The first model shows that women aged 25 to 29 years are at a significantly higher risk of being HIV-positive than women in the reference category aging from 15 to 19 years. Those living in Nyanza are more than twice as likely as those living in Nairobi to be HIV-positive, whereas the risk for contracting HIV is much lower in North Eastern Province than in Nairobi. Those living in rural areas are half as likely to be positive as those in urban areas. The number of one's children that has died is clearly associated with being HIV-positive: compared with those who have never had any children, those who have experienced the death of 1 child are twice as likely to be HIV-positive, whereas those who have experienced the loss of 2 or more of their children are more than 3 times as likely to be infected.
In the second model, the addition of a variable indicating age at first sex, although not significant itself, clarifies the age-related risks for being HIV-positive: results indicate an inverted U-shaped relationship between age and infection, with the probability of being infected with HIV peaking at age 25 to 29 years. The risk for those living in Nyanza remains double that of Nairobi, whereas rural residence has lost its significant protective effect as a result of controlling for wealth. Those with primary education are nearly twice as likely to be HIV-positive as those with no education; although the odds for being HIV-positive are higher for the secondary and higher education categories, they are not significantly different than those for people with no education.
Wealth is positively and monotonically related to being HIV-positive, with those in the wealthiest quintile being 3 times more likely to be infected than those in the poorest quintile. Regarding marital status, widowed women are nearly 10½ times more likely to be HIV-positive, women who are 1 of 3 or more wives in a polygynous marriage are over 3 times more likely to be HIV-positive, and women who are divorced or separated are about 2½ times more likely to be infected compared with women who are the only wife in a marital or cohabitating union. Never-married women are no more or less likely to be infected than the reference group. Muslim women are 70% less likely than women of other religions to be HIV-positive. One's perceived risk of contracting HIV remains related to HIV serostatus; however, the results differ from the bivariate once demographic factors are controlled for: only women who believe they have a small risk of contracting the virus are more likely, by approximately 50%, to be HIV-positive than those that believe they have no risk at all for contracting the virus.
The third model incorporates 3 biological variables: whether a woman has given birth in the 5 years preceding the survey, whether a woman reports having an STI in the past year, and whether a woman is currently using either DMPA or Norplant as a contraceptive method. Women who have had a birth in the 5 years preceding the survey are approximately 30% less likely to be HIV-positive than those who did not have a birth in the past 5 years (P = 0.033); note that the bivariate relationship did not show significance, and adjustment for other factors makes the relationship stronger. Women who report having had an STI in the year preceding the survey are 80% more likely to be HIV-positive than women who did not. Use of DMPA/Norplant was not a significant contributing factor.
The final model incorporates key risk behaviors into the analysis. Due to failure to improve model fit and lack of significance, the variables reflecting ever-use of condoms and ever-exchange of sex for goods or money have been excluded from the final model. The risk of being HIV-positive does not vary according to reported number of partners in the past year. There are higher risks for women who have ever consumed alcohol compared with women who report that they never have: although the risks for being HIV-positive are 50% higher for women who have ever drunk alcohol but have not done so in the past month (P = 0.055), they are 2½ times higher for women who have drunk alcohol on 1 to 2 days in the past month (P = 0.006). Surprisingly, women who have drunk alcohol on 3 or more days in the past month are not significantly more likely than women who never drink to be HIV-positive. Relationships among the other variables in the model vary little with the addition of these 2 behavioral factors, with 1 exception: upon controlling for the number of partners a woman has had in the past year, the odds that a widow is HIV-positive compared with women in a monogamous union increase from approximately 10 times the risk to nearly 11 times the risk. No other category of marital status is affected by the control for number of partners.
In the first model for the men's analysis, we note the inverted U-shaped relationship between age and infection with HIV, such that those in the ages ranging from 25 to 44 years are the most likely to be infected, with risk peaking for those in the ages 35 to 39 years. All age groups are more likely to be infected than the reference group (ages 15-19 years). As discussed for the women's analysis, those living in Nyanza have a risk of being HIV-positive that is 3½ times greater than that for those living in Nairobi, the reference region. Men living in rural areas had a 57% reduced risk for being HIV-positive; unlike in the women's analysis, the protective effect of rural residence remains in the final model. The probability of being HIV-positive is positively, but not significantly, related to the number of one's children that has died.
The second model incorporates a number of social characteristics, most of which are not significant. Age at first sex does not have a significant relationship with HIV-serostatus in the multivariate analysis. The addition of the wealth variable, although not significant, results in the loss of the protective effect of rural residence. Religion is also a significant factor, with those reporting that they are not affiliated with a particular religion being nearly 2½ times as likely to be HIV-positive as Roman Catholics. As noted in the women's models, those who believe themselves to have only a small risk of contracting HIV are, in fact, more likely to be infected than those who believe they have no risk of infection at all.
In the third model, we find that reporting an STI in the past year is not significantly related to HIV serostatus for men, in contrast to what was found for women. However, the variable reflecting circumcision status is among the strongest in the model: men who are circumcised have one quarter the risk of those who are not circumcised to be HIV-positive. The circumcision variable absorbs most of the influence of STIs on the likelihood of being HIV-positive; number of partners in the past year also absorbs some of the influence of STIs.
The fourth model incorporates behavioral risk factors. The number of sexual partners in the past year does not have a significant relationship to HIV serostatus. Those who drank alcohol on 11 to 19 days in the past month were more than 2½ times as likely to be HIV-positive as those who have never consumed alcohol; otherwise, HIV status varies little by alcohol consumption. Those who did travel away from home were no more or less likely to be HIV-positive than those who did not, with the exception of those who reported staying away from home 11 or more times; these respondents were 78% more likely to be HIV-positive (P = 0.076).
In an effort to improve our understanding of the HIV/AIDS epidemic in sub-Saharan Africa, in general, and in Kenya, in particular, this study has reported on national HIV seroprevalence in Kenya and assessed key variables for their association with HIV serostatus at the individual level. The most important demographic, social, biological, and behavioral factors and their programmatic implications are discussed below.
The key demographic factor in this analysis was region: both men and women from Nyanza Province had double the risk for infection with HIV as compared with the respondents from Nairobi, the most densely-populated area in Kenya. Rural residence did not exert a protective effect on the risk of contracting HIV among women, and did so only weakly among men (P = 0.074), echoing findings of other researchers (eg, Voeten et al21) who show that sexual behavior can be significantly riskier in rural areas. Although many researchers regard urban residence as a key risk marker, the potential for HIV spread in rural areas exists; HIV/AIDS education and VCT services must reach rural residents.
Wealth was positively related to risk for HIV for both men and women, yet education did not show the same relationship to the outcome variable. Because economic status and educational status typically correlate for many outcomes, this finding is intriguing and would benefit from further exploration. Respondents who think they have only a small risk of contracting HIV are, in fact, at highest risk of being HIV-positive, compared with those who think they have no risk. Such findings highlight the crucial importance of getting tested to know one's status: those who believe themselves to have only a small risk are unlikely to take steps to prevent further transmission of the virus.
Marital status proved to be a significant risk factor for women, in particular widowed and divorced statuses. Wife inheritance (the remarriage of a widow to the brother or other male relative of the deceased husband) is a custom that is widespread in western Kenya, particularly among the Luo,22 who are concentrated in Nyanza Province. Given that widows are at extremely high risk of being HIV-positive, should they remarry, their new spouse takes on that increased risk for acquiring the virus. The fact that wife inheritance is widely practiced among the Luo people, in accordance with the fact that Luo men are the least likely among all Kenyans to have been circumcised,23 seems to be a lethal combination in the context of HIV/AIDS.
Women with HIV were 30% less likely to have recently given birth, results that are congruent with the findings of previous studies.16 Because age and current marital status are controlled for, the association between subfertility and HIV serostatus is most likely to arise from the effect of the virus on a woman's biological susceptibility to becoming pregnant. As expected, women who reported a probable STI were significantly more likely to be HIV-positive than women who reported no STIs in the past year. This finding highlights opportunities for interventions at treating health care facilities: those who test positive for an STI should be screened for HIV, and counseled and treated for their condition(s).
The outstanding biological factor associated with being HIV-positive for men was circumcision status: uncircumcised men were 4 times more likely to be HIV-positive than circumcised men. Other studies conducted in the region indicate that circumcised status may be overreported by as much as 10%,12 which leaves the possibility open that our results underestimate the effect of circumcision to some degree. Our findings add to the large body of research indicating that circumcision has a protective effect against HIV infection among men. However, because circumcision is very closely correlated with ethnicity and culture, because not all studies find a protective effect of circumcision, and because there could be a confounding relationship between circumcision and ulcerative STIs such as HSV-2, well-controlled evidence from other national and disciplinary contexts should be considered before widespread planning and implementation of circumcision-focused interventions.
Alcohol consumption proved to have a significant relationship to HIV serostatus for both women and men. For women, any reported consumption of alcohol increases risk; it may be that the consumption of alcohol by a Kenyan woman serves as a broader indicator of lifestyle because it is not common practice for Kenyan women to consume alcoholic beverages. Only men who report having consumed alcohol fairly frequently in the past month are significantly more likely to be HIV-positive.
Sex-related behavioral factors did not have as great an impact in the analyses as expected, although other studies have also failed to find the expected relationships between sexual behavior and HIV serostatus (eg, Lagarde et al24 and Morison et al25). The failure to find the expected relationships may be explained in part by data quality issues (respondents may not report their actual number of recent sexual partners) or imprecision of the variable used in the analysis (ever-exchange of sex for money or goods is a vague indicator of behavioral risk). However, it also must be acknowledged that "risky" sexual behavior while increasing individual risk for contracting HIV may not in fact be the primary driving force behind the epidemic in Kenya. Other factors, such as those that enhance the biological transmission of HIV, may simply matter more.
This analysis demonstrates that HIV is a multidimensional epidemic, with demographic, residential, social, biological, and behavioral factors exerting influence on individual probability of becoming infected with HIV. Although all of these factors contribute to the risk profile for a given individual, ultimately, the results suggest that differences in biological factors may be more important in assessing risk for HIV than differences in sexual behavior. The ways in which these intersecting factors affect risk differ by sex, which implies that program interventions may require gender-specific approaches. Above all, the findings reiterate that the situation of Nyanza Province is egregious within Kenya and is clearly in need of a broad-spectrum approach to HIV prevention, testing and counseling, and treatment.
The authors gratefully acknowledge Jeffrey Mewbourn's assistance with library services. This research was funded in part by USAID under its MEASURE DHS project.
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*For details on response rate calculation, on the collection of dried blood spots for HIV testing and on ethical protocols, refer to, respectively, Appendix A, Chapter 13, and Chapter 1.10 in the 2003 Kenya DHS Final Report.3 Cited Here...
†An investigation into the effect of nonresponse on the representativeness of the Kenya DHS HIV data has been undertaken and is available from the authors. In short, it was found that nonresponse to the survey did not significantly bias the prevalence estimates. Cited Here...
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Current Opinion in Infectious DiseasesCircumcision and HIV transmissionCurrent Opinion in Infectious Diseases
Keywords:© 2006 Lippincott Williams & Wilkins, Inc.
Kenya; HIV/AIDS; seroprevalence; circumcision