An HIV-1 risk assessment tool for women aged 15-49 in African countries: A pooled analysis across 15 nationally representative surveys.

BACKGROUND: Women in Africa disproportionately acquire HIV-1. Understanding which women are most likely to acquire HIV-1 can guide focused prevention with pre-exposure prophylaxis (PrEP). Our objective is to identify women at highest risk of HIV-1 and estimate PrEP efficiency at different sensitivity levels. METHODS: Nationally representative data were collected from 2015-2019 from 15 population-based household surveys. This analysis included women aged 15-49 who tested HIV-1 sero-negative or had recent HIV-1. Least absolute shrinkage and selection operator regression models were fit with 28 variables to predict recent HIV-1. Models were trained on the full population and internally cross-validated. Performance was evaluated using area under the receiver-operating-characteristic curve (AUC), sensitivity, and number needed to treat (NNT) with PrEP to avert one infection. RESULTS: Among 209,012 participants 248 had recent HIV-1 infection, representing 118 million women and 402,000 (95% CI: 309,000-495,000) new annual infections. Two variables were retained in the model: living in a subnational area with high HIV-1 viremia and having a sexual partner living outside the home. Full-population AUC was 0.80 (95% CI: 0.76-0.84); cross-validated AUC was 0.79 (95% CI: 0.75-0.84). At a sensitivity of 33%, up to 130,000 cases could be averted if 7.9 million women were perfectly adherent to PrEP; NNT would be 61. At a sensitivity of 67%, up to 260,000 cases could be averted if 25.1 million women were perfectly adherent to PrEP; the NNT would be 96. CONCLUSIONS: This risk assessment tool was generalizable, predictive, and parsimonious with tradeoffs between reach and efficiency.

Effect of HPV self-collection kits on cervical cancer screening uptake among under-screened women from low-income US backgrounds (MBMT-3): a phase 3, open-label, randomised controlled trial.

BACKGROUND: Most cervical cancer in the USA occurs in under-screened women. The My Body, My Test-3 (MBMT-3) trial sought to assess the efficacy of mailed human papillomavirus (HPV) self-collection kits with appointment-scheduling assistance to increase uptake of cervical cancer screening among under-screened women from low-income backgrounds compared with scheduling assistance alone. METHODS: MBMT-3 is a phase 3, open-label, two-arm, randomised controlled trial. Participants were recruited from 22 counties in North Carolina state, USA, and we partnered with 21 clinics across these counties. Participants were eligible for inclusion if they were aged 25-64 years, had an intact cervix, were uninsured or enrolled in Medicaid or Medicare, had an income of 250% or less of the US Federal Poverty Level, were living within the catchment area of a trial-associated clinic, and were overdue for screening (ie, Papanicolaou test ≥4 years ago or high-risk HPV test ≥6 years ago). Participants were randomly assigned (2:1) to receive a mailed HPV self-collection kit and assistance for scheduling a free screening appointment (intervention group) or to receive scheduling assistance alone (control group). Randomisation was conducted by county using permuted blocks of nine patients and assignment to group was not masked. Participants in the intervention group were mailed HPV self-collection kits to collect a cervical-vaginal sample and return it by mail for testing. Samples were tested with the Aptima HPV assay (Hologic, San Diego, CA, USA), and participants were informed of high-risk HPV results by telephone call. Trial staff made up to three telephone call attempts to provide scheduling assistance for in-clinic screening for all participants. The primary outcome was cervical cancer screening uptake (ie, attending an in-clinic screening appointment or testing negative for high-risk HPV with a returned self-collected sample) within 6 months of enrolment in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02651883, and has been completed. FINDINGS: Recruitment occurred between April 11, 2016, and Dec 16, 2019. 4256 women contacted the trial to participate, of whom 899 (21%) were eligible for inclusion and 697 (78%) returned consent forms. Of those who consented, 461 (66%) women were randomly assigned to the intervention group and 236 (34%) women were randomly assigned to the control group. We excluded 32 ineligible women post-randomisation, leaving 665 for primary analysis. Screening uptake was higher in the intervention group (317 [72%] of 438) than control group (85 [37%] of 227; risk ratio 1·93, 95% CI 1·62-2·31). Among intervention participants, 341 (78%) of 438 returned a self-collection kit. Three participants reported hurt or injury when using the self-collection kit; no participants withdrew due to adverse effects. INTERPRETATION: Among under-screened women from low-income backgrounds, mailed HPV self-collection kits with scheduling assistance led to greater uptake of cervical cancer screening than scheduling assistance alone. At-home HPV self-collection testing has the potential to increase screening uptake among under-screened women. FUNDING: National Cancer Institute.

Cost-effectiveness of Human Papillomavirus Self-collection Intervention on Cervical Cancer Screening Uptake among Underscreened U.S. Persons with a Cervix.

BACKGROUND: We evaluate the cost-effectiveness of human papillomavirus (HPV) self-collection (followed by scheduling assistance for those who were HPV+ or inconclusive) compared with scheduling assistance only and usual care among underscreened persons with a cervix (PWAC). METHODS: A decision tree analysis was used to estimate the incremental cost-effectiveness ratios (ICER), or the cost per additional PWAC screened, from the Medicaid/state and clinic perspectives. A hypothetical cohort represented 90,807 low-income, underscreened individuals. Costs and health outcomes were derived from the MyBodyMyTest-3 randomized trial except the usual care health outcomes were derived from literature. We performed probabilistic sensitivity analyses (PSA) to evaluate model uncertainty. RESULTS: Screening uptake was highest in the self-collection alternative (n = 65,721), followed by the scheduling assistance alternative (n = 34,003) and usual care (n = 18,161). The self-collection alternative costs less and was more effective than the scheduling assistance alternative from the Medicaid/state perspective. Comparing the self-collection alternative with usual care, the ICERs were $284 per additional PWAC screened from the Medicaid/state perspective and $298 per additional PWAC screened from the clinic perspective. PSAs demonstrated that the self-collection alternative was cost-effective compared with usual care at a willingness-to-pay threshold of $300 per additional PWAC screened in 66% of simulations from the Medicaid/state perspective and 58% of simulations from the clinic perspective. CONCLUSIONS: Compared with usual care and scheduling assistance, mailing HPV self-collection kits to underscreened individuals appears to be cost-effective in increasing screening uptake. IMPACT: This is the first analysis to demonstrate the cost-effectiveness of mailed self-collection in the United States.

Day-of-Surgery Gabapentinoids and Prolonged Opioid Use: A Retrospective Cohort Study of Medicare Patients Using Electronic Health Records.

BACKGROUND: While preoperative gabapentinoids are commonly used in surgical multimodal analgesia protocols, little is known regarding the effects this therapy has on prolonged postsurgical opioid use. In this observational study, we used data from a large integrated health care system to estimate the association between preoperative day-of-surgery gabapentinoids and the risk of prolonged postsurgical opioid use. METHODS: We identified adults age ≥65 years undergoing major therapeutic surgical procedures from a large integrated health care system from 2016 to 2019. Exposure to preoperative gabapentinoids on the day of surgery was measured using inpatient medication administration records, and the outcome of prolonged opioid use was measured using outpatient medication orders. We used stabilized inverse probability of treatment-weighted log-binomial regression to estimate risk ratios and 95% confidence intervals (CIs) of prolonged opioid use, comparing patients who received preoperative gabapentinoids to those who did not and adjusting for relevant clinical factors. The main analysis was conducted in the overall surgical population, and a secondary analysis was conducted among procedures where at least 30% of all patients received a preoperative gabapentinoid. RESULTS: Overall, 13,958 surgical patients met inclusion criteria, of whom 21.0% received preoperative gabapentinoids. The observed 90-day risk of prolonged opioid use following surgery was 0.91% (95% CI, 0.77-1.08). Preoperative gabapentinoid administration was not associated with a reduced risk of prolonged opioid use in the main analysis conducted in a broad surgical population (adjusted risk ratio [adjRR], 1.19 [95% CI, 0.67-2.12]) or in the secondary analysis conducted in patients undergoing colorectal resection, hip arthroplasty, knee arthroplasty, or hysterectomy (adjRR, 1.01 [95% CI, 0.30-3.33]). CONCLUSIONS: In a large integrated health system, we did not find evidence that preoperative gabapentinoids were associated with reduced risk of prolonged opioid use in patients undergoing a broad range of surgeries.

Perceived Financial Barriers to Cervical Cancer Screening and Associated Cost Burden Among Low-Income, Under-Screened Women.

Background: Despite screening's effectiveness in reducing cervical cancer incidence and mortality, disparities in cervical cancer screening uptake remain, with lower rates documented among uninsured and low-income individuals. We examined perceived financial barriers to, and the perceived cost burden of, cervical cancer screening. Materials and Methods: We surveyed 702 low-income, uninsured or publicly insured women ages 25-64 years in North Carolina, U.S., who were not up to date on cervical cancer screening according to national guidelines. Participants were asked about perceived financial barriers to screening and how much they perceived screening would cost. We used multivariable logistic regression to assess the sociodemographic predictors of perceived financial barriers. Results: Seventy-two percent of participants perceived financial barriers to screening. Screening appointment costs (71%) and follow-up/future treatment costs (44%) were most commonly reported, followed by lost pay due to time missed from work (6%) and transportation costs (5%). In multivariable analysis, being uninsured (vs. publicly insured), younger (25-34 vs. 50-64 years), White (vs. Black), and not reporting income data were associated with perceiving screening costs and future treatment costs as barriers to screening. Participants reported wide-ranging estimates of the perceived out-of-pocket cost of screening ($0-$1300), with a median expected cost of $245. Conclusions: The majority of our sample of low-income women perceived substantial financial barriers to screening, particularly related to screening appointment costs and potential follow-up/future treatment costs. Providing greater cost transparency and access to financial assistance may reduce perceived financial barriers to screening, potentially increasing screening uptake among this underserved population. Clinicaltrials.gov registration number NCT02651883.

Modeling Adherence Interventions Among Youth with HIV in the United States: Clinical and Economic Projections.

The Adolescent Medicine Trials Network for HIV/AIDS Interventions is evaluating treatment adherence interventions (AI) to improve virologic suppression (VS) among youth with HIV (YWH). Using a microsimulation model, we compared two strategies: standard-of-care (SOC) and a hypothetical 12-month AI that increased cohort-level VS in YWH in care by an absolute ten percentage points and cost $100/month/person. Projected outcomes included primary HIV transmissions, deaths and life-expectancy, lifetime HIV-related costs, and incremental cost-effectiveness ratios (ICERs, $/quality-adjusted life-year [QALY]). Compared to SOC, AI would reduce HIV transmissions by 15% and deaths by 12% at 12 months. AI would improve discounted life expectancy/person by 8 months at an added lifetime cost/person of $5,300, resulting in an ICER of $7,900/QALY. AI would be cost-effective at $2,000/month/person or with efficacies as low as a 1 percentage point increase in VS. YWH-targeted adherence interventions with even modest efficacy could improve life expectancy, prevent onward HIV transmissions, and be cost-effective.

RESUMEN: La Red de Ensayos Médicos sobre Adolescentes para Realizar Intervenciones sobre el VIH/SIDA está evaluando intervenciones de adherencia (IAs) al tratamiento para mejorar la supresión virológica (SV) entre los jóvenes con VIH (JCV). Usando un modelo de microsimulación, comparamos dos estrategias: cuidado convencional (CC) y una intervención de adherencia hipotética durando 12 meses que aumentaría la SV a nivel de cohorte entre JCV en tratamiento por 10 puntos de porcentuales y que costaría US$ 100/mes/persona. Resultados proyectados incluyeron transmisiones de VIH primarias, muertes y esperanza de vida, costos de por vida asociados con el VIH, y razones incrementales de costo-efectividad (RICEs, $/año de vida ajustado por la calidad [AVAC]). Comparado al CC, la IA reduciría transmisiones de VIH por 15% y muertes por 12% a los 12 meses. La IA mejoraría esperanza de vida descontada/persona por 8 meses a un costo de por vida adicional/persona de US$ 5.300, resultando en una RICE de US$ 7.900/AVAC. La IA sería costo-efectiva a un costo de US$ 2.000/mes/persona o si mejorara SV por al menos un punto porcentual. Intervenciones de adherencia dirigidas a jóvenes con una eficacia incluso modesta podrían mejorar esperanza de vida, prevenir transmisiones de VIH, y ser costo-efectivas.

Case reduction and cost-effectiveness of the RTS,S/AS01 malaria vaccine alongside bed nets in Lilongwe, Malawi.

BACKGROUND: RTS,S/AS01, the most advanced vaccine against malaria, is now undergoing pilot implementation in Malawi, Ghana, and Kenya where an estimated 360,000 children will be vaccinated each year. In this study we evaluate RTS,S/AS01 alongside bed net use and estimate cost-effectiveness. METHODS: RTS,S/AS01 phase III trial and bed net prevalence data were used to determine the effect of vaccination in the urban/periurban and rural areas of Lilongwe, Malawi. Cost data were used to calculate the cost-effectiveness of various interventions over three years. FINDINGS: Since bed nets reduce malaria incidence and homogeneous vaccine efficacy was assumed, participants without bed nets received greater relative benefit from vaccination with RTS,S/AS01 than participants with bed nets. Similarly, since malaria incidence in rural Lilongwe is higher than in urban Lilongwe, the impact and cost-effectiveness of vaccine interventions is increased in rural areas. In rural Lilongwe, we estimated that vaccinating one child without a bed net would prevent 2·59 (1·62 to 3·38) cases of malaria over three years, corresponding to a cost of $10·08 (7·71 to 16·13) per case averted. Alternatively, vaccinating one child with a bed net would prevent 1·59 (0·87 to 2·57) cases, corresponding to $16·43 (10·16 to 30·06) per case averted. Providing RTS,S/AS01 to 30,000 children in rural Lilongwe was estimated to cost $782,400 and to prevent 58,611 (35,778 to 82,932) cases of malaria over a three-year period. Joint interventions providing both vaccination and bed nets (to those without them) were estimated to prevent additional cases of malaria and to be similarly cost-effective, compared to vaccine-only interventions. INTERPRETATION: To maximize malaria prevention, vaccination and bed net distribution programs could be integrated. FUNDING: Impacts of Environment, Host Genetics and Antigen Diversity on Malaria Vaccine Efficacy (1R01AI137410-01).

Precise and accurate power of the rank-sum test for a continuous outcome.

Accurate power calculations are essential in small studies containing expensive experimental units or high-stakes exposures. Herein, power of the Wilcoxon Mann-Whitney rank-sum test of a continuous outcome is formulated using a Monte Carlo approach and defining [Formula: see text] as a measure of effect size, where [Formula: see text] and [Formula: see text] denote random observations from two distributions hypothesized to be equal under the null. Effect size [Formula: see text] fosters productive communications because researchers understand [Formula: see text] is analogous to a fair coin toss, and [Formula: see text] near 0 or 1 represents a large effect. This approach is feasible even without background data. Simulations were conducted comparing the empirical power approach to existing approaches by Rosner & Glynn, Shieh and colleagues, Noether, and O'Brien-Castelloe. Approximations by Noether and O'Brien-Castelloe are shown to be inaccurate for small sample sizes. The Rosner & Glynn and Shieh, Jan & Randles approaches performed well in many small sample scenarios, though both are restricted to location-shift alternatives and neither approach is theoretically justified for small samples. The empirical method is recommended and available in the R package wmwpow.

Reimagining Health Communication: A Noninferiority Randomized Controlled Trial of Crowdsourced Intervention in China.

BACKGROUND: Crowdsourcing, the process of shifting individual tasks to a large group, may be useful for health communication, making it more people-centered. We aimed to evaluate whether a crowdsourced video is noninferior to a social marketing video in promoting condom use. METHODS: Men who have sex with men (≥16 years old, had condomless sex within 3 months) were recruited and randomly assigned to watch 1 of the 2 videos in 2015. The crowdsourced video was developed through an open contest, and the social marketing video was designed by using social marketing principles. Participants completed a baseline survey and follow-up surveys at 3 weeks and 3 months postintervention. The outcome was compared with a noninferiority margin of +10%. RESULTS: Among the 1173 participants, 907 (77%) and 791 (67%) completed the 3-week and 3-month follow-ups. At 3 weeks, condomless sex was reported by 146 (33.6%) of 434 participants and 153 (32.3%) 473 participants in the crowdsourced and social marketing arms, respectively. The crowdsourced intervention achieved noninferiority (estimated difference, +1.3%; 95% confidence interval, -4.8% to 7.4%). At 3 months, 196 (52.1%) of 376 individuals and 206 (49.6%) of 415 individuals reported condomless sex in the crowdsourced and social-marketing arms (estimated difference: +2.5%, 95% confidence interval, -4.5 to 9.5%). The 2 arms also had similar human immunodeficiency virus testing rates and other condom-related secondary outcomes. CONCLUSIONS: Our study demonstrates that crowdsourced message is noninferior to a social marketing intervention in promoting condom use among Chinese men who have sex with men. Crowdsourcing contests could have a wider reach than other approaches and create more people-centered intervention tools for human immunodeficiency virus control.

Predictors of Low Uptake of Prenatal Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis Immunization in Privately Insured Women in the United States.

OBJECTIVE: To examine the uptake of prenatal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) immunization among pregnant women in the United States. METHODS: Using MarketScan data, we conducted a historical cohort study among pregnant women with employer-based commercial insurance in the United States who delivered between January 1, 2010, and December 31, 2014. We examined temporal trends of uptake, predictors of uptake, and timing of Tdap immunization. RESULTS: Among 1,222,384 eligible pregnancies in 1,147,711 women, receipt of prenatal Tdap immunization increased from 0.0% of women who delivered in January 2010 to 9.8% who delivered in October 2012 (the date of the recommendation by the Advisory Committee on Immunization Practices for Tdap during every pregnancy) to 44.4% who delivered in December 2014. Among women who received Tdap during pregnancy, the majority were immunized between 27 weeks and 36 6/7 weeks of gestation per the Advisory Committee on Immunization Practices recommendation. In multivariable analyses among women who delivered between November 2012 and December 2014, rates of prenatal Tdap immunization were lower for women younger than 25 years of age (eg, 20-24 compared with 30-34 years rate ratio [RR] 0.83, 95% confidence interval [CI] 0.85-0.88), with other children (eg, three compared with zero children: RR 0.86, 95% CI 0.84-0.88), residing in the South compared with the Midwest (RR 0.81, 95% CI 0.80-0.82), or with emergency department visits in early pregnancy (RR 0.93, 95% CI 0.92-0.95). The proportion of pregnant women who received prenatal Tdap increased with increasing gestational age at birth. CONCLUSION: By the end of 2014, fewer than half of pregnant women in the United States were receiving prenatal Tdap immunization. Implementation and dissemination strategies are needed to increase Tdap coverage among pregnant women, especially those who are young, have other children, or reside in the South.

Comparing the effectiveness of a crowdsourced video and a social marketing video in promoting condom use among Chinese men who have sex with men: a study protocol.

INTRODUCTION: Crowdsourcing has been used to spur innovation and increase community engagement in public health programmes. Crowdsourcing is the process of giving individual tasks to a large group, often involving open contests and enabled through multisectoral partnerships. Here we describe one crowdsourced video intervention in which a video promoting condom use is produced through an open contest. The aim of this study is to determine whether a crowdsourced intervention is as effective as a social marketing intervention in promoting condom use among high-risk men who have sex with men (MSM) and transgender male-to-female (TG) in China. METHOD: We evaluate videos developed by crowdsourcing and social marketing. The crowdsourcing contest involved an open call for videos. Entries were judged on capacity to promote condom use, to be shareable or 'go viral' and to give value to the individual. 1170 participants will be recruited for the randomised controlled trial. Participants need to be MSM age 16 and over who have had condomless anal sex in the last 3 months. Recruitment will be through an online banner ad on a popular MSM web page and other social media platforms. After completing an initial survey, participants will be randomly assigned to view either the social marketing video or the crowdsourcing video. Follow-up surveys will be completed at 3 weeks and 3 months after initial intervention to evaluate condomless sex and related secondary outcomes. Secondary outcomes include condom social norms, condom negotiation, condom self-efficacy, HIV/syphilis testing, frequency of sex acts and incremental cost. ETHICS AND DISSEMINATION: Approval was obtained from the ethical review boards of the Guangdong Provincial Center for Skin Diseases and STI Control, UNC and UCSF. The results of this trial will be made available through publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT02516930.

Crowdsourcing HIV Test Promotion Videos: A Noninferiority Randomized Controlled Trial in China.

BACKGROUND: Crowdsourcing, the process of shifting individual tasks to a large group, may enhance human immunodeficiency virus (HIV) testing interventions. We conducted a noninferiority, randomized controlled trial to compare first-time HIV testing rates among men who have sex with men (MSM) and transgender individuals who received a crowdsourced or a health marketing HIV test promotion video. METHODS: Seven hundred twenty-one MSM and transgender participants (≥16 years old, never before tested for HIV) were recruited through 3 Chinese MSM Web portals and randomly assigned to 1 of 2 videos. The crowdsourced video was developed using an open contest and formal transparent judging while the evidence-based health marketing video was designed by experts. Study objectives were to measure HIV test uptake within 3 weeks of watching either HIV test promotion video and cost per new HIV test and diagnosis. RESULTS: Overall, 624 of 721 (87%) participants from 31 provinces in 217 Chinese cities completed the study. HIV test uptake was similar between the crowdsourced arm (37% [114/307]) and the health marketing arm (35% [111/317]). The estimated difference between the interventions was 2.1% (95% confidence interval, -5.4% to 9.7%). Among those tested, 31% (69/225) reported a new HIV diagnosis. The crowdsourced intervention cost substantially less than the health marketing intervention per first-time HIV test (US$131 vs US$238 per person) and per new HIV diagnosis (US$415 vs US$799 per person). CONCLUSIONS: Our nationwide study demonstrates that crowdsourcing may be an effective tool for improving HIV testing messaging campaigns and could increase community engagement in health campaigns. CLINICAL TRIALS REGISTRATION: NCT02248558.

Analysis of repeated low-dose challenge studies.

Preclinical evaluation of candidate human immunodeficiency virus (HIV) vaccines entails challenge studies whereby non-human primates such as macaques are vaccinated with either an active or control vaccine and then challenged (exposed) with a simian-version of HIV. Repeated low-dose challenge (RLC) studies in which each macaque is challenged multiple times (either until infection or some maximum number of challenges is reached) are becoming more common in an effort to mimic natural exposure to HIV in humans. Statistical methods typically employed for the testing for a vaccine effect in RLC studies include a modified version of Fisher's exact test as well as large sample approaches such as the usual log-rank test. Unfortunately, these methods are not guaranteed to provide a valid test for the effect of vaccination. On the other hand, valid tests for vaccine effect such as the exact log-rank test may not be easy to implement using software available to many researchers. This paper details which statistical approaches are appropriate for the analysis of RLC studies, and how to implement these methods easily in SAS or R.

Marginal structural models for case-cohort study designs to estimate the association of antiretroviral therapy initiation with incident AIDS or death.

To estimate the association of antiretroviral therapy initiation with incident acquired immunodeficiency syndrome (AIDS) or death while accounting for time-varying confounding in a cost-efficient manner, the authors combined a case-cohort study design with inverse probability-weighted estimation of a marginal structural Cox proportional hazards model. A total of 950 adults who were positive for human immunodeficiency virus type 1 were followed in 2 US cohort studies between 1995 and 2007. In the full cohort, 211 AIDS cases or deaths occurred during 4,456 person-years. In an illustrative 20% random subcohort of 190 participants, 41 AIDS cases or deaths occurred during 861 person-years. Accounting for measured confounders and determinants of dropout by inverse probability weighting, the full cohort hazard ratio was 0.41 (95% confidence interval: 0.26, 0.65) and the case-cohort hazard ratio was 0.47 (95% confidence interval: 0.26, 0.83). Standard multivariable-adjusted hazard ratios were closer to the null, regardless of study design. The precision lost with the case-cohort design was modest given the cost savings. Results from Monte Carlo simulations demonstrated that the proposed approach yields approximately unbiased estimates of the hazard ratio with appropriate confidence interval coverage. Marginal structural model analysis of case-cohort study designs provides a cost-efficient design coupled with an accurate analytic method for research settings in which there is time-varying confounding.

Risk assessment and clinical impact of liquid-based cytology, oncogenic human papillomavirus (HPV) DNA and mRNA testing in primary cervical cancer screening (the FASE study).

OBJECTIVE: New commercial HPV RNA assays require further validation studies in population-based cervical cancer screening settings. To assess the performance of (FDA-approved) APTIMA® HPV Assay (AHPV), Hybrid Capture 2 (HC2), in-house PCR genotyping, and ThinPrep LBC in population-based screening, stratified by three histological gold standards. STUDY DESIGN: A multi-center trial in 5006 women undergoing routine screening in France was designed to compare the absolute and relative risks of diagnosing CIN3+ and CIN2+ lesions by different diagnostic tests. RESULTS: Reproducibility between the primary and second pathology reading was excellent for CIN3+ and CIN2+ endpoints (Cohen's kappa 0.948 and 0.854). Absolute risks (PPV) of different tests (AHPV, HC2, PCR genotyping, LBC) in diagnosing CIN2+ (15-20%) and CIN3+ (4-6%) were similar for the first, second, and consensus pathology readings. The relative risks of diagnosing these lesions by the four tests were also similar when the first, second or third pathology readings were employed. AHPV had the highest absolute risk of both histological endpoints, and detects 5% to 15% more CIN3+ and CIN2+ lesions, respectively, than LBC. Compared with HC2 assay, the relative risk of AHPV is 24% to 29% higher, with a significant difference in CIN2+ detection. With LBC as reference, AHPV had the best sensitivity/specificity balance measured by AUC (area under ROC curve) comparison test (significant for CIN2+), and the colposcopy referral rate (9.2%) comparable to that of LBC (8.7%). CONCLUSIONS: These data corroborate the suitability of AHPV for the primary cervical cancer screening.

Group testing for case identification with correlated responses.

This article examines group testing procedures where units within a group (or pool) may be correlated. The expected number of tests per unit (i.e., efficiency) of hierarchical- and matrix-based procedures is derived based on a class of models of exchangeable binary random variables. The effect on efficiency of the arrangement of correlated units within pools is then examined. In general, when correlated units are arranged in the same pool, the expected number of tests per unit decreases, sometimes substantially, relative to arrangements that ignore information about correlation.

Optimizing screening for acute human immunodeficiency virus infection with pooled nucleic acid amplification tests.

Recent studies have shown the public health importance of identifying individuals with acute human immunodeficiency virus infection (AHI); however, the cost of nucleic acid amplification testing (NAAT) makes individual testing of at-risk individuals prohibitively expensive in many settings. Pooled NAAT (or group testing) can improve efficiency and test performance of testing for AHI, but optimizing the pooling algorithm can be difficult. We developed simple, flexible biostatistical models of specimen pooling with NAAT for the identification of AHI cases; these models incorporate group testing theory, operating characteristics of biological assays, and a model of viral dynamics during AHI. Pooling algorithm sensitivity, efficiency (test kits used per individual specimen evaluated), and positive predictive value (PPV) were modeled and compared for three simple pooling algorithms: two-stage minipools (D2), three-stage hierarchical pools (D3), and square arrays with master pools (A2m). We confirmed the results by stochastic simulation and produced reference tables and a Web calculator to facilitate pooling by investigators without specific biostatistical expertise. All three pooling strategies demonstrated improved efficiency and PPV for AHI case detection compared to individual NAAT. D3 and A2m algorithms generally provided better efficiency and PPV than D2; additionally, A2m generally exhibited better PPV than D3. Used selectively and carefully, the simple models developed here can guide the selection of a pooling algorithm for the detection of AHI cases in a wide variety of settings.

Sensitivity analysis for the assessment of causal vaccine effects on viral load in HIV vaccine trials.

Vaccines with limited ability to prevent HIV infection may positively impact the HIV/AIDS pandemic by preventing secondary transmission and disease in vaccine recipients who become infected. To evaluate the impact of vaccination on secondary transmission and disease, efficacy trials assess vaccine effects on HIV viral load and other surrogate endpoints measured after infection. A standard test that compares the distribution of viral load between the infected subgroups of vaccine and placebo recipients does not assess a causal effect of vaccine, because the comparison groups are selected after randomization. To address this problem, we formulate clinically relevant causal estimands using the principal stratification framework developed by Frangakis and Rubin (2002, Biometrics 58, 21-29), and propose a class of logistic selection bias models whose members identify the estimands. Given a selection model in the class, procedures are developed for testing and estimation of the causal effect of vaccination on viral load in the principal stratum of subjects who would be infected regardless of randomization assignment. We show how the procedures can be used for a sensitivity analysis that quantifies how the causal effect of vaccination varies with the presumed magnitude of selection bias.