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Behaviour
Original article
Discordance of HIV and HSV-2 biomarkers and self-reported sexual behaviour among orphan adolescents in Western Kenya
  1. Hyunsan Cho1,
  2. Winnie Luseno1,
  3. Carolyn Halpern2,
  4. Lei Zhang1,
  5. Isabella Mbai3,
  6. Benson Milimo3,
  7. Denise Dion Hallfors1
  1. 1The Pacific Institute for Research and Evaluation, Chapel Hill, North Carolina, USA
  2. 2Department of Maternal and Child Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  3. 3School of Nursing, Moi University, Eldoret, Kenya
  1. Correspondence to Dr Hyunsan Cho, The Pacific Institute for Research and Evaluation, 1516 E. Franklin St., Suite 200, Chapel Hill, NC 27514, USA; cho{at}pire.org

Abstract

Background This paper examines the discordance between biological data of HIV and herpes simplex virus type 2 (HSV-2) infections and self-reported questionnaire responses among orphan adolescents in Western Kenya.

Methods In 2011, 837 orphan adolescents from 26 primary schools were enrolled in an HIV prevention trial. At baseline, blood samples were drawn for HIV and HSV-2 infection biomarker testing, and participants completed an audio computer-assisted self-interviewing survey.

Results Comparing biological data with self-reported responses indicated that 70% of HIV-positive (7 out of 10) and 64% of HSV-2-positive (18 out of 28 positive) participants reported never having had sex. Among ever-married adolescents, 65% (57 out of 88) reported never having had sex. Overall, 10% of study participants appeared to have inconsistently reported their sexual behaviour. Logistic regression analyses indicated that lower educational level and exam scores were significant predictors of inconsistent reporting.

Conclusions Our study demonstrates the discordance between infections measured by biomarkers and self-reports of having had sex among orphan adolescents in Kenya. In order to detect programme effects accurately in prevention research, it is necessary to collect both baseline and endline biological data. Furthermore, it is recommended to triangulate multiple data sources about adolescent participants’ self-reported information about marriage and pregnancies from school records and parent/guardians to verify the information. Researchers should recognise potential threats to validity in data and design surveys to consider cognitive factors and/or cultural context to obtain more accurate and reliable information from adolescents regarding HIV/sexually transmitted infection risk behaviours.

Clinical Trail Registration number: NCT01501864.

  • HIV
  • HSV
  • SEXUAL BEHAVIOUR
  • ADOLESCENT
  • AFRICA

https://doi.org/10.1136/sextrans-2014-051720

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    Introduction

    Globally, over two-thirds of persons aged 15–49 years who are infected with HIV reside in sub-Saharan Africa (SSA).1 Youth aged 15–24 years account for an estimated 40% of new infections among adults, with 79% of new infections occurring among youth in SSA.2 The HIV/AIDS pandemic has resulted in millions of orphans in that region. Prevention remains critically important for youth, especially orphan adolescents who are exceptionally vulnerable to HIV risk behaviours compared with non-orphan youth.3

    Most HIV prevention research has relied on self-reports of sexual behaviours4 despite the fact that they are subject to bias in regard to recall, poor comprehension of questionnaire items5 or social desirability and/or cultural norms regarding socially acceptable behaviour.6 Thus, there has been an increasing call for biological markers as objective outcomes in evaluating the effectiveness of interventions to reduce the incidence of HIV and other sexually transmitted infections (STIs).7 ,8

    Herpes simplex virus type 2 (HSV-2) is one of the most prevalent STIs worldwide and is associated with HIV infection.9 Researchers have used HSV-2 as a proxy indicator for sexual behaviour in prevention research.8 ,10 Although biomarker data are believed to be more valid than self-reported data, one cannot assume that an infected adolescent acquired HIV through sexual transmission as mother-to-child transmission (MTCT) accounts for a significant proportion of adolescent HIV infections in SSA.11 Furthermore, absence of HSV-2 infection does not necessarily suggest sexual inexperience.12 Because large sample sizes are required to demonstrate prevention of low-prevalence infections, biomarker data collection may not always be practical and cost effective for prevention research.13

    Problems of consistency in self-reported sexual behaviour, particularly for adolescents, are well known.14 ,15 Researchers have estimated the extent of the problem by checking the inconsistency within self-reported survey items and/or across time points using repeated measurements.16–18 For example, the majority (95%–100%) of 11-year-old to 14-year-old adolescents in Jamaica responded consistently about first sexual intercourse within each given survey round. However, across three waves of surveys, 37% of respondents—12% of girls and 65% of boys—responded inconsistently about the timing of their sexual debut.17 In a Kenyan study of adolescents aged 12–19 years (49% of whom were sexually active), 20% gave inconsistent reports about lifetime sexual intercourse and timing of first sexual intercourse,16 and in South Africa, 40% of sexually active adolescents inconsistently reported lifetime sexual experience.18

    Another approach is to examine inconsistency across different types of data, for example, comparing biomarker measures with self-reported survey or face-to-face interviews.10 ,14 ,19 ,20 One study found that only 52% of adults with biomarkers indicating recent semen exposure reported unprotected sex during the previous 2 days among Zimbabwean women.20 In another study in Zimbabwe, four girls who were pregnant did not report having had sexual intercourse.10 Other research found that 58% of male and 29% of female Tanzanian adolescents positive for HIV infection, pregnancy or STIs reported ever having sex in both audio computer-assisted self-interviewing (ACASI) and face-to-face interviews.15

    Researchers have focused on whether socio-demographic factors influence inconsistent self-reports of sexual behaviours. Although patterns vary across studies, findings suggest that boys,5 ,16 ,17 persons of lower socioeconomic status (SES) and those who live in slums16 ,17 are more likely to report inconsistently. However, patterns related to an association between education and inconsistent reporting are mixed. Beguy et al16 found that youth in school are more likely to misreport their sexual experience than youth not in school and that attaining secondary school education compared with primary school is not a significant predictor of inconsistent reporting in Kenya. Findings on an association between age and inconsistent self-reports have also been conflicting. Older adolescents were more likely to inconsistently report sexual activity but less likely to retract previous claims of sexual activity.5 ,16

    Accurate and comprehensive data are necessary to estimate HIV prevalence and identify risky sexual behaviours among vulnerable adolescents to develop effective prevention strategies. However, relatively little attention has been paid to the link between cognitive factors and reliability of data among orphans in developing countries. The purpose of this study is to examine the consistency of reporting of sexual behaviours within survey items and to compare them with biomarkers of HIV and HSV-2 infections from an HIV prevention trial. We also examine the association of socio-demographic and cognitive factors with inconsistent reporting among orphan adolescents in Kenya.

    Materials and methods

    Study area

    This study uses baseline data collected in an ongoing randomised controlled trial (RCT) in Kenya testing whether providing school support will reduce risky sexual behaviours and prevent HIV/HSV-2 infection among orphan adolescents. The trial was conducted in Siaya District in Nyanza Province. Nyanza has the highest HIV prevalence and orphanhood in Kenya.21 Almost all of the participants are of Luo ethnicity; Luos have the highest HIV prevalence among Kenyan ethnic groups.22

    Sample

    We selected 26 primary schools with at least 20 orphans per school in 2011. An orphan was defined as an adolescent who had lost one or both parents to death from any cause. We invited all orphans in grades 7 and 8 in 26 primary schools to participate in the study (n=934) and 837 completed both student survey and biomarker testing (see figure 1). All participation was voluntary. We obtained written informed permission from either a surviving parent or custodial guardian and written assent from all participants for study participation. The institutional review boards of PIRE (US) and Moi University (Kenya) reviewed and approved all study procedures.

    Figure 1
    Figure 1

    Study design flowchart.

    Measures

    Biomarkers data included HIV and HSV-2 infection (positive or not). Detailed description of our biomarker data collection procedures is provided elsewhere.23 We conducted the baseline survey using ACASI on personal digital assistant (PDA) devices. The self-administered questionnaire was originally developed from several validated instruments and has been used in a previous pilot study in Kenya24 as well as a similar Zimbabwean study.25 We added several items from the Kenya Demographic and Health Survey (KDHS).22 The final survey was translated into the Luo language and back-translated. Participants could read and respond to questions in either Luo or English. Sexual debut was measured by the survey item, ‘Have you ever had sexual intercourse?’ Marriage was measured by the survey item never married versus either currently/ever married or living with a man/woman as if married. Pregnancy was measured by combining the following survey items: ‘Are you pregnant?’; ‘Have you ever had a pregnancy that miscarried, was aborted or ended in a stillbirth?’; ‘Have you ever given birth?’; and, for boys, ‘Have you ever fathered any children with any woman?’ (all coded yes or no). The survey also included orphan type (double, maternal or paternal), age and an SES count index (α=0.62, 13 items). For cognitive development, we included grade level and the Kenya Certificate of Primary Education (KCPE) score, coded in four categories: >300, 201–300, ≤200 and no score. The KCPE is a national standardised exam with a maximum score of 500, taken in the eighth year of primary school. Results are used by high schools to select capable students. Test scores for grade 7 students were collected after they took the exam in grade 8. Students may be without scores because of repeating a grade, not meeting eligibility criteria for taking the test or inability to pay the examination fee.

    Inconsistency

    We compared answers across survey items within the same questionnaire and compared self-reported and biomarker data. We constructed four inconsistent groups: (1) ‘married/pregnant but no sex’ (ie, participant reported never having sex but was married/pregnant); (2) ‘HSV-2-positive but no sex’ (reported never having sex but was HSV-2-positive) and (3) ‘HIV-positive but no sex’ (reported never having sex but was HIV-positive). The fourth group, ‘combined inconsistent group’, contained all study participants belonging to inconsistent groups 1–3.

    Analysis

    First, we conducted descriptive analyses regarding sample characteristics. Second, we used bivariate analyses to describe demographic characteristics related to HIV/HSV-2 infection and sexual behaviours. Third, we examined inconsistencies within survey items (eg, married status against sexual debut) and between biological markers of HIV/HSV-2 infection and survey items. We conducted survey logistic regression analyses in SAS (SAS V.9.3) to examine factors associated with inconsistent reports, taking into account the design effects that students are nested within schools. The four groupings of inconsistent reporting were used as dependent variables. We included grade level, gender, orphan type, SES and KCPE score as predictors.

    Results

    Participant baseline characteristics

    Table 1 shows the characteristics of study participants. About half of participants were women, and the mean age was 15 years. Sixty-one per cent of participants were in grade 7. In both grades 7 and 8, almost half (47%) were two or more years older than the expected age for grade (ie, 13 years in grade 7 and 14 years in grade 8). About half were double or maternal orphans rather than paternal. On average, participants reported that their household owned five assets and/or amenities (eg, farm animal, bicycle). The average KCPE score was 260 (range=101–398). Twenty-eight percent of participants had low scores of <200, 48% had scores in the medium range between 201 and 300, 15% had high scores that were >300 and 9% had missing scores.

    View this table:
    Table 1

    Demographic characteristics of study sample (total sample N=837)

    Table 2 presents prevalence of HIV/HSV-2 infection and sexual behaviours as well as their bivariate associations with demographic variables. At baseline, 10 male and 18 female participants were HSV-2-positive (prevalence=3.2%); five female and five male participants were HIV-positive (prevalence=1.2%). HSV-2 and HIV infections were not significantly associated with any demographic variables. Overall, 185 participants (22%) reported ever having sex. Male participants and adolescents aged 18 years old or older were more likely to have had sex. Double or maternal orphans had a higher proportion reporting sexual experience compared with paternal. A total of 88 (10.5%) students reported being currently or ever married and 6 (0.7%) girls reported they were currently or ever pregnant. Students in grade 7 were more likely to be married/pregnant compared with grade 8. SES was not associated with any study outcome.

    View this table:
    Table 2

    Demographic characteristics of HIV/HSV-2 infection and risky sexual behaviours

    Predictors of inconsistent reporting

    As shown in table 3, about 7% of participants were in the category ‘married/pregnant but no sex’, 2.2% were in the group ‘HSV-2-positive but no sex’ and 0.8% in the ‘HIV-positive but no sex’ group. In total, 70% of HIV-positive (7 out of 10) and 64% of HSV-2-positive (18 out of 28 positive) participants reported never having had sex. Among ever-married adolescents, 65% (57 out of 88) reported never having had sex. These groups are mutually exclusive except for one case. Of the total sample, 10% were in the ‘combined inconsistent group’. Grade and KCPE score were significant predictors of ‘married/pregnant but no sex’. Participants in grade 7 had 5.91 higher odds of inconsistent reporting than those in grade 8 (p=0.00). Participants with KCPE scores higher than 200 (OR=0.27) and 300 (OR=0.12) were less likely than those with scores <200 to be in this group (p=0.01). For the ‘HSV-2-positive but no sex’ and ‘HIV-positive but no sex’ groups, none of the predictors were significant. For the ‘combined inconsistent group’, we found that participants in grade 7 had 2.37 higher odds of inconsistent reporting than grade 8 (p=0.01) and those with KCPE scores above 300 had a lower likelihood of inconsistent reporting (OR=0.24, p=0.03) than those scoring <200.

    View this table:
    Table 3

    Predictors of inconsistent group: survey logistic regression

    Discussion

    We reported the baseline prevalence of sexual experience and HIV/HSV-2 from an ongoing RCT to examine discordance between biological data and self-reported questionnaire responses among orphan adolescents in Kenya. Overall, 10% of the sample exhibited inconsistency either within their responses to survey items or between the survey and biological data. In total, 75% of the HIV-positive participants, 64% of HSV-2-positive and 65% of married orphans reported never having had sex. Cognitive development measures (grade level and academic performance) were significant predictors of inconsistent reporting. Proportions of inconsistent reporting in our study are comparable with previous studies. Using a random sample of persons aged 13–34 years in Kenya's Nyanza province, Amornkul et al26 found that among women who denied ever having had sexual intercourse, 1.3% were HIV-positive and 1.6% were pregnant, while 0.8% of men who denied ever having had sex were HIV-positive. Another study found that among Tanzanian adolescents testing positive for HIV, 50% of the men and no women reported sexual debut in both questionnaire and face-to-face interview.14

    Although we treat the ‘HIV-positive but no sex’ as an inconsistent group, it is possible that some orphans were infected perinatally and survived to adolescence. The equal number of female and male participants infected in our sample in a high HIV prevalence area might reflect perinatal infection because sexually acquired HIV infection tends to be higher among female than male participants.27 Given the high sensitivity and specificity of HIV testing methods used in this study,23 we can assume that all participants who were negative at baseline but are newly HIV-positive at the endpoint will have acquired HIV infection through unprotected sexual contact during the study. Unfortunately, all three previous RCTs testing the effect of school support on HIV risk conducted in SSA collected only endpoint biomarkers and not baseline.7 ,25 ,28

    Because the sensitivity and specificity of Kalon is not 100%,12 some of those in the HSV-2-positive group could have correctly reported not having had sex. We also cannot assume that those who were HSV-2-negative and had reported never having had sex were consistent reporters. However, the bias should be equal regardless of study condition, and the baseline data will help us examine whether baseline HSV-2-positives still test as positive at endpoint and also whether new infection rates will differ by condition.

    Consistent with previous research, our cognitive development measures were significant predictors of inconsistent reporting. Upchurch et al5 found that US adolescents with lower vocabulary test scores were more likely than those scoring higher to provide inconsistent or rescinded reports of sexual intercourse. Another study reported that Zimbabwe women with lower education (primary school or less) reported more problems using ACASI, the keyboard and correcting mistakes than women in higher educational groups.29 Our participants in grade 8 and those with higher exam scores compared with their counterparts may have been better able to comprehend survey questions and therefore provide accurate answers, and have less trouble using the PDA during the survey. However, Beguy et al16 found secondary school attainment among Kenyan adolescents unrelated to consistent reporting of sexual experience over time, and, among inconsistent reporters, better educated adolescents with higher literacy levels were more likely to retract their initial claim of sexual experience and provide valid answers regarding timing of sex. Palen et al18 also found that ever failing a grade in school was unrelated to inconsistent reporting of sexual experience among South African adolescents.

    We found that 10.5% of participants reported being currently or ever married, and, among them, 65% reported never having had sex. The KDHS indicates that 12% of women aged 15–19 were either married or living together compared with 0.4% of same-age men.22 The marriage rate of our female participants is consistent with the KDHS report while it was much higher among our study's male orphans. It should be noted that Kenyan school policy does not prohibit married or pregnant youth from attending school. Further data corroborating self-reported marital status may be helpful to rule out reporting errors.30 We currently collect data regarding school dropout and the reasons for dropout from school personnel, but they may not be aware of the marital status of a child who is attending school.

    We found that 22% of participants with an average age of 15 were sexually active. This is comparable with KDHS findings that 18% of women aged 15–24 years and 27% of men aged 15–24 years had reported sexual intercourse before the age of 15 years in Nyanza Province.22 However, Amornkul et al26 reported 43.9% of women and 50.2% of men aged 13–19 years having ever had sexual intercourse in the study area. It is possible that students are less willing to disclose their sexual activity in a school survey if schools have health programmes endorsing abstinence.16 It is also possible that our participants did not report sexual debut if they had been forced to have sex,18 had sex other than penile-vaginal sexual intercourse or conceptualised sexual intercourse differently. However, we followed our Kenyan research staff's recommendation to not attempt to further define ‘sexual intercourse’ or ask about other sexual activity (eg, oral sex) because these would be inappropriate questions culturally.

    Our findings may not be generalisable to Kenyan adolescents as a whole because this study is of Luo orphaned adolescents in a high HIV prevalence area in rural Western Kenya. To our knowledge, this is the first orphan study examining inconsistency using both biomarker and survey data. Compared with previous studies that examined several rounds of a survey to assess inconsistency, we examined the discordance between biomarker with survey responses within a single assessment. Causal factors for inconsistent reporting within a single assessment may be different from those identified in several rounds of survey administrations. However, using the baseline data before the intervention started could help to minimise the bias of students reporting desirable or socially acceptable answers for researchers, especially among participants in the intervention arm in an RCT.

    In summary, our study demonstrates the discordance between biological data with self-reports of sexual behaviour in HIV prevention research. Although biological data are regarded as a more valid measure compared with self-reports of sexual behaviour, potential limitations must also be considered. In order to measure true programme effects, it is essential to collect both baseline and endpoint biological data in HIV prevention trials because it allows us to more accurately determine programme effects and rule out alternative explanations such as MTCT. We conclude that adolescents who are more challenged in academic competency are less consistent reporters, but we found no differences by gender or age. Given these findings, researchers should consider how to develop questionnaires based on the educational and cognitive development of the target population. It is also critical for programme evaluators to take into account whether specific groups have a tendency to misreport when evaluating programme effects. Finally, triangulating multiple data sources about participants as reported by school records and parent/guardian is important in verifying self-reported information about marriage and pregnancies and is highly recommended.

    Key messages

    • Almost half of orphans in grades 7 and 8 were two or more years older than the appropriate age for grade.

    • In total, 70% of HIV-positive participants and 64% of HSV-2-positive participants reported that they had never had sexual intercourse.

    • Lower grade level and poor academic performance were significant predictors of inconsistent reporting among orphan adolescents.

    References

    1. ↵
      The Joint United Nations Programme on HIV/AIDS (UNAIDS). Regional Fact Sheet 2012. Sub-Saharan Africa. Geneva: UNAIDS, 2012.
    2. ↵
      The United Nations Children's Fund (UNICEF). Opportunity in Crisis: preventing HIV from early adolescence to young adulthood. New York: UNICEF, 2011.
    3. ↵
      1. Operario D,
      2. Underhill K,
      3. Chuong C, et al
      . HIV Infection and sexual risk behaviour among youth who have experienced orphanhood: systematic review and meta analysis. JIAS 2011;14:25.
      OpenUrlCrossRef
    4. ↵
      1. Cowan F,
      2. Pettifor A
      . HIV in adolescents in sub-Saharan Africa. Curr Opin HIV AIDS 2009;4:288–93.
      OpenUrlCrossRefPubMedWeb of Science
    5. ↵
      1. Upchurch DM,
      2. Lillard LA,
      3. Aneshensel CS, et al
      . Inconsistencies in reporting the occurrence and timing of first intercourse among adolescents. J Sex Res 2002;39:197–206.
      OpenUrlCrossRefPubMedWeb of Science
    6. ↵
      1. Alexander CS,
      2. Somerfield MR,
      3. Ensminger ME, et al
      . Consistency of adolescents’ self-reports of sexual behavior in a longitudinal study. J Youth Adolesc 1993;22:455–71.
      OpenUrlCrossRefWeb of Science
    7. ↵
      1. Baird SJ,
      2. Garfein RS,
      3. McIntosh CT, et al
      . Effect of a cash transfer programme for schooling on prevalence of HIV and herpes simplex type 2 in Malawi: a cluster randomised trial. Lancet 2012;379:1320–9.
      OpenUrlCrossRefPubMedWeb of Science
    8. ↵
      1. Ross DA,
      2. Changalucha J,
      3. Obasi AI, et al
      . Biological and behavioural impact of an adolescent sexual health intervention in Tanzania: a community-randomized trial. AIDS 2007;21:1943–55.
      OpenUrlCrossRefPubMedWeb of Science
    9. ↵
      1. Abu-Raddad LJ,
      2. Magaret AS,
      3. Celum C, et al
      . Genital herpes has played a more important role than any other sexually transmitted infection in driving HIV prevalence in Africa. PLoS One 2008;3:e2230.
      OpenUrlCrossRefPubMed
    10. ↵
      1. Cowan FM,
      2. Pascoe SJS,
      3. Langhaug LF, et al
      . The Regai Dzive Shiri Project: a cluster randomised controlled trial to determine the effectiveness of a multi-component community-based HIV prevention intervention for rural youth in Zimbabwe—study design and baseline results. Trop Med Int Health 2008;13:1235–44.
      OpenUrlCrossRefPubMedWeb of Science
    11. ↵
      1. Ferrand RA,
      2. Corbett EL,
      3. Wood R, et al
      . AIDS among older children and adolescents in Southern Africa: projecting the time course and magnitude of the epidemic. AIDS 2009;23:2039–46.
      OpenUrlCrossRefPubMedWeb of Science
    12. ↵
      1. Bastien S,
      2. Mason-Jones AJ,
      3. De Koker P, et al
      . Herpes simplex virus type 2 infection as a biomarker for sexual debut among young people in sub-Saharan Africa: a literature review. Int J STD AIDS 2012;23:761–6.
      OpenUrlAbstract/FREE Full Text
    13. ↵
      1. Fishbein M,
      2. Pequegnat W
      . Evaluating AIDS prevention interventions using behavioral and biological outcome measures. Sex Transm Dis 2000;27:101–10.
      OpenUrlCrossRefPubMedWeb of Science
    14. ↵
      1. Plummer ML,
      2. Ross DA,
      3. Wight D, et al
      . “A bit more truthful”: the validity of adolescent sexual behavior data collected in rural northern Tanzania using five methods. Sexual Transm Infect 2004;80(Suppl II):49–56.
      OpenUrl
    15. ↵
      1. Plummer ML,
      2. Wight D,
      3. Ross DA, et al
      . Asking semi-literate adolescents about sexual behaviour: the validity of assisted self-completion questionnaire (ASCQ) data in rural Tanzania. Trop Med Int Health 2004;9:737–54.
      OpenUrlCrossRefPubMedWeb of Science
    16. ↵
      1. Beguy D,
      2. Kabiru CW,
      3. Nderu EN, et al
      . Inconsistencies in self-reporting of sexual activity among young people in Nairobi, Kenya. J Adolesc Health 2009;45:595–601.
      OpenUrlCrossRefPubMedWeb of Science
    17. ↵
      1. Eggleston E,
      2. Leitch J,
      3. Jackson J
      . Consistency of self-reports of sexual activity among young adolescents in Jamaica. Int Fam Plan Perspect 2000;29:79–83.
      OpenUrl
    18. ↵
      1. Palen L,
      2. Smith E,
      3. Caldwell L, et al
      . Inconsistent reports of sexual intercourse among South African high school students. J Adolesc Health 2008;42:221–7.
      OpenUrlCrossRefPubMedWeb of Science
    19. ↵
      1. Hewett PC,
      2. Mensch BS,
      3. Erulkar AS
      . Consistency in the reporting of sexual behaviour by adolescent girls in Kenya: a comparison of interviewing methods. Sexual Transm Infect 2004;80(Suppl II):ii43–8.
      OpenUrlCrossRef
    20. ↵
      1. Minnis AM,
      2. Steiner M,
      3. Gallo MF, et al
      . Biomarker validation of reports of recent sexual activity: results of a randomized controlled study in Zimbabwe. Am J Epidemiol 2009;170:918–24.
      OpenUrlAbstract/FREE Full Text
    21. ↵
      National AIDS & STI Control Programme (NASCOP), Republic of Kenya. National Guidelines for HIV Testing and Counseling in Kenya. Nairobi, Kenya: NASCOP, 2008.
    22. ↵
      Kenya National Bureau of Statistics (KNBS) and ICF Macro. Kenya Demographic and Health Survey 2008–2009. Calverton, Maryland: KNBS and ICF Macro, 2010.
    23. ↵
      1. Luseno WK,
      2. Hallfors DD,
      3. Cho H, et al
      . Use of HIV and HSV-2 biomarkers in Sub-Saharan adolescent prevention research: a comparison of two approaches. J Prim Prev 2014;35:181–91.
      OpenUrlCrossRefPubMed
    24. ↵
      1. Cho H,
      2. Hallfors DD,
      3. Mbai II, et al
      . Keeping adolescent orphans in school as HIV prevention: evidence from a randomized controlled trial in Kenya. J Adolesc Health 2011;48:523–6.
      OpenUrlCrossRefPubMedWeb of Science
    25. ↵
      1. Hallfors D,
      2. Cho H,
      3. Rusakaniko S, et al
      . Supporting adolescent orphan girls to stay in school as HIV risk prevention: evidence from a randomized controlled trial in Zimbabwe. Am J Public Health 2011;101:1082–8.
      OpenUrlCrossRefPubMedWeb of Science
    26. ↵
      1. Amornkul PN,
      2. Vandenhoudt H,
      3. Nasokho P, et al
      . HIV prevalence and associated risk factors among individuals aged 13–34 years in Rural Western Kenya. Plos One 2009;4:e6470.
      OpenUrlCrossRefPubMed
    27. ↵
      1. Glynn JR,
      2. Caraël M,
      3. Auvert B, et al
      . Why do young women have a much higher prevalence of HIV than young men? A study in Kisumu, Kenya and Ndola, Zambia. AIDS 2001;15(Suppl 4):S51–60.
      OpenUrlCrossRefPubMedWeb of Science
    28. ↵
      1. Duflo E,
      2. Dupas P,
      3. Kremer M
      . Education, HIV, and early fertility: experimental evidence from Kenya. Unpublished manuscript available online 2012. http://www.povertyactionlab.org/publication/education-hiv-and-early-fertility-experimental-evidence-kenya (accessed 4 Jun 2014).
    29. ↵
      1. van de Wijgert J,
      2. Padian N,
      3. Shiboski S, et al
      . Is audio computer-assisted self-interviewing a feasible method of surveying in Zimbabwe? Int J Epidemiol 2000;29:885–90.
      OpenUrlAbstract/FREE Full Text
    30. ↵
      1. Langhang LF,
      2. Sherr L,
      3. Cowan FM
      . How to improve the validity of sexual behavior reporting: systematic review of questionnaire delivery modes in developing countries. Trop Med Int Health 2010;15:362–81.
      OpenUrlCrossRefPubMed

    Footnotes

    • Handling editor Jackie A Cassell

    • Contributors HC led the overall project concept and the writing of the paper. WL participated in the development of the paper, reviewed and summarised relevant literature, and provided critical reviews of each draft. CH guided the development of the paper and provided critical reviews and revisions on each draft. LZ conducted the data analyses and drafted the ‘Methods’ section. IM and BM oversaw data collection and human subjects protection in Kenya and reviewed and provided comments on manuscript drafts. DDH participated in the development of the paper, reviewed and summarised relevant literature, developed key points for the ‘Discussion’ section and critically reviewed multiple drafts.

    • Funding Research reported in this publication was supported by the National Institute of Mental Health of the National Institutes of Health under Award Number R01MH092215 (HC, PI).

    • Competing interests None.

    • Ethics approval Pacific Institute's PIRE IRB #3 and Institutional Research and Ethics Committee (IREC), Moi University.

    • Provenance and peer review Not commissioned; externally peer reviewed.