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Prevalence and Predictors of Sexually Transmitted Infection Among Newly Incarcerated Females

Willers, Denise M. MD*; Peipert, Jeffrey F. MD, MPH*; Allsworth, Jenifer E. PhD*; Stein, Michael D. MD; Rose, Jennifer S. PhD; Clarke, Jennifer G. MD, MPH

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Sexually Transmitted Diseases: January 2008 - Volume 35 - Issue 1 - p 68-72
doi: 10.1097/OLQ.0b013e318154bdb2
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SEXUALLY TRANSMITTED INFECTIONS (STIs) are an important public health problem that disproportionately affects incarcerated women when compared with the general female population. The Centers for Disease Control and Prevention (CDC) Sexually Transmitted Disease Surveillance 2005 reports Chlamydia trachomatis rates of 7% and Neisseria gonorrhoeae rates of 3% among women entering 38 adult correctional institutions.1 These rates are much higher than the CDC 2001–2002 National Health and Nutrition Examination Survey data estimating a 1.8% C. trachomatis prevalence and a 0.2% N. gonorrhoeae prevalence among women between the ages of 18 and 40 in the United States.2 These infections carry the risk of acute and long-term complications such as pelvic inflammatory disease, ectopic pregnancy, chronic pelvic pain, and infertility but have also been shown to increase the risk of transmission of human immunodeficiency virus (HIV) by 3-fold.3,4 Diagnosis of STIs may also be delayed as these women may have limited access to health care because of limited resources. Incarceration may represent a unique opportunity to provide health services including STI testing and education to this population.

Several risk factors have been shown to be correlated to increased STIs in the general population. Risks for C. trachomatis or N. gonorrhoeae include young age, more than one sexual partner, inconsistent condom use, prior STI, and black race.5–8 These characteristics are common in the incarcerated population. Additionally, high rates of alcohol, cocaine, and multidrug use are associated with a higher lifetime prevalence of STIs in incarcerated women.9 History of high-risk sexual behaviors, including sex trade and large numbers of male partners as well as prior sexual abuse, are increased in incarcerated females and are associated with higher rates of prior STI.9

Project CONNECT (CONtraceptive Needs Evaluation and Community Transition), a prospective trial to assess the reproductive health needs of incarcerated women and to evaluate the acceptance of contraceptive services offered at a clinic after release versus contraceptive services offered during incarceration, was an evaluation of a federally funded Title X program. The study has found that provision of contraceptive services during incarceration can significantly increase contraceptive initiation compared with community-based services.10,11 Furthermore, Rosengard et al. reported inconsistent condom use in female arrestees in this cohort with only 50% of those with casual partners and 20% of those with a single recent partner reporting condom use.12 This cross-sectional analysis aims to evaluate the baseline prevalence and the demographic and behavioral characteristics of the population enrolled in Project CONNECT to determine those characteristics that are associated with C. trachomatis, N. gonorrhoeae, and Trichomonas vaginalis in incarcerated women.

Materials and Methods

The Rhode Island Adult Correctional Institute (ACI), which serves as both a prison and jail, holds all pretrial and sentenced female inmates in the state. The average daily population is 200, and approximately 1500 women enter the ACI annually; however, 69% of arrestees return to the community within 4 days. Most (79%) of the women at ACI have been charged with nonviolent crimes, including 31% of women charged with drug offenses.

Approval for this study was obtained from the Miriam Hospital Institutional Review Board, the Office for Human Research Protection, as well as the Medical Research Advisory Group at the ACI before study initiation. As this is a vulnerable population, several other protections were placed to ensure the safety and confidentiality of participants. A Certificate of Confidentiality was obtained from the federal government to ensure participant privacy, and the warden of the facility granted permission for all interviews to occur one-on-one with research assistants in unmonitored rooms to further emphasize that the study was separate from the ACI. All consent forms were read aloud to the participants by the research assistants and all questions were answered before consent. It was stressed to the participants that the study would in no way influence parole status, privileges, or the receipt of reproductive health services.

Women, either sentenced or awaiting trial, entering the ACI between June 2002 and December 2003 were recruited for participation in the study. Monday through Friday, research assistants reviewed daily traffic sheets, which included all female inmates committed to or released from the facility. They attempted to contact each woman for participation in the study. Inclusion criteria included English speaking, not housed in segregation, 18 to 35 years old, without prior history of tubal ligation or hysterectomy. Women who were pregnant, had plans to become pregnant within the next 6 months, or who were not competent to give informed consent were excluded.

Demographic, psychosocial, and behavioral characteristics including sexual history, drug or alcohol use, and contraceptive use were collected during a 45-minute face-to-face interview conducted by trained female research interviewers. The participants were asked to self-collect vaginal swabs for N. gonorrhoeae and C. trachomatis, which were tested by polymerase chain reaction, and T. vaginalis by InPouch culture. During the recruitment period, there were 3549 commitments, and 1251 of these represented reincarceration of the same woman, leaving 2298 possible participants. Of these, 707 were released before evaluation, 1212 were ineligible because of age >35 (803) or other exclusions (409), 155 refused to participate, and 19 were missing STI results, leaving 205 participants.

The outcome of interest was a positive result at the baseline evaluation for any of the following: N. gonorrhoeae, C. trachomatis or T. vaginalis. Potential confounders evaluated included age (in years—<25, 25–29, or 30 and older); race/ethnicity (white, non-Hispanic, black, non-Hispanic, Hispanic or other); education (less than high school/GED); sex with a man in the past 3 months; sexual partners in the past year (0–1, 2–5 or 6, or more partners) and lifetime (1–10, 11–20, 21–40, or 40 or more partners); having exchanged sex for drugs or money; current smoker; history of STI; recent hormonal contraceptive use; recent condom use with main or casual partner (lowest frequency of use; no information; inconsistent use; consistent use); recent drug use; history of physical or sexual abuse; and homelessness before incarceration. Potential confounders were identified through review of the literature and bivariate analyses. In our adjusted analyses, we excluded the variable lifetime sexual partners because of correlation with recent sexual partners. Recent sexual partners are a better predictor of STI risk.

Categorical variables were compared using a χ2 test. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated using Poisson regression with robust error variance. This approach was used because the prevalence of STI was over 30% and logistic regression may have overestimated the size of the effect.13 We calculated 2 estimates of RR: a crude estimate and an estimate adjusted for age, race/ethnicity, education, number of partners in the past year, having had sex for drugs or money, and homeless before incarceration. Analyses were performed in SAS (v. 9.1, SAS Institute, Cary, NC).


Demographic characteristics are reported in Table 1. The population included 108 (53%) women aged 24 or younger, 48 (23%) women aged 25 to 29, and 49 (24%) women aged 30 to 35. The population was 50% white, non-Hispanic, 19% black, non-Hispanic, 18% Hispanic, and 11% described themselves as other race/ethnicity. Eighty-six (42%) of the participants had no high school diploma or GED, an additional 80 (39%) had either a GED or high school diploma, and 36 (18%) had some college or a college degree. Eighteen percent of patients were homeless before their incarceration.

Demographic Characteristics of Women With and Without an STI at Baseline

Most women had been sexually active with a man in the 3 months before the study (87%). Sixty-one (30%) had 0 or 1 partner in the past year and 33 (16%) had 6 or more partners in the last year. Ninety-five (46%) of participants had had 10 or less lifetime sexual partners, but 33 (16%) reported 41 or more lifetime sexual partners. Sixty-four percent had a history of physical or sexual abuse. Twenty-seven percent of participants give a history of prior sex for drugs or money. Fifty-eight percent of participants used heroin, cocaine, or other opiates in the last 90 days.

Patients were queried about prior STI and 115 (56%) reported previous infection. Reported past STIs included 83 with N. gonorrhoeae (40%), 46 with T. vaginalis (22%), 3 with syphilis (1.5%), 18 with pelvic inflammatory disease (9%), 14 with condyloma (7%), and 3 reported genital herpes (1.5%). Only one woman reported HIV infection.

Sixty-eight of 205 patients tested positive for STI (33%; 95% CI 27%–40%). Forty-five participants (22%) had T. vaginalis. Twenty-seven (13%) were infected with C. trachomatis and 21 (10%) were infected with N. gonorrhoeae. Twenty-one women were infected with 2 or 3 STI. Three women were positive for N. gonorrhoeae and T. vaginalis, 10 were positive for C. trachomatis and T. vaginalis, and 4 were positive for C. trachomatis and N. gonorrhoeae. Four women were positive for C. trachomatis, N. gonorrhoeae, and T. vaginalis.

There was no statistically significant difference between different age groups and STIs. C. trachomatis infection was found in 15% (16 of 105) of women aged less than 25, 17% (8 of 47) of women aged 25 to 29, and 6% (3 of 48) of women aged 30 to 35 (5 missing information). N. gonorrhoeae was detected in 10% (10 of 104) of women aged less than 25, 9% (4 of 47) of women aged 25 to 29, and 14% (7 of 49) of women aged 30 to 35 (5 missing information). T. vaginalis was detected in 27% (25 of 93) of women age less than 25, 33% (13 of 39) of women aged 25 to 29, and 16% (7 of 43) of women aged 30 to 35 (30 missing information).

Crude and adjusted risks are reported in Table 2. In crude analyses, women with 6 or more partners in the past year (RR = 1.84, 95% CI 1.01–3.36) or those who reported 21 to 40 lifetime partners (RR = 2.24, 95% CI 1.02–4.97) had higher risk of STI than those in the lowest category of number of sexual partners. Women with a history of sex for drugs or money were more likely to have an STI (RR = 1.65, 95% CI 1.01–2.69). Participants who described themselves as homeless before incarceration had approximately double the risk of STI (RR = 1.82, 95% CI 1.07–3.09) compared with those who were not homeless. In a fully adjusted model that included age, race/ethnicity, and education, these risks remained elevated, but did not reach the level of statistical significance.

Crude and Adjusted Relative Risks for STI at Baseline


The prevalence of STI in this population was very high, with one-third testing positive for C. trachomatis, N. gonorrhoeae, or T. vaginalis. The C. trachomatis rate of 13% in this study is higher than the 2005 CDC Chlamydia surveillance report with 8.9% C. trachomatis rate in women in adult correctional facilities.1 The N. gonorrhoeae rate of 10% is much higher than the 3.9% rate reported to the CDC from 33 adult facilities throughout the United States in 2005. These differences may reflect the exclusion of patients greater than age 35 in this study, but our highest rate by age for N. gonorrhoeae was 14% in the 30 to 35 age group. Another possibility for the high rates of STI in our population is geographic variations and variation by facility. The CDC report on N. gonorrhoeae includes 20 states including 4 states that reported <1% prevalence and 8 states that reported greater than 4% N. gonorrhoeae rates.1 The highest reported was a facility in California that reported a N. gonorrhoeae rate of almost 14%; yet another California facility reported only a 1% N. gonorrhoeae rate. The range in C. trachomatis by state was 3% to 20% positivity in females in adult corrections facilities.1 There are no similar data on T. vaginalis rates, but the rate of 27% in this study is substantial. Further research to assess patients over age 35 and additional facilities should be undertaken to evaluate the need for and effects of a universal screening policy for T. vaginalis, N. gonorrhoeae, and C. trachomatis.

A study assessing screening of men and women entering US city and county jails in 1997 found that most facilities tested for STI only if arrestees had symptoms and that screening in these facilities ranged between 0.2% and 6% of arrestees. For facilities offering routine testing, between 3% and 45% of arrestees were being screened for STI.14 The National Commission on Correctional Health Care updated their position on women’s health care in correctional facilities in 2005. They recommend that correctional facilities offer STI testing including N. gonorrhoeae, C. trachomatis, and syphilis to all women.15

A recent study evaluated the cost-effectiveness of universal screening for C. trachomatis and N. gonorrhoeae in 2 federal women’s prisons and found that the prevalence of N. gonorrhoeae (0.1%) and C. trachomatis (1.9%) in this population is much lower than previously reported.16 Age 18 to 22 was associated with a 6-fold increased risk of C. trachomatis infection when compared with older women. This study concluded that screening for C. trachomatis in inmates aged 30 and under at the 2 prisons would diagnose approximately 60% of infections and would be cost-effective. Given the low rate of N. gonorrhoeae in the study, screening was not found to be cost-effective. The authors suggest that the ease of screening for both simultaneously should lead to consideration of screening for N. gonorrhoeae as well. The prevalence of C. trachomatis and N. gonorrhoeae in the 2 federal prisons was significantly lower than in our population and the CDC report on facilities by state, and may reflect screening and treatment occurring during initial incarceration before transfer to federal prison.

The CDC recommends annual screening for all sexually active women aged 25 and younger for C. trachomatis and screening of high-risk women for N. gonorrhoeae.17 Several studies have reported younger age as a primary risk factor for STI and C. trachomatis rates for incarcerated adolescent females have been reported as high as 24.7%.16,18–20 The high prevalence among all groups less than age 35 in our study was an unusual finding compared with other studies. We included a jail and prison population and patients aged 25 to 29 had the highest prevalence of STI at 42%. Women less than 25 had a prevalence of 33%. Older women had lower prevalence, but the rate remained very high with 25% of women aged 30 to 35 being infected with an STI. There was a very high rate of N. gonorrhoeae in this age group of 14% and a T. vaginalis rate of 16%.

Other previously reported risks for STI including race, condom use with main and casual partners, number of sexual partners, and prior STI were not statistically significant factors in this study. Additionally, behavioral characteristics may be difficult to obtain confidentially and accurately in a prison population outside of the setting of a research project. The high prevalence and lack of identifiable risk factors suggest that universal screening for N. gonorrhoeae, C. trachomatis, and T. vaginalis in this high-risk population may be appropriate. The link between N. gonorrhoeae and C. trachomatis and pelvic inflammatory disease is well established. There is also some evidence that T. vaginalis is associated with and may contribute to pelvic inflammatory disease21 and has been associated with HIV transmission.22 Further research to evaluate the effects of screening for T. vaginalis would be helpful.

Limitations of this study include release of a large portion of the population before evaluation. This is a secondary analysis of a contraceptive study and limiting the population to those less than age 35 and at risk for pregnancy may decrease the generalizability of the results and introduce selection bias. Additionally, 41% of the candidates for the study refused participation in Project CONNECT. The reasons for refusal were not collected for these inmates, but those who declined participation were similar in age and race to those who agreed to participate. These factors may lead to selection bias and limit the ability to detect subtle associations.

Strengths of this study include evaluation of an understudied population with a very high STI prevalence rate. Another strength is the inclusion of T. vaginalis infection. T. vaginalis infection is understudied in the incarcerated population and this study shows that T. vaginalis infection is very common. Also, the use of self-collected vaginal swabs as used in our study has been shown to be reliable and preferred among patient populations.23–25 As cost is a common argument against universal screening for STI, this method of testing would limit the cost of screening by limiting healthcare provider involvement.

The study highlights the ineffectiveness of screening incarcerated women for STI based on their demographic and behavioral characteristics and gives weight to the argument for routine screening. In our population in which 69% return to the community within 4 days, testing with rapid results are important for treatment before release. This would allow for observed therapy and ensure compliance with treatment as well as ensure that appropriate counseling was provided. Identification and treatment of STI in this high-risk group may help to limit further infections and may improve the overall health of the community.


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