Estimating the lesbian population: a capture-recapture approach

Estimating hidden populations by transferring knowledge from geographically misaligned levels

The estimation of hidden sub-populations is a hard task that appears in many fields. For example, public health planning in Brazil depends crucially of the number of people who holds a private health insurance plan and hence rarely uses the public services. Different sources of information about these sub-populations may be available at different geographical levels. The available information can be transferred between these different geographic levels to improve the estimation of the hidden population size. In this study, we propose a model that use individual level information to learn about the dependence between the response variable and explanatory variables by proposing a family of link functions with asymptotes that are flexible enough to represent the real aspects of the data and robust to departures from the model. We use the fitted model to estimate the size of the sub-population at any desired level. We illustrate our methodology estimating the sub-population that uses the public health system in each neighborhood of large cities in Brazil.

[Barriers to sexual health care in Argentina: perception of women who have sex with women]

Objective The objective is to describe the barriers to sexual health care of Women Who Have Sex with Women (WSW) in Argentina during 2013. Methods A cross-sectional, descriptive and quantitative study. An online survey was conducted using the Internet, in the period of April-July 2013, with homosexual and bisexual women over 18 living in Argentina, making use of the snowball methodology. Results A total of 161 women were surveyed. The results showed that 97.5 % had previously visited a doctor. The doctor did not ask about their sexual orientation in 82.8 % of cases. 93.6 % of the surveyed did not receive information about STDs; 83.8 % perceive little/no risk regarding STDs. 48.4 % are unaware of the methods of protection of STDs among women and 51.6 % obtained this information from websites and friends. 77.5 % reported not using protection methods. The main reasons were: stable partner, discomfort and the inability to acquire them. Discussion The results of this research allow for identifying the low perception among WSW regarding STDs, and the difficulty of approaching health professionals about this subject.

Hazardous waste site frequency: use of the capture-recapture method

This investigation used a two-source capture-recapture method (CRM) for determining ascertainment and undercounts of non-national priority listed hazardous waste sites in the states of Arizona, Maine and Pennsylvania. These findings suggest that ascertainment of hazardous waste sites vary greatly, with some more accurate (i.e., Maine) than others (i.e., Pennsylvania). These data suggest that nontraditional manufacturing states (e.g., Maine) have a higher ascertainment rate than traditional manufacturing states (e.g., Pennsylvania). These results indicate that resources for locating hazardous waste sites should be more heavily allotted to industrialized areas. We suggest that the CRM is a convenient, low cost and effective method for determining (1) the accuracy of previous estimates, and (2) the number of sites in a locale with 95% confidence intervals along with an estimate of the undercount. Findings suggest that estimates of hazardous waste sites should use the CRM to determine and improve accuracy.

Chlamydia trachomatis infection in African American women who exclusively have sex with women

Little is known about whether Chlamydia trachomatis can be sexually transmitted between women or how often it occurs in women who have sex with women (WSW). We investigated Chlamydia trachomatis prevalence and serum Chlamydia trachomatis-specific antibody responses among African American WSW who reported a lifetime history of sex only with women (exclusive WSW) (n = 21) vs. an age-matched group of women reporting sex with women and men (WSWM) (n = 42). Participants completed a survey, underwent a pelvic examination in which a cervical swab was collected for Chlamydia trachomatis nucleic acid amplification testing (NAAT), and had serum tested for anti-Chlamydia trachomatis IgG1 and IgG3 antibodies using a Chlamydia trachomatis elementary body-based ELISA. No exclusive WSW had a positive Chlamydia trachomatis NAAT vs. 5 (11.9%) WSWM having a positive Chlamydia trachomatis NAAT (p = 0.16). Compared with WSWM, WSW were significantly less likely to be Chlamydia trachomatis seropositive (7 [33.3%] vs. 29 [69%], p = 0.007). Among Chlamydia trachomatis seropositive women, all were seropositive by IgG1, and the magnitude of Chlamydia trachomatis-specific IgG1 responses did not differ in Chlamydia trachomatis-seropositive WSW vs. WSWM. In conclusion, Chlamydia trachomatis seropositivity was relatively common in exclusive African American WSW, though significantly less common than in African American WSWM.

Prevalence of overactive bladder and stress urinary incontinence in women who have sex with women: an internet-based survey

Women who have sex with women (WSW) are a medically underserved population. Data on urologic health in WSW are scant. We hypothesized that the prevalence of urinary symptoms in WSW is similar to population norms and that urinary symptoms in WSW would be associated with known risk factors for urologic problems. WSW were recruited to participate in an internet-based survey via invitations, listserves, and social media. Primary outcome measures were the validated Overactive Bladder Questionnaire (OAB-q) and a single question assessing stress urinary incontinence (SUI). OAB status was dichotomized by OAB-q score (0-8=none/mild; >8=moderate/severe). SUI was dichotomized by single item response (none/little bit of the time=none/mild; sometimes through always=moderate/severe). Ethnodemographic, health, sexuality, and relationship data was also collected. Multivariable logistic regression utilizing 17 factors was performed with SAS V9.2, followed by multivariable analysis with stepwise selection based on the initial analysis (included factors, p<0.25). The final study population consisted of 1,566 adult WSW with mean age 34.6±10.4 years. Moderate/severe OAB was present in 354 (23%) women; 275 (18%) reported moderate /severe SUI. Concomitant OAB and SUI were present in 183 (12%). In multivariable analysis with stepwise selection, OAB symptoms were significantly associated with diabetes, history of urinary tract infection, gynecologic surgery, routine health care, and consultation with a provider regarding urinary symptoms. SUI symptoms were associated with sexual bother. This is the first survey report of prevalence and associations of OAB and SUI in a population of WSW. SUI and OAB were prevalent in WSW. Further attention to urological health in WSW is warranted.

[The lesbian population in health studies: contributions for a critical reflection]

For decades, lesbian sexuality was associated with pathology in the attitudes to and practices of health sciences and psychology. During the twentieth century that position changed gradually. This article analyzes these changes in a theoretical reflection on the domain of lesbian health, dominated by heteronormative and heterosexist concepts and practices both in research and in health care. By means of a critical contextualization of the literature, specific health needs of lesbians were identified and the interventions of health care professionals and services were questioned. Specific concrete actions are proposed in the fields of health promotion and in the eradication of discrimination and inequality in health care.

Epidemiology of primary Sjögren's syndrome in a French multiracial/multiethnic area

OBJECTIVE

To describe the epidemiology of primary Sjögren's syndrome (SS) in a multiracial/multiethnic population.

METHODS

A cross-sectional study with 5 case-retrieval sources identified adults with primary SS living in the Greater Paris area (population 1,172,482 adults) in 2007. Diagnoses were verified by the American-European Consensus Group (AECG) criteria and study-specific enlarged criteria based on the presence of ≥3 of 4 AECG items among subjective oral or ocular dryness, anti-SSA/SSB positivity, and positive minor salivary gland biopsy results. Prevalence estimates were standardized to those for the world population and a 5-source capture-recapture analysis (CRA) was used. Racial/ethnic differences in primary SS features were evaluated.

RESULTS

In all, 133 subjects met the AECG criteria and 203 met the enlarged criteria. The 2007 prevalence of primary SS was 1.02 cases per 10,000 adults (95% confidence interval [95% CI] 0.85-1.22) for the AECG criteria and 1.52 cases per 10,000 adults (95% CI 1.30-1.76) for the enlarged criteria. The CRA indicated completeness of case findings of ∼90%. Compared to subjects with European backgrounds, those with non-European backgrounds had 2.1-2.3 times higher primary SS prevalence and were younger (P < 0.0001) and were more likely to have polyclonal hypergammaglobulinemia (P < 0.0001) and anti-SSA/SSB antibodies (P = 0.0005 and P < 0.0001 for the AECG and enlarged criteria, respectively).

CONCLUSION

The figure of 1.02–1.52 cases per 10,000 adults we found and estimates from the few other population-based census surveys support that the prevalence of diagnosed primary SS is between 1 and 9 cases per 10,000 (0.01-0.09%) [corrected] in the general population. Non-European race/ethnicity may be associated with increased primary SS risk and a distinct disease profile.

Estimating rheumatic fever incidence in New Zealand using multiple data sources

Rheumatic fever (RF) is an important public health problem in New Zealand (NZ). There are three sources of RF surveillance data, all with major limitations that prevent NZ generating accurate epidemiological information. We aimed to estimate the likely RF incidence using multiple surveillance data sources. National RF hospitalization and notification data were obtained, covering the periods 1988-2011 and 1997-2011, respectively. Data were also obtained from four regional registers: Wellington, Waikato, Hawke's Bay and Rotorua. Coded patient identifiers were used to calculate the proportion of individuals who could be matched between datasets. Capture-recapture analyses were used to calculate the likely number of true RF cases for the period 1997-2011. A range of scenarios were used to correct for likely dataset incompleteness. The estimated sensitivity of each data source was calculated. Patients who were male, Māori or Pacific, aged 5-15 years and met the Jones criteria, were most likely to be matched between national datasets. All registers appeared incomplete. An average of 113 new initial cases occurred annually. Sensitivity was estimated at 80% for the hospitalization dataset and 60% for the notification dataset. There is a clear need to develop a high-quality RF surveillance system, such as a national register. Such a system could link important data sources to provide effective, comprehensive national surveillance to support both strategy-focused and control-focused activities, helping reduce the incidence and impact of this disease. It is important to remind clinicians that RF cases do occur outside the well-characterized high-risk group.

Use of barrier protection for sexual activity among women who have sex with women

OBJECTIVE

To assess the frequency and associations of barrier protection use during sexual activity in a population of women who have sex with women (WSW).

METHODS

WSW were invited to participate in an international internet-based survey. Information regarding ethnodemographics, sexual health, and barrier use during sexual activities was collected.

RESULTS

The study cohort comprised 1557 participants. Barrier use was least prevalent during digital genital stimulation (11.3% ever used barriers) and most prevalent during stimulation with a sex toy (34.4% ever used barriers). Univariate analysis revealed that women in non-monogamous relationships were more likely than monogamous women to always use barrier protection for sexual activity (14.3% vs 3.5%). On multivariate analysis, there was no association between barrier use and frequency of casual sexual activity or history of sexually transmitted infection. Small associations were noted between barrier use and certain sexual activities, age, race, and number of partners.

CONCLUSION

Many WSW do not use barrier protection during sexual activity, even in the context of potentially risky sexual behaviors. Safer-sex practices among WSW merit increased attention from healthcare providers and public health researchers.

An Internet survey of demographic and health factors associated with risk of sexual dysfunction in women who have sex with women

INTRODUCTION

There has been scant attention to predictors of sexual dysfunction in women who have sex with women (WSW).

AIM

To investigate the associations of high risk for sexual dysfunction in an Internet cohort of WSW.

MAIN OUTCOME MEASURE

A modified version of the Female Sexual Function Index (FSFI) was used to quantify each subject's sexual function.

METHODS

Women who have sex with women were invited to participate in an Internet-based survey by invitations posted on e-mail listservs and on social media sites catering to WSW. Ethnodemographic, health status, and sexual/relationship data were collected.

RESULTS

The study was completed by 2,433 adult women. Of these, 1,566 participants had complete data on the FSFI and comprised the study cohort; 388 (24.8%) met the FSFI criteria for high risk of female sexual dysfunction (HRFSD). On multivariable analysis, the following variables were found to be independently associated with the HRFSD; moderate or severe subjective bother regarding sexual function (OR 4.8, 95% CI 3.0-7.9 and 13.7, 95% CI 7.5-25.1, respectively), overactive bladder (OAB) (OR 2.1, 95% CI 1.0-4.5), having a nonfemale or no partner (OR 2.3, 95% CI 1.1-4.7 and 3.2, 95% CI 2.0-5.2, respectively). A history of pregnancy was associated with lower odds of HRFSD (OR 0.567, 95% CI 0.37-0.87). Mean FSFI domain scores for all domains except desire were negatively impacted by partner factors and OAB.

CONCLUSIONS

A single-item question on sexual bother is strongly predictive of potentially distressing sexual problems in the WSW. A number of health and social factors are associated with risk of sexual problems in the WSW. Assessment of sexual well-being in the WSW is a priority for practicing healthcare providers.

Under-registration of deaths in Thailand in 2005-2006: results of cross-matching data from two sources

OBJECTIVE

To estimate the magnitude of under-registration of deaths, by age and sex, in Thailand.

METHODS

THE DATA IN THIS STUDY WERE DERIVED FROM TWO SOURCES: the Thai Survey of Population Changes (SPC) 2005-2006, a consecutive multi-round household survey conducted over a 12-month period, and Thailand's vital registration records. SPC death entries for people of all ages were matched to 2005-2006 death records from vital registration. The principles of a dual records system were applied to estimate the magnitude of under-registration of deaths, classified by age and sex, using the Chandrasekaran-Deming formula.

FINDINGS

Overall under-registration of deaths during 2005-2006 was 9.00% (95% confidence interval, CI: 8.95-9.05) for males and 8.36% (95% CI: 8.31-8.41) for females. For both males and females, under-registration decreased as age increased. Under-registration was greatest among people of either sex aged 1-4 years, whereas it was < 10% among people 60 years of age and older, both males and females.

CONCLUSION

These findings provided correction factors that can be used for adjusting mortality data from the registration system.

How big is the Lyme problem? Using novel methods to estimate the true number of Lyme disease cases in British Columbia residents from 1997 to 2008

Lyme disease (LD) is rare in British Columbia (BC) and, despite being a reportable condition since 1994, may be underreported. Here we review all provincial laboratory and clinical databases to determine the number of LD cases reported in BC from 1997 to 2008. We analyzed demographic characteristics of LD cases and used capture-recapture methodology to estimate the true number of cases in BC for this period. From 1997 to 2008, 93 confirmed cases of LD were reported in BC. Conservative capture-recapture estimates place the true number of LD cases in BC during this period at 142 (95% confidence interval: 111-224), indicating up to 40% underreporting of this rare disease. Despite this underreporting, BC continues to have low endemic risk of LD. Strategies are needed to increase both physician awareness and the use of preventive measures in the BC population, including for those traveling to other endemic areas.

Estimating the World Trade Center tower population on September 11, 2001: a capture-recapture approach

I applied the capture-recapture method to estimate the World Trade Center tower population at the time of the September 11, 2001, terrorist attacks. Available lists helped identify 8965 survivors and 2152 confirmed casualties. The capture-recapture model suggested that an additional 4435 survivors were present, putting the total count of all present at 15,552 (95% confidence interval=15,216, 15,897). An accurate estimate represents the potential number at risk for trauma as a result of direct exposure to the events of the day.

Healthcare preferences among lesbians: a focus group analysis

OBJECTIVE

The healthcare needs of lesbians are not well understood. We sought to characterize lesbians' experiences with, and preferences for, women's healthcare.

METHODS

We conducted three age-stratified focus groups (18-29, 30-50, and >50 years) with a total of 22 participants using a semistructured interview guide to elicit lesbians' experiences and preferences. We analyzed transcripts of these audiotaped sessions using the constant comparative method of grounded theory. Community-dwelling women who self-identified as lesbian and responded to advertisements were selected on first-come basis.

RESULTS

Participants voiced experiences and preferences for healthcare that emerged into three themes: desired models of care, desired processes of care, and desired patient-provider relationship. Each theme was further developed into multiple subthemes. Within the subthemes we identified issues that were specific to lesbians and those that were general women's health issues. Participants preferred, but did not always receive, care that is comprehensive in scope, person centered, nondiscriminatory, and inclusive of them as lesbians.

CONCLUSIONS

Healthcare providers, institutions, and society should adopt an inviting, person-centered approach toward lesbians seeking healthcare, assure them access to healthcare information, and establish healthcare delivery systems that take all aspects of health into account.

Women who report having sex with women: British national probability data on prevalence, sexual behaviors, and health outcomes

OBJECTIVES

We estimated the prevalence of same-sex experience among women and compared women reporting sex with women and men and women reporting sex exclusively with women with women reporting sex exclusively with men, in terms of sociodemographics and sexual, reproductive, and general health risk behaviors and outcomes.

METHODS

We used a British probability survey (n=6399 women, aged 16 to 44 years) conducted from 1999 to 2001 with face-to-face interviewing and computer-assisted self-interviewing.

RESULTS

We found that 4.9% of the women reported same-sex partner(s) ever; 2.8% reported sex with women in the past 5 years (n=178); 85.0% of these women also reported male partner(s) in this time. Compared with women who reported sex exclusively with men, women who reported sex with women and men reported significantly greater male partner numbers, unsafe sex, smoking, alcohol consumption, and intravenous drug use and had an increased likelihood of induced abortion and sexually transmitted infection diagnoses (age-adjusted odds ratios=3.07 and 4.41, respectively).

CONCLUSIONS

For women, a history of sex with women may be a marker for increased risk of adverse sexual, reproductive, and general health outcomes compared with women who reported sex exclusively with men. A nonjudgmental review of female patients' sexual history should help practitioners discuss risks that women may face.

A repeated observation approach for estimating the street homeless population

Risks of life on the street caused by inclement weather, harassment, and assault threaten the unsheltered homeless population. We address some challenges of enumerating the street homeless population by testing a novel capture-recapture (CR) estimation approach that models individuals' intermittent daytime visibility. We tested walking and vehicle-based variants of CR in downtown Toronto in March. Estimates that assume individual variability of sighting probabilities are most consistent with our knowledge of the homeless and achieve the most favorable confidence intervals, estimated detection probabilities, and coefficient of variation. Estimation bias from interobserver discrepancies, duplicate counting, and violation of the closed population assumption were minimized with uniform identification criteria, training, and sampling design. Bias caused by the social grouping of the homeless was small. Despite the limitations of visual identification, CR approaches as part of a multiple-method program can aid community responses to immediate needs on the street, especially during the harsh winter months.

Estimating the population of female sex workers in two Chinese cities on the basis of the HIV/AIDS behavioural surveillance approach combined with a multiplier method

OBJECTIVE

To estimate the size of the population of female sex workers (FSWs) on the basis of the HIV/AIDS behavioural surveillance approach in two Chinese cities, using a multiplier method.

METHOD

Relevant questions were inserted into the questionnaires given to two behavioural surveillance groups-female attendees of sexually transmitted disease (STD) clinics and FSWs. The size of the FSW population was derived by multiplying the number of FSWs in selected STD clinics during the study period by the proportion of FSW population who reported having attended the selected STD clinics during the same period.

RESULTS

The size of the FSW population in the urban area of Xingyi, China, was estimated to be about 2500 (95% CI 2000 to 3400). This accounted for 3.6% of the total urban adult female population. There were an estimated 17,500 FSWs in the urban area of Guiyang, China (95% CI 10,300 to 31,900) or about 3.4% of its total urban adult female population (rounded to the nearest 100).

CONCLUSIONS

The multiplier method could be a useful and cost-effective approach to estimate the FSW population, especially suitable in countries where HIV behavioural surveillance has been established in high-risk populations.

A study on methods of estimating the population size of men who have sex with men in Southwest China

OBJECTIVE

To ascertain practical methods of estimating the population size of men who have sex with men (MSM) by field application.

METHODS

Nine public places were selected, where men who have sex with men (MSM) frequented. Capture-recapture method and multiplier method were used to count the number of men who have sex with men (MSM) in the assigned places in 10 days.

RESULTS

The population size estimated using multiplier method counted 877. Three estimates produced by capture-recapture method were 1408 (95% CI: 1116-1908), 1207 (95% CI: 932-1712) and 949 (95% CI: 757-1272), respectively.

CONCLUSIONS

Multiplier method was easy and smooth in practice and produced highly reliable results, which yet was expensive. The application of capture-recapture method cost less in both time and funds, and the three results produced could verify each other, which was fit for the estimation.

Recruiting minority men who have sex with men for HIV research: results from a 4-city campaign

We describe the efforts of a 4-city campaign to recruit Black and Hispanic men who have sex with men into an established HIV epidemiological study. The campaign used community organizing principles and a social marketing model that focused on personnel, location, product, costs and benefits, and promotion. The campaign was developed at the community, group, and individual levels to both increase trust and reduce barriers.The proportion of Hispanic men recruited during the 2002-2003 campaign doubled compared with the 1987 campaign, and the proportion and number of White men decreased by 20%. The proportion of Black men decreased because of the large increase in Hispanic men, although the number of Black men increased by 56%. Successful recruitment included training recruitment specialists, involving knowledgeable minority community members during planning, and having an accessible site with convenient hours.

Counseling lesbian patients about getting pregnant

OBJECTIVE

To describe an approach to counseling lesbian patients about getting pregnant.

SOURCES OF INFORMATION

Information in this paper is based on evidence from randomized controlled trials (level I evidence), non-randomized trials (level II evidence), expert opinion (level III evidence), and government regulations.

MAIN MESSAGE

We review 5 steps that comprise an approach to counseling lesbian patients about getting pregnant safely and efficiently. These steps are preconception care (including counseling, testing, and immunization); donor choice (including explaining the risks and benefits of choosing between a known or anonymous donor and the difference between fresh and frozen semen); donor testing (including Health Canada's requirements for semen processing and recommendations for testing before home insemination); ordering the semen (including information about sperm banks and the need for "Canadian compliant" semen); and the insemination process (including techniques for monitoring ovulation and various methods of insemination).

CONCLUSION

Primary care physicians can help lesbians achieve pregnancy by providing education, testing, referrals, and insemination services.

Multisystem Factors Contributing to Disparities in Preventive Health Care Among Lesbian Women

Lesbians experience significant health disparities in preventive care utilization and health outcomes compared to heterosexual women. In this study, a multisystems ecologic approach is taken to identify barriers to access, treatment, and preventive care among lesbian women. Recommendations include increasing knowledge of lesbian health care needs, developing cultural sensitivity and competence in communication and care for lesbian women, and creating practice environments that convey respect, acceptance, and welcome to all women, regardless of sexual orientation.

Barriers to infectious disease care among lesbians

Despite the considerable number of women in the United States who identify as lesbian, few data exist that address lesbians' health needs. The Institute of Medicine emphasized that data on sexually transmitted infections, Pap smear screening, and cervical dysplasia among lesbians were needed to guide clinical practice, policy development, and patient education. Use of surveillance data for this purpose is limited because risk classifications exclude same-gender sex among women or subsume it under behavior considered as higher risk. However, sexual transmission of human papillomavirus, HIV, Treponema pallidum, and Trichomonas vaginalis between women has been reported. Data indicate that lesbians receive routine Pap smear screening less frequently than is optimal. Moreover, lesbians commonly report previous pregnancy, induced abortion, and hormonal contraceptive use. Education of lesbians and their care providers should counter assumptions that sex between women confers no risk for transmission of sexually transmitted infections, and lesbians should receive Pap smears according to current guidelines.

Assisted reproductive technologies and equity of access issues

In Australia and other countries, certain groups of women have traditionally been denied access to assisted reproductive technologies (ARTs). These typically are single heterosexual women, lesbians, poor women, and those whose ability to rear children is questioned, particularly women with certain disabilities or who are older. The arguments used to justify selection of women for ARTs are most often based on issues such as scarcity of resources, and absence of infertility (in lesbians and single women), or on social concerns: that it "goes against nature"; particular women might not make good mothers; unconventional families are not socially acceptable; or that children of older mothers might be orphaned at an early age. The social, medical, legal, and ethical reasoning that has traditionally promoted this lack of equity in access to ARTs, and whether the criteria used for client deselection are ethically appropriate in any particular case, are explored by this review. In addition, the issues of distribution and just "gatekeeping" practices associated with these sensitive medical services are examined.

Female genital mutilation, asylum seekers and refugees: the need for an integrated European Union agenda

Asylum seekers and refugees (ASRs) are a heterogeneous population with distinct physical and psychological needs. ASRs with additional health needs are girls and women who have undergone, or are at risk of undergoing, female genital mutilation (FGM). Across the European Union (EU), variation exists in Member States' anti-FGM and asylum legislation, the rigour of existing research programmes, and the operational coherence of the multiple agencies combating the practice. ASRs' needs are, consequently, not being addressed satisfactorily. This paper proposes an integrated future agenda, applicable in all EU countries, capable of meeting these girls' and women's needs.

Prevalence of problematic cocaine consumption in a city of southern Europe, using capture-recapture with a single list

This study aims to determine the magnitude and characteristics of problematic cocaine consumption in the city of Barcelona, Spain. Capture-recapture with a single source was used to estimate prevalence. Log-linear regression models with interaction terms were fitted to the total sample and to subgroups according to other drugs consumed. Emergency room indicator data were obtained from the Barcelona Drug Information System. Drug-related emergencies of Barcelona residents for 1999 were analyzed. During 1999, a total of 4,035 drug-related emergencies were seen in Barcelona hospitals. Of these, 1,656 (41%) involved cocaine consumption; 41% of these patients had consumed cocaine with an opiate; 29% used cocaine with other substances; and 30% used cocaine alone. It was estimated that there was a total of 25,988 problematic cocaine users (95% confidence interval 11,782-58,064), yielding a rate of 31.27 per 1,000 inhabitants aged 15 to 54 years (95% confidence interval 14.2-69.9). The number of cocaine-related emergencies was high enough to allow capture-recapture to be applied, thus obtaining an estimate of the prevalence of problematic cocaine consumption, and high enough to characterize users according to different profiles. The use of capture-recapture with a single source can be interesting for problems related to the urban context.