Black and Mexican American women who participated in ethnically tailored behavioral interventions to prevent sexually transmitted disease (STD) had lower risks of subsequently acquiring gonorrhea or chlamydia than those receiving usual counseling in a randomized study in Texas.1 Although the interventions lasted no more than months, participants sustained a 50% reduction in the odds of infection over two years. Women in the intervention groups also were less likely than their counterparts in the control group to have multiple partners or to have unprotected intercourse with an untreated or incompletely treated partner—two risky behaviors that were related to higher rates of infection.
Minority women visiting public health clinics in San Antonio were eligible for the study if they had a nonviral STD (gonorrhea, chlamydia, syphilis or trichomoniasis), spoke English and were 15–45 years old. Women were enrolled in the study between March 1996 and June 1998, within one month of treatment. All received 15–20 minutes of individual STD counseling. They were then assigned to a control group (no intervention), a group given a behavioral intervention (three weekly small-group sessions tailored according to ethnographic data and conducted by female facilitators of the same ethnicity, each lasting three hours) or a group given an enhanced behavioral intervention (the standard intervention plus five optional monthly support group sessions, each lasting 90 minutes). The interventions emphasized assessing one's own risk of acquiring STDs, adopting healthy behavior and seeking care for suspected infections. Six months, one year and two years after starting the study, the women were interviewed and had a physical examination with screening for infections; screenings and diagnoses at other clinics were also ascertained.
Analyses were based on 775 women. Most (80%) were younger than 25. Three-fourths were Mexican American, and one-fourth were black. Fewer than 10% were married, and roughly two-thirds had had more than one sexual partner in the past year. On average, the women had had 11 years of education, and monthly per capita income was about $300. The control group differed from the intervention groups on a number of STD risk factors. Notably, significantly smaller proportions of women in the control group than of those receiving an intervention were teenagers (46% vs. 55–58%), had chlamydia infection (73% vs. 79–82%) and had at least two STD screenings beyond those routinely provided in the study (22% vs. 35–37%). According to women's reports of their alcohol and drug use, roughly one-third had a high or ultrahigh risk of substance abuse; women in the control group were the most likely to have a low or moderate risk, and the least likely to have an ultrahigh risk.
An initial analysis revealed that the two-year cumulative rate of infection with gonorrhea or chlamydia increased steadily from 29% among women with a low or moderate risk of substance abuse to 74% among those with an ultrahigh risk. Thus, the researchers conducted an analysis of STD infection stratified by substance abuse risk. In this analysis, the interventions were associated with reduced odds of infection only for women with a low or moderate risk of substance abuse (odds ratio, 0.4 for each intervention).
In the study group overall, cumulative two-year rates of gonorrhea or chlamydia infection, adjusted for substance abuse risk and other risk factors, were 40% in the control group and 24–26% in the intervention groups. The differences corresponded to a 50% reduction in odds among women in the intervention groups (odds ratio, 0.5 for each). Similar reductions in odds occurred during the first year (0.5 for each) and during the second year (0.6 for each) individually.
Within the enhanced intervention group, 37% of women attended at least one of the optional support group sessions. The two-year rate of infection was 22% among support group attendees and 25% among nonattendees; corresponding reductions in the likelihood of infection relative to women in the control group amounted to 50% or more (odds ratios, 0.4 and 0.5, respectively). Among attendees, the benefit decreased somewhat between the first and second years.
In the control group, 17% of women had an infection diagnosed at least once during the two-year period; by contrast, the proportion was only 8% in the standard intervention group and 7% among women receiving the enhanced intervention. The odds of this outcome were reduced in the intervention groups (odds ratios, 0.5 and 0.4, respectively). Within the enhanced intervention group, the rate of repeat infections was 6% among support group attendees and 8% among nonattendees; again, odds were reduced by at least half when compared with odds for the control group (0.4 and 0.5).
Women who engaged in unprotected sex with a partner who was untreated or incompletely treated were more likely to become infected than women who did not (38% vs. 22%). This risky behavior was less prevalent in the intervention groups (8–10%) than in the control group (18%). Similarly, women who had more than one sexual partner during the study were more likely to become infected than those who had one or none (47% vs. 16%). This risky behavior was likewise less prevalent in the intervention groups (63–69%) than in the control group (76%). Within the enhanced intervention group, rates of both risky behaviors were somewhat lower among support group attendees than among nonattendees.
Overall, the two interventions were similarly effective for preventing gonorrhea and chlamydia, the researchers assert. They note that the added benefit of support group attendance lessened over time, underscoring the importance of both removing barriers to attendance and offering "continuing or booster meetings." The researchers conclude that although changes in rates of HIV infection could not be reliably assessed in the study, and evidence directly linking STD and HIV prevention is lacking, "behavioral risk reduction that disrupts heterosexual transmission of bacterial pathogens could also prevent heterosexual transmission of HIV."—S. London
1. Shain RN et al., Prevention of gonorrhea and chlamydia through behavioral intervention: results of a two-year controlled randomized trial in minority women, Sexually Transmitted Diseases, 2004, 31(7):401–408.