necessary to confirm this and to determine if they also show a different treatment response.

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BMC Public Health
Open Access
Research article
Concurrent crack and powder cocaine users from Sao Paulo: Do
they represent a different group?
Camila Guindalini
1,2
, Homero Vallada
1
, Gerome Breen*
2
and
Ronaldo Laranjeira
3
Address:
1
Department of Psychiatry, University of São Paulo Medical School, Brazil,
2
MRC Social Genetic and Developmental Psychiatry Research
Centre, Institute of Psychiatry, King's College London, UK and
3
UNIAD (Unit of Drug and Alcohol Research), Department of Psychiatry, Federal
University of São Paulo, Brazil
Email: Camila Guindalini - c.guindalini@iop.kcl.ac.uk; Homero Vallada - hvallada@usp.br; Gerome Breen* - g.breen@iop.kcl.ac.uk;
Ronaldo Laranjeira - laranjeira@psiquiatria.epm.br
* Corresponding author
Abstract
Background: Cocaine abuse is a serious and socially damaging illegal drug problem. Different
routes of administration are associated with a specific progression of use, different degrees of abuse
liability, propensity for dependence and treatment response. There have been relatively few studies
comparing different cocaine users groups and no studies into the characterization of the group of
individuals reporting concurrent use of powder cocaine and crack cocaine.
Methods: Six hundred and ninety-nine cocaine users were assessed during the period August 1997
to October 1998 in one outpatient and six inpatient clinics located in the São Paulo, Brazil. Patients
were interviewed using a structured questionnaire schedule in Portuguese, designed specifically for
the Brazilian population. The statistical analyses were performed using either ANOVA or a chi-
squared test and focusing on their preferred form of use/route of administration and other
variables.
Results: For 83% of the variables tested in this study, the Dual Users subgroup (using both powder
and crack cocaine) demonstrated statistical differences from the single drug user subgroups. Those
differences include the initiation of cocaine, the abuse of other illicit drugs, and rates of criminal
history.
Conclusion: These data suggest cocaine-dependent individuals who report use of both powder
and crack cocaine are an at least partially, distinct subgroup. However, further studies will be
necessary to confirm this and to determine if they also show a different treatment response.
Background
Cocaine abuse is one of the most serious and socially
damaging illegal drug problems. The 2003 US National
Survey on Drug Use and Health [1] found that 14.7% of
the population of the United States aged 12 and older had
tried cocaine at least once in their lifetimes. In Europe, the
highest rate with a lifetime prevalence of 5.2% was
reported for the United Kingdom [2]. In Brazil it is esti-
mated that 10% of those aged 18–28 years in Sao Paulo
have used cocaine at least once [3]. However, it remains
Published: 20 January 2006
BMC Public Health 2006, 6:10 doi:10.1186/1471-2458-6-10
Received: 27 April 2005
Accepted: 20 January 2006
This article is available from: http://www.biomedcentral.com/1471-2458/6/10
© 2006 Guindalini et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0
),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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unclear how many current users there are, or how many
are prone to dependence.
The phases of dependence can be defined by different
clinical characteristics in relation to dose, administration
route, and length and pattern of cocaine use. There are
positive correlations between drug abuse liability, inten-
sity of intoxication and reported euphoria, with bioavail-
ability of the substance in the central nervous system, and
speed at which the maximum concentration in the brain
is reached after ingestion. Consequently, route of admin-
istration can have important implications in the develop-
ment of addictive behaviour(s). Crack cocaine, in
comparison to cocaine hydrochloride, or powder cocaine,
provides an immediate euphoric effect and is associated
with high dependence liability and distinct treatment out-
comes [4-6]. Intriguingly, studies investigating changes in
routes of administration and patterns of cocaine use in
Brazil demonstrated an important increase in the number
of people reporting crack cocaine use in the last decade [7-
12]. Although some of these studies identified three dis-
tinct groups of users [9,10,12]: 1) individuals who were
only snorting cocaine, 2) individuals who were only
smoking cocaine and 3) a large group of individuals who
were using both routes of administration concurrently,
characterization and comparisons have tended to con-
sider two groups only: crack and powder cocaine users,
where patients reporting more than one route were
counted per route [9,12].
The present study describes the socio-demographic char-
acteristics and drug abuse history among cocaine users
from Sao Paulo, aiming to better characterize the different
subgroups of users divided by their preferred form of use
and route of administration, focusing on the analysis of
dual users separately from the ones who use crack or pow-
der cocaine only.
Methods
Sampling
Although this sample is essentially a convenience sample,
it was intentionally selected from a wide range of services
with diverse characteristics to avoid an ascertainment bias
[13]. The study group consisted of drug users who were in
detoxification, abstinence or counselling treatment from
August 1997 to October 1998 in six inpatients and one
outpatient clinic located in the metropolitan region of São
Paulo City. The catchment area comprises the population
of Sao Paulo and 39 smaller surrounding cities, the largest
Brazilian (and South American) urban area. These drug
treatment centres accounted for an estimated 75% of all
hospitalizations related to drug abuse or illegal drug
dependence carried out during the study period.
Subjects
Inclusion criteria were: age 18 years and older, a history of
primary or only cocaine abuse and under treatment at the
selected centres. Individuals with history of exclusive alco-
hol dependence and mental disability were excluded. A
total of 699 patients were interviewed and gave written
informed consent. Subjects also gave a small sample of
blood for genetic studies and HIV testing. This project was
approved by the Ethical Committee of the Federal Univer-
sity of São Paulo and other relevant local ethics commit-
tees. HIV incidence investigation and a subgroup profile
description were published previously [12,15].
Measurements
A structure interview schedule in Portuguese had been
designed specifically for the Brazilian population [14] and
was comprehensively piloted previously. The question-
naire covers socio-demographic characteristics, sexual
behaviours, and drug use profile. Responses to questions
were dichotomous, multiple-choice or numeric in format.
As the majority of the questions had a screening approach,
the time taken to complete the interview was approxi-
mately 20 minutes (for details, see Ferreira-Filho et al,
2003). Interviews were conducted by three researchers,
either experienced psychiatrists or psychologists who had
been trained to use the questionnaire. All subjects satis-
fied an ICD10 diagnosis [16] of cocaine dependence (ICD
10 code F14.2).
Statistical analyses
A datafile was created for use with SPSS statistical soft-
ware, v.12.0. The statistical significance of differences
between the groups was established using either an
ANOVA test for comparisons of means or a χ
2
test for
comparison of categorical data. In addition the Kol-
mogorov-Smirnov Test was used for analyses of continuous,
non-parametric data.
Results
The study sample comprised 699 Cocaine Users. The pre-
dominant preferred forms of administration were powder
cocaine for 22.6% of the participants and crack cocaine
for 7.9% while the majority, 69.5%, reported using both
routes concurrently. In order to conduct a comparative
analysis the sample was divided as follows: 1) Powder
Cocaine Users, individuals who used cocaine or powder
cocaine 2) Crack Cocaine Users, individuals who used the
freebase processed cocaine hydrochloride commonly
known as "crack" and 3) Dual users, individuals who
reported using both forms of cocaine.
Socio demographic characteristics
A summary of socio demographic data is presented in
Table 1. Ninety-five per cent of the sample (n = 668) were
male, and this proportion was consistent among the three

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cocaine groups. The same consistency between groups was
found when marriage status was analyzed: 60.4% were
single, 26% were married or co-habiting and 13.6% were
divorced, separated or widowed at the time of the inter-
view. However, when age (F = 4.3; df
b
= 2; df
w
= 696; p =
0.01), ethnic background (χ
2
= 7.9; df = 2; p = 0.01) and
level of education (χ
2
= 14.1, df = 2, p = 0.001) were eval-
uated, statistic differences among groups could be identi-
fied.
Dual Users tended to be younger (26.2; SD = 6.8) and have
a higher percentage (30%) of individuals with self-
reported African ancestry than Powder Cocaine Users (28.1
years; SD = 7.7 and 20%, respectively); (F = 8.6, df
b
= 1;
df
w
= 642, p = 0.003 and χ
2
= 5.7, df = 1, p = 0.017, respec-
tively), but did not statistically differ from Crack Cocaine
Users (26.8 years; SD = 7.3 and 37%, respectively), (F =
0.4, df
b
= 1; df
w
= 539, p > 0.05 and χ
2
= 1.2, df = 1, p >
0.05, respectively). Education attainment differed in the
Dual Users, with 27% of the individuals having attended
the secondary school/university (ages 15 and over), versus
38% in Powder Cocaine Users (χ
2
= 7.1, df = 1, p = 0.007)
and was higher when compared with 13% in the Crack
Cocaine Users (χ
2
= 4.9, df = 1, p = 0.02).
Licit drug Use
Eighty-four percent (n = 588) of the patients were smokers
(Table 2). The percentage of smoking individuals was
88% in the Dual Users versus 74% in Powder Cocaine Users
(χ
2
= 16.6, df = 1, p < 0.0001) and 85% in Crack Cocaine
Users (χ
2
= 0.2, df = 1, p > 0.05). Regarding alcohol con-
sumption, Dual Users reported to drink more alcohol per
Table 1: Comparison of socio-demographic characteristics among Powder Cocaine Users, Crack Cocaine Users and Dual Users groups.
Powder Cocaine Users Crack Cocaine Users Dual Users Total pvalue
Age 28.1 26.8 26.2 26.7 p = 0.01
SD = 7.7 SD = 7.3 SD = 6.8 7.2
Ethnicity
Caucasian 125 80% 34 63% 339 70% 498 p = 0.01
African 31 20% 20 37% 143 30% 194
Sex
Male 149 94% 54 98% 465 96% 668 p > 0.05
Female 9 6% 1 2% 21 4% 31
Education
primary school or less 92 62% 47 87% 347 73% 486 P = 0.001
secondary school or more 57 38% 7 13% 127 27% 191
Marriage Status
single 96 61% 34 62% 289 60% 419 p > 0.05
married/cohabiting 37 23% 15 27% 128 27% 180
divorced/widowed 25 16% 6 11% 63 13% 94
Table 2: Comparison of history of legal and illegal drugs in the Powder Cocaine Users, Crack Cocaine Users and Dual Users groups and in
the total sample.
Powder Cocaine Users Crack Cocaine Users Dual Users Total pvalue
Alcohol
<50 units/
week
92 58% 40 73% 299 63% 431 p > 0.05
>50 units/
week
66 42% 15 27% 175 37% 256
Smoking
yes 117 74% 46 85% 425 88% 588 p > 0.001
no 41 26% 8 15% 60 12% 109
Cannabis
never used 11 7% 6 11% 8 2% 25 p > 0.0001
ever used 147 93% 49 89% 469 98% 665
Solvents
never used 70 44% 29 53% 118 24% 217 p > 0.0001
ever used 88 56% 26 47% 367 76% 481
Heroin
never used 153 97% 54 98% 459 94% 666 p > 0.05
ever used 5 3% 1 2% 27 6% 33

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week than Crack Cocaine Users (ks = 1.6, p = 0.01) Moreo-
ver 37% of the Dual Users reported consuming more than
50 units of alcohol per week, compared to 27% of the
Crack Cocaine Users (χ
2
= 1.9, df = 1, p > 0.05) and 42% of
the Powder Cocaine Users (χ
2
= 3.6, df = 1, p = 0.05).
Illicit drug use
When history of other illegal drugs was evaluated in the
three groups, differences were found for cannabis (χ
2
=
18.6, df = 2, p < 0.0001) and solvents (χ
2
= 35.2, df = 2, p
< 0.0001) but not for heroin use (χ
2
= 2.6, df = 2, p > 0.05,
see Table 2). The proportion of individuals that had ever
used cannabis was higher in the Dual Users group when
compared to both Powder Cocaine Users group (χ
2
= 11.4,
df = 1, p = 0.001) and Crack Cocaine Users (χ
2
= 16.4, df =
1, p < 0.001). Similar figures were observed for the use of
solvents, with a increased number of individuals in the
Dual Users group reporting to have ever used this sub-
stance in their life, compared to the Powder Cocaine Users
and Crack Cocaine Users groups (χ
2
= 22.9, df = 1, p <
0.0001 and χ
2
= 20.1, df = 1, p < 0.0001, respectively).
The use of both solvents and heroin in the last month
prior to admission was low overall and did not differ
among groups. The highest rates were 1.8% for the use of
solvents by the Crack Cocaine Users group and 0.8% for
use of heroin in the Dual Users group. While the reported
use of cannabis in the last month was high in all groups,
it was particularly raised in the Dual Users (63%) as com-
pared to Powder Cocaine Users (43%, χ
2
= 19.2, df = 1, p <
0.001) and Crack Cocaine Users (45%, χ
2
= 6.3, df = 1, p =
0.01).
Initiation into cocaine use
The most common first routes of cocaine administration
were snorting (n = 571), then smoking (n = 184) and
injecting (n = 50) – counting per route for individuals
who reported two or more concomitant first routes. Sepa-
rating the groups, snorting was the first route of choice for
93% of the Powder Cocaine Users and for 71% of the Dual
Users. However, in the Crack Cocaine Users group, the first
chosen route was smoking in 92% of the individuals (Fig-
ure 1), followed by snorting cocaine in only 8% of the
individuals. The mean age of initiation of cocaine use was
significantly different among the groups. Dual Users tend
to start using cocaine earlier (18.3 years, SD = 5.4) than
the Powder Cocaine Users (20.7 years, SD = 7.4) (F = 18.1,
df
b
= 1; df
w
= 641, p < 0.0001) and the Crack Cocaine Users.
The first route of administration in the Powder Cocaine Users, Crack Cocaine Users and Dual Users groupsFigure 1
The first route of administration in the Powder Cocaine Users, Crack Cocaine Users and Dual Users groups.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Powder Cocaine Users Crack Cocaine Users Dual Users
snorting
smoking
injec ting

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(22.7 years, SD = 8.1) (F = 28.4, df
b
= 1; df
w
= 539, p <
0.0001).
Criminal history
In relation to criminal history, 53% of the patients had
been in prison at some stage in their life. This rate was
higher in the Dual Users group (59%) in comparison to
the Powder Cocaine Users group (36.7%) (χ
2
= 23.7, df = 1,
p < 0.0001) and was non-significantly lower in the Crack
Cocaine Users (49%) (χ
2
= 2.6, df = 1, p = 0.1).
Discussion
In this study we describe socio-demographic characteris-
tics and history of licit and illicit drugs of abuse among
699 Cocaine Users recruited from seven drug treatment
hospitals located in the metropolitan region of Sao Paulo,
Brazil. The analyses were conducted dividing the sample
according to the preferred form of cocaine administration:
1) Powder Cocaine Users; 2) Crack Cocaine Users and 3)
Dual users. The high frequency of concomitant use of crack
with powder cocaine in our sample may be partly due to
an increased availability – and a concomitant reduction in
the price – of crack cocaine that occurred in the early
1990's, which led to an explosion in consumption. Dunn
et al. (1996) [7] and Ferri and Gossop (1999, 2001) [9,10]
also reported increased crack use among patients who
sought treatment in Sao Paulo clinics over this period.
This had important social implications since crack cocaine
users are more likely to report craving and impaired con-
trol of their drug use, tend to present higher levels of sever-
ity of dependence, higher involvement in prostitution,
violence and crime [17,18].
With respect to socio-demographic characteristics, our
sample was essentially comprised of young, single, men
with mainly primary education, corroborating previous
published data about cocaine users attending treatment in
Sao Paulo [8,9,11]. Comparing the different groups, Dual
Users tended to differ from Powder Cocaine Users, regarding
age, self-reported ethnicity, educational attainment and
smoking status. Moreover, a high proportion of alcohol
consumption was found in our sample with Dual Users
reporting to drink more alcohol per week than Crack
Cocaine Users. High prevalence for concurrent alcohol and
cocaine misuse has been reported [9,10]. Epidemiological
studies indicate that simultaneous abuse of powder
cocaine and alcohol is widespread [19] and it is known
that concurrent ingestion of cocaine and alcohol results in
cocaethylene production [20,21]. Cocaethylene is a phar-
macologically active homolog of cocaine with an
increased metabolic half-life and may play a role in rein-
forcement effects of cocaine.
In addition, regarding the history of use of illicit drugs,
Dual Users demonstrated a higher proportion of individu-
als that had ever used cannabis and solvents in their life
and cannabis in the last month. Polydrug abuse is a phe-
nomenon reported by cocaine users in several other stud-
ies [7,10,22] and represents an important concern to
treatment and public health strategies. Polydrug users
show complex life histories and are normally associated
with poorer treatment outcomes than those using one
drug only [22]. The latest data on hospital emergency vis-
its estimates that more than half of the visits related to
"drug misuse or abuse" involved more than one drug [23]
and recent studies reported that simultaneous use of mul-
tiple drugs has been shown to contribute substantially to
overdose mortality [24,25]. However, contrasting with the
previously mentioned studies and with surveys in Europe
where the consumption of opiates by cocaine users was
important [26], the recent consumption of heroin was
particularly low in our sample, reported by only 4
patients, less than 1% of the sample."
Eight-one per cent of our sample began using cocaine by
snorting, agreeing with a previous study where 84% of the
cocaine users in Sao Paulo [8] had chosen this route on
the first occasion. Although the majority of the sample
reported first use of cocaine by this route, 68% of those
individuals went on to experience crack cocaine and 9%
injected cocaine at some time of their life. However, when
current Crack Cocaine Users were analyzed separately,
ninety-two per cent of those reported first use of cocaine
by smoking and, here, a smaller proportion of individuals
went on experience powder cocaine (43%) or injected
cocaine (4%). Interestingly most Dual Users (66%) started
using powder cocaine and then moved onto crack, sup-
porting the suggestion that hydrochloride used intrana-
sally may be a gateway drug or behaviour to using crack
cocaine [17].
The presence of substance abuse and dependence are par-
ticularly associated with an increased risk of violent/hom-
icidal behaviours [27]. Criminal activity was notably
present in our sample. The Dual users groups were more
likely to have been imprisoned in their life than the Pow-
der Cocaine Users. Hatsukami and Fischman (1996) [17]
reported crack cocaine to be linked with crime to a greater
extent than cocaine hydrochloride, with many of these
crimes being associated with the maintenance of drug
consumption.
In summary, we found a high consumption of crack
cocaine among the patients, corroborating with a historic
change in the preference of cocaine use in Brazil in the
past decade, reported by earlier studies. Furthermore we
showed for the first time that interesting differences exist
between Powdered, Crack and Dual Cocaine Users, a sepa-
rate group, usually not considered in previous studies. The
findings suggest that the Dual Users group differs from the

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mono users in several of the variables tested and appeared
to be a distinct and more severe group regarding history of
illicit drug abuse and rates of criminal history. They
tended to have consumed significantly more cannabis and
solvents. Moreover they also started consuming cocaine
earlier in life and they were more likely to be actively
involved in crime, showing higher percentage of individ-
uals who have been arrested at least once in their life.
Conclusion
In conclusion, our results tended to agree with previous
studies about cocaine and crack use in Brazil while offer-
ing some new information regarding the individuals who
report use of both powder and crack cocaine. In the
present study, this group presents differences to mono
users, which suggests these individuals may be considered
as a separate group. The main limitations of this study
were that a small amount of information was available for
certain key variables, e.g., for criminal history we did not
record whether or not the conviction was for anti-social or
violent behaviour, and that we had to rely on patient self
report for other measures such as concomitant drug and
alcohol use. However, the sample was large and from
seven different centres, thus we might expect that the
observations are clinically relevant, at least for the urban
region of Sao Paulo.
Competing interests
The author(s) declare that they have no competing inter-
ests.
Authors' contributions
CG and GB analyzed the data, carried out statistical anal-
ysis and wrote the paper. RL was the psychiatrist coordina-
tor of the sample collection. RL and HV participated in
study design, and helped to revise drafts of the manu-
script. All authors read and approved the final manu-
script.
Acknowledgements
GB is an MRC Bioinformatics Training Fellow. This work was in part sup-
ported by FAPESP (Fundação para o Amparo à Pesquisa do Estado de São
Paulo) and CAPEs (Coordenação de Aperfeiçoamento de Pessoal de Nível
Superior).
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