Sex worker health: San Francisco style
D Cohan, A Lutnick, P Davidson, C Cloniger, A Herlyn, J Breyer, C Cobaugh, D Wilson,
............................................................... ............................................................... .
See end of article for
Deborah Cohan, MD,
MPH, UCSF, 1001 Potrero
Avenue, Ward 6D San
Francisco General Hospital
Department of Obstetrics/
Francisco, CA 94110
Accepted for publication
20 June 2006
Published Online First
19 July 2006
Sex Transm Infect 2006;82:418–422. doi: 10.1136/sti.2006.020628
Objectives: To describe the characteristics of sex workers accessing care at a peer based clinic in San
Francisco and to evaluate predictors of sexually transmitted infections (STI).
Methods: We conducted an observational study of sex workers at St James Infirmary. Individuals
underwent an initial questionnaire, and we offered screening for STI at each clinic visit. We performed
univariate, bivariate, and multivariable analyses to assess for predictors of STI in this population.
Results: We saw 783 sex workers identifying as female (53.6%), male (23.9%), male to female
transgender (16.1%), and other (6.5%). 70% had never disclosed their sex work to a medical provider.
Participants represented a wide range of ethnicities, educational backgrounds, and types of sex work. The
most common substance used was tobacco (45.8%). Nearly 40% reported current illicit drug use. Over half
reported domestic violence, and 36.0% reported sex work related violence. Those screened had
gonorrhoea (12.4%), chlamydia (6.8%), syphilis (1.8%), or herpes simplex virus 2 (34.3%). Predictors of
STI included African-American race (odds ratio (OR) 3.3), male gender (OR 1.9), and sex work related
violence (OR 1.9). In contrast, participants who had only ever engaged in collective sex work were less
likely to have an STI (OR 0.4).
Conclusions: The majority of sex workers have never discussed their work with a medical provider.
Domestic violence is extremely prevalent as is work related violence. Working with other sex workers
appears to be protective of STIs. STI prevention interventions should target African-American and male sex
workers. Addressing violence in the workplace and encouraging sex workers to work collectively may be
effective prevention strategies.
Leaders from the sex worker community, in collaboration
with the San Francisco Department of Public Health STD
Prevention and Control Section, started the clinic.1–3The
stated mission of SJI is to provide compassionate and non-
judgmental health care and social services for all sex workers
while preventing occupational illnesses and injuries through
a comprehensive continuum of services.4SJI is a weekly, peer
based clinic, with the majority of staff and board members
being former or current sex workers. The clinic uses a harm
reduction approach, with an emphasis on engaging sex
workers in addition to identifying and reducing the indivi-
dual and community level risks associated with sex work.5
Services offered include primary medical care, HIV and STI
screening and treatment, transgender health, harm reduction
and peer counselling, psychiatric evaluation and manage-
ment, acupuncture, massage, support groups, food, clothing,
and needle exchange. Additionally, clinic staff distributes
safer sex supplies and offers HIV testing to sex workers in the
setting of street and venue based outreach.6The purpose of
this study is to describe the characteristics of sex workers
accessing health care at this specialty sex worker clinic and to
evaluate predictors of sexually transmitted infections (STI)
among those sex workers testing for gonorrhoea, chlamydia,
syphilis and herpes simplex virus 2 (HSV-2).
n June of 1999, the St James Infirmary (SJI) began
providing free medical services for male, female and
transgender sex workers in the San Francisco Bay Area.
Since September 1999, we have been conducting an ongoing,
prospective evaluation of all individuals accessing care at SJI.
We limited this analysis to those current or past sex workers
who sought care at SJI between September 1999 and
November 2004. We defined sex work as the provision of
sexual services or performances in exchange for money or
goods of economic value including but not limited to drugs,
housing, and food.7Peer counsellors administered a struc-
tured intake questionnaire to sex workers during their initial
visit to SJI. The questionnaire ascertained demographics, sex
work history, drug use, social support, legal history, and
violence. We modified the questionnaire in September 2001
to include additional questions about previous HIV and STI
diagnoses, past drug use, and mental health history.
At the initial and any subsequent clinic visits, SJI staff
offered voluntary screening for STI to all clinic patients. The
medical providers and/or harm reduction counsellors decided
which test(s) to obtain based on patient request and clinical
judgment. In particular, all individuals reporting unprotected
oral, vaginal, and/or anal intercourse were encouraged to
undergo STI screening. There were no set screening intervals.
Screening included pharyngeal, rectal, and urine based
chlamydia (CT) and gonorrhoea (GC) nucleic acid amplifica-
tion tests (LCx, Abbott Labs and BDProbeTec, Becton
Dickinson) as well as syphilis (Venereal Disease Research
Laboratory Slide Test (VDRL) with confirmatory SerodiaTP-
PA, Fujirebio, Inc) and HSV-2 antibodies (HerpeSelect 2
ELISA for HSV IgG, Focus Diagnostics).
Predictor variables included demographics, history of pre-
vious HIV and STI diagnosis, and behaviour self reported in
the questionnaire. We analysed each type of sex work as a
Abbreviations: BDSM, bondage-dominatrix-sado-masochism; CT,
chlamydia; GC, gonorrhoea; HSV, herpes simplex virus; IDU, injecting
drug use; MTF, male to female; SJI, St James Infirmary; STI, sexually
distinct predictor variable. For the purpose of multivariable
analysis, we categorised the sex workers into three mutually
exclusive groups—those who had engaged in exclusively
independent sex work, both independent and collective sex
work, and exclusively collective sex work. Independent sex
work included street based, independent massage, indepen-
dent in-call/out-call, sex trades, webcam based sex work,
phone sex, and independent modelling. Collective sex work
included massage parlours, escort, brothels, stripping, bon-
dage-dominatrix-sado-masochism (BDSM), and pornogra-
phy. The main outcome variable was any positive chlamydia,
gonorrhoea, syphilis, or HSV-2 screening test. Some indivi-
duals underwent repeat STI screening, so we calculated the
percentage of positive STI results as the proportion of
unduplicated sex workers with any positive test among the
total population of individuals testing. We performed
univariate analysis, calculating proportions and means/
medians for the demographic, health history and behavioural
data, as appropriate. We then performed bivariate analysis,
using the x2test or Fisher’s exact test for categorical variables
and Student’s t test for continuous predictor variables. We
assessed for multicollinearity and normal distribution. We
performed logistic regression using forward stepwise techni-
que including those variables with a p value ,0.2 by bivariate
analysis.8A p value of ,0.05 was considered statistically
significant. We evaluated all models using likelihood ratio
and goodness of fit tests and conducted all analyses using
Stata SE 8.0 statistical software (College Station, TX, USA).
We obtained approval to conduct this study by the
California San Francisco.
at theUniversity of
Overall, we conducted intake questionnaires on 783 sex
workers who identified as female (53.6%), male (23.9%),
male to female (MTF) transgender (16.1%), or other gender
(6.5%). Of these 783 sex workers, 230 underwent the original
intake questionnaire and the remaining 553 were adminis-
tered the modified intake questionnaire. Table 1 shows the
characteristics of participants.
The mean age of participants was 33.1 (SD) 9.4; range 17–
76), and this differed significantly by gender. Race/ethnicity
and educational level also differed significantly by gender.
As described in figure 1, clinic attendees participated in a
diverse array of sex work activities including street based,
massage parlour, independent sexual massage, escort, inde-
trades (for example, for housing, drugs, food), BDSM,
webcam/internet, phone sex, pornography and independent
modelling for customers. With sex specifically defined as oral,
anal, vaginal intercourse, sharing sex toys, and/or manual
stimulation, 95% of participants reported having sex as part
of their sex work, and this finding did not differ by gender,
though it vary by type of sex work. Strippers were less likely
to have sex as part of their sex work (86.3%; p,0.001) as
were those engaged in BDSM (85.7%; p,0.001).
Median age (range) (n=783)
Highest level of education (n=743)
High or technical school
College or grad school
Contact with family (n=783)
Presence of support network (n=783)
History of arrest (n=757)
Prostitution related conviction (n=757)
Partner/family violence (n=783)
Sex work related violence (n=783)
Disclosure to medical provider (n=714)
33.1 (17–76) 33 (17–58) 30 (17–76) 35 (18–60) 31 (18–76)
MTF, male to female.
Types of sex work.
Sex worker health419
Overall, 69.4% of participants stated that they were in contact
with their family, though MTF were less likely to be so.
Eighty one per cent of sex workers reported having a support
network or community. The presence of a network/commu-
nity did not differ by gender but did by current type of sex
work. Street based sex workers were less likely to have a
network/community (60.0%; p,0.001). On the other hand,
strippers were more likely to report having a network/
community (93.1%; p=0.001) as were those involved with
BDSM (91.1%; p,0.05).
Almost half of participants had been arrested in the past,
with MTF sex workers more likely to be arrested and
convicted of sex work related charges. Those most likely to
be arrested included those involved with street based work
(74.2%; p,0.001), sex trades (63.7%; p,0.001), and escort
Fifty three per cent of participants reported a history of
family/partner violence. In addition, 36.0% reported a history
of sex work related violence. MTF sex workers were at
significantly higher risk of work violence, customer violence,
and police violence. Also at higher risk of work related
violence included those engaged in street based sex work
(61.8%; p,0.001), sex trades (56.6%; p,0.001), massage
parlours (48.1%; p=0.01), and stripping (43.2%; p,0.05).
Legal history was also significantly associated with violence,
with 47.1% of those ever arrested experiencing work related
violence compared to 25.9% of those without a history of
Sex work disclosure
Seventy per cent of patients had never disclosed their sex
work to a healthcare provider before their initial visit to SJI.
MTF sex workers were significantly more likely to disclose to
providers. The reasons for not disclosing one’s sex work
history included negative past experiences with disclosure
(4.8%), fear of disapproval (31.2%), embarrassment (7.6%),
and not thinking their sex work was relevant to their health
The most common substance reported was tobacco, with
46.0% of participants currently smoking (table 2).
Nearly 40% of participants reported current illicit drug use.
Male sex workers were the most likely to be actively using
drugs, particularly methamphetamines. Although there were
no gender differences in current injecting drug use (IDU),
MTF were more likely to have a history of IDU and were more
likely to be current smokers.
Self reported history of STI
Forty four percent of sex workers described a history of any
STI, including genital herpes, gonorrhoea, chlamydia, genital
warts, syphilis, non-gonococcal urethritis, trichomonas, and
pelvic inflammatory disease. In addition, 91.2% of patients
had undergone HIV testing in the past, with 8.7% having
tested positive. Prevalence of known HIV infection was
highest among MTF and men.
Overall, 58.2% of patients underwent testing for STI.
Compared with those who did not test, STI testers were
significantly younger (31.8 v 34.8 years old), though testing
uptake did not differ by gender, current drug use, type of sex
work, or ethnicity. Those with a known diagnosis of HIV,
however, were significantly less likely to undergo STI
screening (39.5%; p,0.01). Among testers, the proportion
of those with at least one positive test included 34.3% for
HSV-2, 12.4% for gonorrhoea, 6.8% for chlamydia, and 1.8%
for syphilis. In bivariate analysis, there was no association
Health behaviour, STI history, and current STI
Variable % (n)MaleFemale MTFOtherp Value`
Illicit drug use ever (n=756)
History of IDU (n=756)
Any illicit drug (n=755)
Current injection drug use (n=756)
Self reported infections* (n=543)
Any STI? (n=456)
MTF, male to female; IDU, injecting drug use.
*These data were ascertained on the modified questionnaire only.
?Prevalence of any STI, gonorrhoea, chlamydia, HSV-2, and syphilis was calculated as the proportion of individuals with any positive STI result among all
individuals tested for each particular STI. Overall, 456 individual sex workers (58.2%) were tested for one or more STI.
`We performed a Fisher exact test if fewer than five outcomes in any category, otherwise we used a x2test.
420Cohan, Lutnick, Davidson, et al
found between presence of an STI and educational level, drug
use, domestic violence or violence in the setting of sex work.
African-American sex workers were at highest risk of
having an STI (50%; p,0.001) and, specifically, HSV-2
(70.6%; p=0.001). Those ever engaging in escort work were
more likely to be diagnosed with any STI (35.7%; p,0.05), as
were those engaging in phone sex (43.6%; p=0.001).
Another predictor of positive STI included a history of
chlamydia (40.4%; p,0.05). Eighty per cent of those with a
reported history of genital herpes were found to have
antibodies against HSV-2, and over 34% of those without a
known history of genital herpes were found to have HSV-2
antibodies (p,0.05). Lastly, those with a history of arrest
were more likely to have an STI (27.4%; p,0.05).
In multivariable analysis, predictors of testing positive for
an STI included African-American race (OR 3.3; 95%
confidence interval (CI) 1.3 to 8.3), male gender (OR 1.9,
95% CI 1.0 to 3.6), and having a history of sex work related
violence (OR 1.9; 95% CI 1.1 to 3.3). On the other hand, those
with a history of only engaging in collective sex work were
significantly less likely to test positive for an STI (OR 0.4; 95%
CI 0.1 to 0.9).
By characterising sex workers seeking care at a peer based
specialty clinic, we have gained a window into the diverse sex
industry in San Francisco. The sex workers covered a wide
range of socioeconomic and racial/ethnic backgrounds and
engaged in an extensive array of types of sex work.9Even
defining sex work broadly, nearly all of these individuals,
including strippers and phone sex workers, reported being
sexually active in their sex work.
As has been seen in other studies, sex workers commonly
reported illicit drug use.10As we have demonstrated before,
however, the most common substance used in this popula-
tion was tobacco.11Violence, particularly at the hands of
partners and family members, was markedly common in the
lives of the sex workers we studied.12We also demonstrated
the significant risk of customer, sex work employer/manager/
pimp, and police related violence.12 13Street based and sex
trade sex workers had the highest risk of sex work violence.
None the less, many types of ‘‘indoor’’ sex work, including
massage and stripping, were also associated with an
increased risk of work related violence.14
While nearly all participants had previously tested for HIV,
the vast majority had never discussed their sex work history
in the healthcare setting. In our study, both self reported
history of STI and documented STI prevalence was, overall,
lower than has been seen in other studies of urban sex
workers.11 15–17None the less, there were factors found to be
associated with increased risk of STI in this population,
including African-American race, male gender, and sex work
related violence. Furthermore, risk of STI differed significantly
by type of sex work. Interestingly, those working collectively
with other sex workers were less likely to have an STI.
While this study depicts the landscape of the sex industry
in San Francisco, there certainly are limitations. In particular,
we had limited information on specific sexual practices with
different types of sexual partners and, thus, could not fully
explore the complex set of factors that constitute STI risk.
While we attempted to ascertain detailed sexual histories,
many of the sex workers expressed difficulty in accurately
quantifying the number of partners and sex acts. Another
limitation of this study was the use of a convenience sample
of sex workers accessing health care at a sex work specific
clinic. This self selected population may not represent the
larger population of female, male, and transgender sex
workers in San Francisco and, therefore, estimates of STI
Predictors of STI among sex workers: bivariate and multivariable analyses
STI testingSTI positive Odds ratio (95% CI)
% (n) % (n)UnadjustedAdjusted*
All participants (n=783)
Predictor variable (n)
Asian-Pacific Islander (67)
Native American (14)
Middle school or less (52)
High or technical school (336)
College or grad school (355)
Type of sex work (ever)
Independent only (218)
Collective and independent (336)
Collective only (143)
Sex work related violence (282)
Domestic violence (418)
History of arrest (374)
Sex work related conviction (62)
Tobacco use (current) (348)
Illegal drug use (current) (299)
Injection drug use (current) (60)
58.2 (456)23.0 (105)
3.8 (1.8 to 7.8)
0.7 (0.4 to 1.0)
1.4 (0.7 to 2.7)
0.7 (0.3 to 1.5)
0.6 (0.1 to 4.6)
1.0 (0.5 to 1.9)
3.3 (1.3 to 8.3)
1.9 (1.2 to 3.0)
0.5 (0.3 to 0.8)
1.1 (0.6 to 2.0)
1.5 (0.5 to 3.9)
1.9 (1.0 to 3.6)
0.5 (0.2 to 1.5)
0.9 (0.6 to 1.4)
1.3 (0.8 to 1.9)
1.5 (0.9 to 2.4)
1.2 (0.8 to 1.8)
0.4 (0.2 to 0.8)0.4 (0.1 to 0.9)
1.9 (1.1 to 3.3)
56.7 (237)24.9 (59)1.2 (0.8 to 1.9)
1.6 (1.0 to 2.4)
1.4 (0.6 to 3.0)
1.6 (1.0 to 2.4)
0.8 (0.5 to 1.3)
1.0 (0.4 to 2.3)
*Final multivariable model built using forward stepwise technique, including variables significant at p,0.2 in bivariate analysis. The final multivariable model
adjusted for age, race/ethnicity, educational level, category of sex work, current drug use, and history of sex work related violence.
Sex worker health 421
prevalence may be biased. Furthermore, STI screening was Download full-text
offered to but not performed on all patients. Furthermore,
repeat testing and the interval of such testing were,
ultimately, decided by each individual patient.
Despite these limitations, there is value in assessing the local
sex work environment and using this as the basis for public
to maximise the uptake of voluntary STI screening, particularly
among HIV infected sex workers. This study suggests that STI
prevention efforts in San Francisco must increasingly target sex
workers who are African-American, male, and work indepen-
dently of other sex workers. Moreover, anti-violence interven-
tions should be an integral part of STI prevention. Our finding
of decreased risk of STI among those individuals who have
worked collectively with other sex workers is intriguing and
warrants further study.
The St James Infirmary represents a novel collaborative
effort between public health officials and the sex worker
community. Through this unique model, sex workers have
helped define public health priorities for their own commu-
nity and public health officials have gained access to this
hidden and stigmatised population.
We thank all the sex workers who participated in this study, the staff
and volunteers at St James Infirmary, and the staff at City Clinic/
Department of Public Health, including Wendy Wolf, Bob Kohn,
Charlotte Kent, and Dr Will Wong.
D Cohan, A Lutnick, UCSF, 1001 Potrero Avenue, Ward 6D San
Francisco General Hospital Department of Obstetrics/Gynecology San
Francisco, CA 94110 USA
P Davidson, University of California, San Francisco Department of
Social and Behavioral Sciences, California, USA
C Cloniger, San Francisco Department of Public Health, California, USA
A Herlyn, University of California, San Francisco, California, USA
J Breyer, C Cobaugh, D Wilson, St James Infirmary and University of
California, San Francisco, California, USA
J Klausner, San Francisco Department of Public Health and University of
California, San Francisco Department of Medicine, California, USA
Funding: This study was supported by the National Institute for Drug
Abuse (K23 DA01674), the Ford Foundation, the San Francisco
Department of Public Health, and the University of California San
Francisco School of Medicine Student Research Training Program.
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422Cohan, Lutnick, Davidson, et al