Bosny Pierre-Louis

University of North Carolina at Chapel Hill, North Carolina, United States

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Publications (9)23.66 Total impact

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    ABSTRACT: The past decade has seen an explosion in the availability and use of biomarkers data as a result of innovative discoveries and recent development of new biological and molecular techniques. Biomarkers are essential for at least four key purposes in biomedical research and public health practice: they are used for disease detection, diagnosis, prognosis, to identify patients who are most likely to benefit from selected therapies, and to guide clinical decision making. Determining the predictive and diagnostic value of biomarkers, singly and in combination, is essential to their being used effectively, and this has spurred the development of new statistical methodologies to assess the relationship between biomarkers and clinical outcomes. In this paper, we review both standard and novel statistical methods used for biomarker selection. We focus on techniques that could be readily applied to HIV infection research. Particular attention is given to deriving variable importance measures based on doubly robust methods such as targeted maximum likelihood estimation. We conclude by providing an example of the application of three novel techniques to a dataset from the Hormonal Contraception and HIV Genital Shedding and Disease Progression Study (GS Study) to select, among many candidate biomarkers, the best subset that is significantly associated with a CD4 cell decline to less than 350 cells/mm 3.
    No preview · Chapter · Dec 2012
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    ABSTRACT: Trichomoniasis vaginalis is the most common nonviral sexually transmitted infection (STI) worldwide, with a particularly high prevalence in regions of human immunodeficiency virus (HIV) endemicity. However, its impact as a cofactor for HIV acquisition is poorly understood. Samples from 213 women who experienced HIV seroconversion (cases) during a longitudinal study involving 4450 women in Uganda and Zimbabwe were matched with samples from HIV-uninfected women (controls). All samples underwent polymerase chain reaction (PCR) analysis for Trichomonas vaginalis DNA. For cases, analyzed samples were from the visit in which HIV seroconversion was detected and the visit preceding detection of seroconversion; for controls, one analyzed sample was from the visit matched by follow-up duration to the cases' seroconversion visit, and the other sample was from the visit immediately preceding the matched visit. The prevalence of T. vaginalis infection before HIV infection was 11.3% in cases and 4.5% in controls (P = .002). In multivariable analysis controlling for hormonal contraception, other STIs, behavioral, and demographic factors, the adjusted odds ratio for HIV acquisition was 2.74 (95% confidence interval, 1.25-6.00) for T. vaginalis-positive cases. The presence of behavioral risk factors for HIV infection, study recruitment from a referral population at high-risk for HIV, primary sex partner-associated risk for HIV infection, and herpes simplex virus type 2 seropositivity were also predictive of incident HIV infection. T. vaginalis infection is strongly associated with an increased risk for HIV infection in this general population of African women. Given the high prevalence of T. vaginalis infection in HIV-endemic areas, T. vaginalis control may have a substantial impact on preventing HIV acquisition among women.
    No preview · Article · Mar 2008 · The Journal of Infectious Diseases
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    ABSTRACT: Although the IUD is an extremely effective and low-cost contraceptive method, its use has declined sharply in Kenya in the past 20 years. A study tested the effectiveness of an outreach intervention to family planning providers and community-based distribution (CBD) agents in promoting use of the IUD in western Kenya. Forty-five public health clinics were randomized to receive the intervention for providers only, for CBD agents only, for both providers and CBD agents, or no detailing at all. The intervention is based on pharmaceutical companies' "detailing" models and included education/motivation visits to providers and CBD programmes, as well as provision of educational and promotional materials. District health supervisors were given updates on contraceptives, including the IUD, and were trained in communication and message development prior to making their detailing visits. Detailing only modestly increased the provision of IUDs, and only when both providers and CBD agents were targeted. The two detailing visits do not appear sufficient to sustain the effect of the intervention or to address poor provider attitudes and lack of technical skills. The cost per 3.5 years of pregnancy protection was US$49.57 for the detailing intervention including the cost of the IUD, compared with US$15.19 for the commodity costs of the current standard of care--provision of the injectable contraceptive depot-medroxyprogesterone acetate (DMPA). The effectiveness of provider-based activities is amplified when concurrent demand creation activities are carried out. However, the cost of the detailing in comparison to the small number of IUDs inserted indicates that this intervention is not cost-effective.
    No preview · Article · Feb 2008 · Journal of Biosocial Science
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    ABSTRACT: Increased menstrual bleeding and pain are the primary side effects that lead to early removal of the copper intrauterine device (IUD). Ibuprofen and other non-steroidal anti-inflammatory drugs (NSAIDs) are proven treatments for such IUD-induced problems, but their effect on early IUD removal is unknown. A total of 2019 first-time IUD users were recruited in Chile for this double-blind, randomized, placebo-controlled trial. Half of the participants were given ibuprofen and instructions to take 1200 mg daily during menses (for up to 5 days each cycle) for the first 6 months of IUD use. The other half were asked to take an identical appearing placebo in the same manner. The primary outcome was IUD removal within 12 months of insertion. A total of 1011 and 1008 women were randomly assigned to ibuprofen and placebo, respectively. During 12 months of observation, 190 had the device removed because of dysmenorrhoea and/or increased menstrual bleeding: 85 in the placebo group and 105 in the ibuprofen group. For ibuprofen users, the hazard ratio for removal for these IUD-induced side effects was 1.0 and 1.2 at 6 and 12 months, respectively (both not significant). Although increased menstrual bleeding and pain are common reasons for early IUD removal, prophylactic use of ibuprofen, at the dosage used here, does not reduce removal rates.
    Full-text · Article · Jul 2006 · Human Reproduction
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    ABSTRACT: Many ministries of health worldwide would like to increase use of the intrauterine device (IUD) since it is very safe, effective and inexpensive to provide. Efforts to stimulate interest in the method have not been rigorously tested. A randomized trial was conducted among 40 clinics in Nicaragua to test the impact of medical education on both IUD uptake and on provider knowledge/attitude toward the method. Two types of interventions were used: face-to-face medical training/education of providers and/or provision of an IUD checklist to help clinicians assess the medical eligibility of clients. The interventions had no impact on uptake of the IUD or on provider knowledge/attitude. While medical education and job tools (such as a checklist) for providers are indispensable for ensuring quality care, they may not be adequate to stimulate interest in the IUD on the part of clients.
    No preview · Article · Jul 2006 · Contraception
  • D Hubacher · V Reyes · S Lillo · A Zepeda · B Pierre-Louis · H Croxatto

    No preview · Article · Sep 2005 · Contraception
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    ABSTRACT: Women with diabetes need safe, effective contraception. Although intrauterine devices provide superior contraception, concerns remain that progestin absorbed systemically from the levonorgestrel-releasing device may impair carbohydrate metabolism. To examine the effect of the levonorgestrel-releasing intrauterine system on glucose metabolism in diabetic women. We randomly assigned 62 women with uncomplicated insulin-dependent diabetes mellitus to either a levonorgestrel-releasing or a copper T 380A intrauterine device. The primary outcome to assess glucose metabolism was glycosylated hemoglobin; fasting serum-glucose levels and daily insulin dose requirements over 12 months of observation were examined as well. Outcome data were available for 29 women using the levonorgestrel-releasing and 30 using the copper device. At 12 months, mean glycosylated levels were similar for women of the 2 groups (6.3%, standard deviation [SD] +/- 1.5 compared with 6.3%, SD +/- 1.3, respectively). The same was true for mean fasting-serum glucose levels (7.4 mM, SD +/- 4.2 compared with 7.5 mM, SD +/- 4.2) and daily insulin doses (35.1 units, SD +/- 12.8 compared with 36.4 units, SD +/- 9.0). No important differences were noted at either 6 weeks or 6 months. The levonorgestrel-releasing device had no adverse effect on glucose metabolism, even at the 6-week observation when systemic levels of levonorgestrel would have been higher than at later observations. Concern about a potential adverse effect of this contraceptive on glucose control is unwarranted, and its use in women with diabetes should be liberalized. I.
    No preview · Article · May 2005 · Obstetrics and Gynecology
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    ABSTRACT: In most recent large efficacy trials of barrier contraceptive methods, a high proportion of participants withdrew before the intended end of follow-up. The objective of this analysis was to explore characteristics of participants who failed to complete seven months of planned participation in a trial of spermicide efficacy. Trial participants were expected to use the assigned spermicide for contraception for 7 months or until pregnancy occurred. In bivariable and multivariable analyses, we assessed the associations between failure to complete the trial and 17 pre-specified baseline characteristics. In addition, among women who participated for at least 6 weeks, we evaluated the relationships between failure to complete, various features of their first 6 weeks of experience with the spermicide, and characteristics of the study centers and population. Of the 1514 participants in this analysis, 635 (42%) failed to complete the study for reasons other than pregnancy. Women were significantly less likely to complete if they were younger or unmarried, had intercourse at least 8 times per month, or were enrolled at a university center or at a center that enrolled fewer than 4 participants per month. Noncompliance with study procedures in the first 6 weeks was also associated with subsequent early withdrawal, but dissatisfaction with the spermicide was not. However, many participants without these risk factors withdrew early. Failure to complete is a major problem in barrier method trials that seriously compromises the interpretation of results. Targeting retention efforts at women at high risk for early withdrawal is not likely to address the problem sufficiently.
    Full-text · Article · Nov 2004 · BMC Medical Research Methodology
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