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Prevention of Sexually Transmitted Diseases and HIV in Young Military Men: Evaluation of a Cognitive–Behavioral Skills-Building Intervention


Sexually Transmitted Diseases: June 2001 - Volume 28 - Issue 6 - p 349-355

Background Military personnel deployed to foreign countries with high endemic rates of sexually transmitted diseases (STDs) are at risk.

Goal To evaluate a cognitive-behavioral, skills-building intervention to prevent STDs in junior, enlisted, male US Marines deployed to the Western Pacific aboard ships with periodic liberty visits to foreign ports.

Study Design This study, using a quasi-experimental design, assigned 584 men to a cardiopulmonary resuscitation training (n = 288) or a cognitive-behavioral intervention (n = 296). The intervention aimed to increase prevention knowledge, reduce high-risk psychosocial (motivation) factors, and build decision-making and communication skills to reduce risky sexual behaviors and alcohol consumption.

Results Participation in the intervention was associated with increased knowledge regarding symptoms and treatment of STDs and HIV (P < 0.001), decreased alcohol use (P < 0.01), and sexual risk (P < 0.01) during liberty ports of call.

Conclusion A multiple-session, cognitive-behavioral, skills-building intervention can be successfully implemented for deployed military personnel.

From the Departments of *Pediatrics and ‡Laboratory Medicine, University of California, San Francisco, California; and †Naval Health Research Center, San Diego, California

Supported by the National Institutes of Health, National Institutes of Allergy and Infectious Diseases, STD Branch (grant number A131499–01); the National Institutes of Allergy and Infectious Diseases Initiatives for Underrepresented Minorities in Biomedical Research Supplement (grant number U01-A131499–0353), which supported Dr. Boyer; the United States Navy Research and Development Command (work unit number 6E3301 63106A-0101-KHX-E406); and the Maternal and Child Health Bureau (grant number MCJ000978), which partly supported Drs. Boyer and Shafer.

The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the United States Government.

The authors thank Shannon Putnam, Steven Wignall, Jeanne Moncada, David Brooks, Michael Spokane, Myra Young, and Priscilla Lee Chu for their assistance with this project. They also thank Courtney Abrams, Gary Woodford, Al Hunt, Gerald Mante, John Andrews, Lonnie Hawkins, James Clarke, Graydon Webster, and Al Figer for their dedication and hard work in implementing this study aboard the ships.

Reprint requests: Cherrie B. Boyer, PhD, Department of Pediatrics, Division of Adolescent Medicine, University of California, San Francisco, 3333 California Street, Box 0503, San Francisco, CA 94143-0503. E-mail:

Received for publication March 1, 2000, revised October 3, 2000, and accepted November 7, 2000.

Participation of male, junior enlisted Marines in an STD/HIV prevention intervention was associated with increased knowledge regarding STD/HIV symptoms and treatment, decreased alcohol use, and sexual risk during liberty ports of call.

SEXUALLY TRANSMITTED DISEASES (STDs) still are prevalent in certain populations of the United States. 1–5 The military, populated predominantly with young men, is at high risk for STDs, particularly when deployed to foreign countries with high endemic rates of sexually transmitted conditions, including HIV. 6–8 Previous studies of deployed military personnel have documented a number of factors contributing to STD acquisition including sexual contact with commercial sex workers, abuse of alcohol, and inconsistent use of condoms. 6,9 Increasing drug resistance and the threat of HIV have resulted in a renewed emphasis on primary prevention of STDs in military personnel.

Research has shown that STD/HIV prevention interventions based on cognitive-behavioral principles are effective strategies for building skills and modifying behaviors associated with STDs and HIV infections in various populations. 10–17 However, none of the studies have involved active-duty, male, military personnel. A deployed military unit provides a well-defined population with known periods of risk during liberty ports of call. This article reports the feasibility and evaluation of a cognitive-behavioral intervention designed to reach this population.

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Study Design

Active-duty, male, enlisted, US Marines in a five-ship assault ready group (ARG) deployed to the Western Pacific from January to June 1994 were recruited to participate in this study during the first week of deployment. In a quasi-experimental design, participants on the largest ship were assigned to the experimental intervention, and participants on three support ships were assigned to cardiopulmonary resuscitation (CPR) training, the control condition.

After signed informed consent, volunteers completed a self-report questionnaire and had urine and blood collected for STD screening during the first week of deployment aboard the ships. The experimental and control interventions were conducted before arrival at the first liberty port, with a booster session conducted for each group at mid-deployment. Posttest questionnaires and STD screening (follow-up evaluation) were collected 6 months later, at the end of deployment, before arrival at the home port.

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The Experimental Intervention

The experimental intervention consisted of four 2-hour, multicomponent, interactive group sessions involving 20 to 25 men, facilitated by trained Navy corpsmen, with a 2-hour booster session. The CPR control condition was a single 8-hour session with a mid-deployment booster.

The intervention focused on key elements of the information, motivation, and behavioral skills model 18,19 as applied to HIV and STDs because they are prevalent in young sexually active men. 2–4,20 Specific goals included increase of knowledge, prevention or reduction of STD/HIV-related risk factors (e.g., alcohol use) and their associated psychosocial antecedents, the building of effective decision-making and communication skills. Table 1 provides an overview of the intervention.

Table 1

Table 1

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Self-report questionnaires.

Development of the pre- and posttest questionnaires was guided by constructs of the information, motivation, and behavioral skills model and included sociodemographic factors (e.g., age, race and ethnicity, marital status, number of prior deployments), clinical factors (e.g., history of STDs), and behavioral risk (e.g., alcohol use and sexual risk).

Alcohol use assessed the quantity and frequency of alcohol use during each liberty day in port. The participants were categorized into one of three alcohol use categories: nondrinker (no alcohol use), light or moderate drinker (1 to 4 drinks per liberty day or 5 drinks or more on fewer than half of the liberty days), or heavy drinker (5 or more drinks on at least half of the liberty days).

Sexual risk was assessed by a 3-point, categorical index that accounted for the number of partners with whom the participants had sexual intercourse and their use of condoms during liberty visits. The participants were categorized into one of three sexual risk categories: no sexual risk (no sex during liberty visits), low sexual risk (1 partner per liberty port of call and consistent condom use), or high sexual risk (1 or more partners and/or inconsistent condom use).

Information (knowledge) was assessed using “true,” “false,” and “don’t know” composite indices, and motivation variables were composite indices scaled on 5-point Likert scales. This part of the questionnaire included the following subscales:

  • STD/HIV Transmission Knowledge: 12 items that assessed the participants’ knowledge of STD/HIV and AIDS (mean = 10.1 ± 1.5)
  • STD/HIV Treatment Outcome Knowledge: 11 items that measured basic clinical knowledge of STDs, possible treatments, and outcomes (mean = 6.0 ± 2.2).
  • Perceptions of Risk for STD/AIDS: 2 items that determined the extent to which participants perceived themselves to be at risk for STDs/HIV (mean = 0.9 ± 1.4; Cronbach’s alpha = 0.84)
  • Negative Attitudes about Using Condoms: 4 items that assessed the extent to which participants perceived that condoms interfered with sexual pleasure (mean = 7.3 ± 3.7; alpha = 0.78)
  • Perceptions of Self-Efficacy for Using Condoms: 3 items that measured the extent to which participants perceived they could use condoms effectively (mean = 8.7 ± 2.6; alpha = 0.61)
  • Intention to Engage in Prevention Behaviors: 6 items that determined the participants’ intention to engage in behaviors that prevented STDs/HIV during liberty visits (mean = 10.8 ± 4.2; alpha = 0.61)
  • Negative Peer Perceptions of STD Risk: 3 items that measured the participants’ subjective perceptions of peers’ misconceptions about STDs (mean = 2.8 ± 2.2; alpha = 0.61).

Behavioral skills were measured using the participants’ written responses to vignettes describing simulated risky situations. One vignette focused on the participant’s alcohol use prevention skills in making decisions about whether to continue drinking in a social situation and about communicating with his peers regarding his decision. The responses to this vignette ranged from 1 (unskilled response: a willingness to go along with whatever friends do and to continue drinking despite a sense of having had enough to drink) to 4 (highly skilled response: emphatic decision to stop drinking based on knowing that enough drink has been consumed and encouragement to his friends to do likewise).

Another vignette focused on sexual risk prevention, assessing the participant’s ability to communicate with a potential new sexual partner regarding STD concerns and the importance of discussing one’s sexual history and safer sex strategies. This vignette was coded the same as the alcohol use prevention skills vignette.

Two trained research assistants independently coded and rated the qualitative skills data. The correlation between the two independent ratings was 0.84 for the alcohol use prevention skills vignette and 0.86 for the sexual risk prevention skills vignette.

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STD screening—first-void urine specimen.

The first 15 ml of urine was collected, prepared for transport in the ship’s medical clinic, and sent directly to a university-based laboratory for processing. All the specimens were processed in batches using chlamydial and gonococcal amplified DNA tests (ligase chain reaction) according to the manufacturer’s directions (Abbott Laboratories, Chicago, IL). 21 All the participants who had a diagnosed chlamydial or gonorrheal infection at baseline were given standard treatment, 22 and infections detected at baseline were treated before the first port of call.

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STD screening—serology.

Sera were screened with a venereal disease research laboratory test for syphilis and a second-generation enzyme immunoassay (EIA; Abbott Laboratories) for antibody to HIV. Any sera with a positive EIA for HIV had confirmatory serologic screening with Western blot analysis, and seroconversion was confirmed with a negative baseline p24 antigen (EIA; Abbott Laboratories). Hepatitis B was detected with an EIA (Abbott Laboratories) for total antibody to hepatitis B core antigen (anti-HBc) at baseline and IgM anti-HBc at late deployment.

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Sample Size Considerations

A sample size of 270 study participants per group was calculated by decreasing the proportion of study participants in the intervention group categorized as high sexual risk during liberty visits from 25% to 15%. All analyses were based on a Cronbach alpha of 0.05 (two-tailed) and a power of 0.80.

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Data Analyses

Baseline characteristics were compared by t test for differences in means and χ2 for differences in proportions using an SAS statistical software package, release 6.09 (SAS Institute, Inc., Cary, NC;Table 2). Group differences in sexual risk and alcohol use during liberty ports of call were compared using χ2 (Figure 1). Polychotomous logistic regression analyses to assess the effect of group assignment on the three levels of sexual risk and the three levels of alcohol use were performed, with control used for sociodemographic factors that differed significantly between the two groups at baseline (Table 3). Multiple linear regression analyses were used to assess the effect of group assignment individually on each of the information, motivation, and behavioral skills variables, after control for corresponding baseline measures of these indices.

Table 2

Table 2

Fig. 1

Fig. 1

Table 3

Table 3

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Characteristics of the Study Participants

Work details permitted 686 (67%) of the 1028 junior enlisted Marines to be available during periods of recruitment, and 619 (91%) agreed to participate. Of the 313 intervention participants, 275 (88%) completed both questionnaires and attended the four initial intervention sessions as well as a booster; 288 (94%) control participants completed pre- and posttest questionnaires and attended the single 8-hour CPR session as well as a mid-deployment booster session on first aid. Table 1 summarizes the demographics, behavioral characteristics, and STD findings of the study participants at baseline.

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Behavioral Outcomes

An assessment of group differences in the use of alcohol during liberty ports of call showed that the intervention group participants, as compared with the control group participants, were significantly more likely to be nondrinkers (23.3% versus 13.2%) or light/moderate drinkers (35.8% versus 28.5%) than heavy drinkers (40.9% versus 58.3%; χ2 = 19.6;P < 0.001;Figure 1 A). As a further assessment of group differences in the use of alcohol during liberty visits, a logistic regression model for polychotomous data showed that after control for the effect of marital status, pay grade, and deployment in the previous 5 years, the intervention had an independent and significant effect on alcohol use. Specifically, as compared with the control group, the intervention group participants were significantly less likely to be heavy drinkers (Table 3).

A comparison of group differences in sexual risk during liberty visits indicated that the intervention group participants were significantly more likely to be at no sexual risk (65.2% versus 4.5%) than the low (19% versus 28.5%) or high (15.9% versus 26%) sexual risk participants (χ2 = 22.8;P < 0.001;Figure 1 B). Moreover, a logistic regression model used to assess the effect of the intervention on sexual risk behavior during liberty visits showed that after control for marital status, pay grade, and previous deployment, the intervention had an independent and significant effect on sexual risk. That is, as compared with the control group, the intervention group participants were significantly less likely to be at either low or high sexual risk. Marital status was also significantly associated with sexual risk. Single men were more likely to be at low or high sexual risk than married men (Table 3).

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Information, Motivation, and Behavioral Skills Outcomes

After control for each corresponding baseline measure and group assignment, participants in the intervention group showed a higher level of STD/HIV symptom and treatment knowledge (standardized regression coefficient [SRC] = 0.30;P < 0.001), more negative attitudes about using condoms (SRC = 0.12;P < 0.01), and perceptions of low self-efficacy for using condoms (SRC = −0.19;P < 0.001).

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STD Outcomes

All the participants received doxycycline (100 mg daily) as a prophylaxis against malaria. Therefore, STD acquisition could not be assessed accurately. At posttest, asymptomatic chlamydial and gonorrheal infections were documented in the intervention and control group participants, respectively, as 1.1% versus 0.3% and 0.3% versus 0%. There were no hepatitis B virus seroconverters or positive syphilis serologies. One control participant seroconverted to HIV.

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This study showed that an STD/HIV prevention, cognitive-behavioral, skills-building intervention with multiple sessions can be implemented and well received by deployed military personnel. Although the use of malaria prophylaxis with doxycycline precluded an evaluation of the intervention effect on STD acquisition, the intervention group participants reported significantly lower use of alcohol and sexual risk during liberty ports of call.

These findings hold important implications because deployed military personnel are at increased risk of acquiring STDs, 6–8 which was exemplified by one control group participant’s acquisition of HIV. A decrease in the use of alcohol during liberty visits may not only reduce the risk for STDs, but may also have an impact on other serious consequences of heavy alcohol use, such as time lost from work and motor vehicle accidents.

Participation in the intervention group was not associated with a significantly higher level of STD/HIV transmission and prevention knowledge. This may reflect a ceiling effect because knowledge levels in both groups were already high at baseline, allowing very little room for improvement. This is consistent with findings from other research among military personnel. 23 In contrast, the intervention participants reported a significant higher level of STD/HIV symptom and treatment knowledge.

According to the information, motivation, and behavioral skills model, psychosocial factors (motivation) such as perception of risk and perceived peer norms are important contributing factors for engaging in preventive behaviors. The findings from this study suggest that the intervention did not clearly or consistently influence motivation or behavioral skill factors. This result may be attributed to the strong emphasis on behavioral risk factors during liberty visits, with less emphasis on the more subtle factors of beliefs and attitudes.

An unexpected finding was that the study participants in the intervention group had more negative attitudes about using condoms and perceptions of low self-efficacy for using condoms. This possibly reflects increased knowledge because both the limitations and advantages of condom use were stressed in the intervention.

The intervention group participants reported a higher rate of sexual abstention than the control group participants. However, this finding needs to be explored further with future research.

Overall, this study demonstrated that a multicomponent intervention designed for the prevention of STDs/HIV is a feasible and practical approach for educating deployed military personnel. Currently, 1 hour of didactic HIV/STD prevention education is required. Moreover, it has been shown that noninvasive screening and treatment of asymptomatic STDs also are possible in remote settings. This has implications not only for the infected individual, but also for spouses, offspring, and future sexual partners.

The limitations of this study should be noted also. The nature of the shipboard setting, with study participants living and working together in confined spaces, forced the use of a quasi-experimental study design to avoid potential transmission of information. This could have increased potential bias resulting from nonrandomization. Therefore, the results should be interpreted with some degree of caution. In addition, because the questionnaire was a self-report instrument, the veracity of the study participants’ responses may be questioned. However, precautionary steps were taken to increase the participants’ willingness to answer each question as honestly as possible, including the use of intervention facilitators who were not a part of the ship’s staff and the assurance of confidentiality. Despite these limitations, the findings suggest that implementation and evaluation of such interventions are possible in other nonclinical settings such as community residential programs, correctional facilities, and nondeployed military forces.

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