Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Vera Halpern is active.

Publication


Featured researches published by Vera Halpern.


Cochrane Database of Systematic Reviews | 2013

Strategies to improve adherence and acceptability of hormonal methods of contraception

Vera Halpern; Laureen M Lopez; David A. Grimes; Laurie L Stockton

BACKGROUNDnWorldwide, hormonal contraceptives are among the most popular reversible contraceptives. Despite their high theoretical effectiveness, typical use results in much lower effectiveness. In large part, this disparity reflects difficulties in adherence to the contraceptive regimen and low rates for long-term continuation.nnnOBJECTIVESnThe intent was to determine the effectiveness of ancillary counseling techniques to improve adherence to, and continuation of, hormonal methods of contraception.nnnSEARCH METHODSnThrough August 2013, we searched computerized databases for randomized controlled trials (RCTs) comparing client-provider interventions with standard family planning counseling. Sources included CENTRAL, MEDLINE, EMBASE, POPLINE, ClinicalTrials.gov and ICTRP. Earlier searches also included LILACS, PsycINFO, Dissertation Abstracts, African Index Medicus, and IMEMR.nnnSELECTION CRITERIAnWe included RCTs of an intensive counseling technique or other client-provider intervention compared to routine family planning counseling. Interventions included group motivation; structured, peer, or multi-component counseling; and intensive reminders of appointments or next dosing. Outcome measures were discontinuation, reasons for discontinuation, number of missed pills or on-time injections, and pregnancy.nnnDATA COLLECTION AND ANALYSISnOne author evaluated the titles and abstracts from the searches to determine eligibility. Two authors extracted data from the included studies. We calculated the Mantel-Haenszel odds ratio (OR) for dichotomous outcomes. For continuous variables, the mean difference (MD) was computed; RevMan uses the inverse variance approach. For all analyses, 95% confidence intervals (CI) were also computed. Since the studies identified differed in both interventions and outcome measures, we did not conduct a meta-analysis.nnnMAIN RESULTSnNine RCTs met our inclusion criteria. Five involved direct counseling; of those, two also provided multiple contacts by telephone. Four other trials provided intensive reminders, two of which also provided health education information. Three trials showed some benefit of the experimental intervention. In a counseling intervention, women who received repeated structured information about the injectable depot medroxyprogesterone acetate (DMPA) were less likely to discontinue the method by 12 months (OR 0.27; 95% CI 0.16 to 0.44) than women who had routine counseling. The intervention group was also less likely to discontinue due to menstrual disturbances (OR 0.20; 95% CI 0.11 to 0.37). Another trial showed a group with special counseling plus phone calls was more likely than the special-counseling group to report consistent use of oral contraceptives (OC) at 3 months (OR 1.41; 95% CI 1.06 to 1.87), though not at 12 months. The group with only special counseling did not differ significantly from those with standard care for any outcome. The third trial compared daily text-message reminders about OCs plus health information versus standard care. Women in the text-message group were more likely than the standard-care group to continue OC use by six months (OR 1.54; 95% CI 1.14 to 2.10). The text-message group was also more likely to avoid an interruption in OC use longer than seven days (OR 1.53; 95% CI 1.13 to 2.07).nnnAUTHORS CONCLUSIONSnOnly three trials showed some benefit of strategies to improve adherence and continuation. However, several had small sample sizes and six had high losses to follow up. The overall quality of evidence was considered moderate. The intervention type and intensity varied greatly across the studies. A combination of intensive counseling and multiple contacts and reminders may be needed to improve adherence and acceptability of contraceptive use. High-quality RCTs with adequate power and well-designed interventions could help identify ways to improve adherence to, and continuation of, hormonal contraceptive methods.


PLOS ONE | 2008

Effectiveness of Cellulose Sulfate Vaginal Gel for the Prevention of HIV Infection: Results of a Phase III Trial in Nigeria

Vera Halpern; Folasade Ogunsola; Ok Obunge; Chin-Hua Wang; Nneka Onyejepu; Oyinola Oduyebo; Doug Taylor; Linda McNeil; Neha Mehta; John Umo-Otong; Sakiru Otusanya; Tania Crucitti; Saïd Abdellati

Background This trial evaluated the safety and effectiveness of 6% cellulose sulfate vaginal gel in preventing male-to-female vaginal transmission of HIV, gonorrhea and chlamydial infection. Methods This Phase III, double-blind, randomized, placebo-controlled trial was conducted between November 2004 and March 2007 in Lagos and Port Harcourt, Nigeria. We enrolled 1644 HIV-antibody negative women at high risk of HIV acquisition. Study participants were randomized 1∶1 to cellulose sulfate or placebo and asked to use gel plus a condom for each act of vaginal intercourse over one year of follow-up. The participants were evaluated monthly for HIV, gonorrhea and chlamydial infection, and for adverse events. Results The trial was stopped prematurely after the data safety monitoring board of a parallel trial concluded that cellulose sulfate might be increasing the risk of HIV. In contrast, we observed fewer infections in the active arm (10) than on placebo (13), a difference that was nonetheless not statistically significant (HRu200a=u200a0.8, 95% CI 0.3–1.8; pu200a=u200a0.56). Rates of gonorrhea and chlamydial infection were lower in the CS group but the difference was likewise not statistically significant (HRu200a=u200a0.8, 95% CI 0.5–1.1; pu200a=u200a0.19 for the combined STI outcome). Rates of adverse events were similar across study arms. No serious adverse events related to cellulose sulfate use were reported. Conclusions Cellulose sulfate gel appeared to be safe in the evaluated study population but we found insufficient evidence that it prevented male-to-female vaginal transmission of HIV, gonorrhea or chlamydial infection. The early closure of the trial compromised the ability to draw definitive conclusions about the effectiveness of cellulose sulfate against HIV. Trial Registration ClinicalTrials.gov NCT00120770


Cochrane Database of Systematic Reviews | 2012

Steroid hormones for contraception in men

David A. Grimes; Laureen M Lopez; Vera Halpern; Kavita Nanda; Kenneth F. Schulz

BACKGROUNDnMale hormonal contraception has been an elusive goal. Administration of sex steroids to men can shut off sperm production through effects on the pituitary and hypothalamus. However, this approach also decreases production of testosterone, so add-back therapy is needed.nnnOBJECTIVESnTo summarize all randomized controlled trials (RCTs) of male hormonal contraception.nnnSEARCH METHODSnIn January and February 2012, we searched the computerized databases CENTRAL, MEDLINE, POPLINE, and LILACS. We also searched for recent trials in ClinicalTrials.gov and ICTRP. Previous searches included EMBASE. We wrote to authors of identified trials to seek additional unpublished or published trials.nnnSELECTION CRITERIAnWe included all RCTs that compared a steroid hormone with another contraceptive. We excluded non-steroidal male contraceptives, such as gossypol. We included both placebo and active-regimen control groups.nnnDATA COLLECTION AND ANALYSISnThe primary outcome measure was the absence of spermatozoa on semen examination, often called azoospermia. Data were insufficient to examine pregnancy rates and side effects.nnnMAIN RESULTSnWe found 33 trials that met our inclusion criteria. The proportion of men who reportedly achieved azoospermia or had no detectable sperm varied widely. A few important differences emerged. 1) Levonorgestrel implants (160 μg daily) combined with injectable testosterone enanthate (TE) were more effective than levonorgestrel 125 µg daily combined with testosterone patches. 2) Levonorgestrel 500 μg daily improved the effectiveness of TE 100 mg injected weekly. 3) Levonorgestrel 250 μg daily improved the effectiveness of testosterone undecanoate (TU) 1000 mg injection plus TU 500 mg injected at 6 and 12 weeks. 4) Desogestrel 150 μg was less effective than desogestrel 300 μg (with testosterone pellets). 5) TU 500 mg was less likely to produce azoospermia than TU 1000 mg (with levonorgestrel implants). 6) Norethisterone enanthate 200 mg with TU 1000 mg led to more azoospermia when given every 8 weeks versus 12 weeks. 7) Four implants of 7-alpha-methyl-19-nortestosterone (MENT) were more effective than two MENT implants. We did not conduct any meta-analysis due to intervention differences.Several trials showed promising efficacy in percentages with azoospermia. Three examined desogestrel and testosterone preparations or etonogestrel and testosterone, and two examined levonorgestrel and testosterone.nnnAUTHORS CONCLUSIONSnNo male hormonal contraceptive is ready for clinical use. Most trials were small exploratory studies. Their power to detect important differences was limited and their results imprecise. In addition, assessment of azoospermia can vary by sensitivity of the method used. Future trials need more attention to the methodological requirements for RCTs. More trials with adequate power would also be helpful.


Cochrane Database of Systematic Reviews | 2014

REPEATED USE OF PRE- AND POSTCOITAL HORMONAL CONTRACEPTION FOR PREVENTION OF PREGNANCY

Vera Halpern; Elizabeth G. Raymond; Laureen M Lopez

BACKGROUNDnRepeated use of postcoital hormonal contraception is not currently recommended due to the higher risk of side effects and lower contraceptive effectiveness compared to other modern methods of contraception. However, emerging evidence indicates renewed interest in a regular coitally-dependent method of oral contraception. We evaluated the existing data on safety and effectiveness of pericoital use of levonorgestrel and other hormonal drugs to prevent pregnancy.nnnOBJECTIVESnTo determine the effectiveness and safety of repeated use of pre- and postcoital hormonal contraception for pregnancy prevention.nnnSEARCH METHODSnWe searched until 1 September 2014 for trials that tested repeated pre- and postcoital use of hormonal drugs for pregnancy prevention. Databases included CENTRAL, MEDLINE, and POPLINE. We searched for current trials via ClinicalTrials.gov and ICTRP. For the initial review, we also searched EMBASE, CINAHL, and LILACS, and wrote to researchers to identify other trials.nnnSELECTION CRITERIAnWe considered published and unpublished studies of repeated postcoital or immediately precoital use of hormonal drugs for contraception with pregnancy as an outcome.nnnDATA COLLECTION AND ANALYSISnTwo authors independently confirmed eligibility and extracted data from the included studies. We calculated confidence intervals (CI) around individual study Pearl indices using a Poisson distribution. We presented individual study estimates and pooled estimates and their 95% CI, where appropriate.nnnMAIN RESULTSnWe found 22 trials that evaluated pericoital use of LNG and other hormonal drugs on a regular basis to prevent pregnancy. The studies included a total of 12,400 participants, and were conducted in Europe, Asia, and the Americas. The drugs and doses evaluated included levonorgestrel (LNG) 0.75 mg (11 studies), LNG in doses other than 0.75 mg (4 trials), and hormones other than LNG (7 trials). Outcomes included pregnancy rates, discontinuation, side effects, and acceptability.Pericoital levonorgestrel was reasonably efficacious and safe. The pooled Pearl Index for the 0.75 mg dose of LNG was 5.4 per 100 woman-years (95% CI 4.1 to 7.0). The pooled Pearl Index for all doses of LNG was 5.0 per 100 woman-years (95% CI 4.4 to 5.6). Other hormonal drugs appeared promising but most of them were not studied extensively. Menstrual irregularities were the most common side effects reported. However, the studies provided no consistent evidence of a relationship between bleeding abnormalities and either frequency of pill intake or total dose of the drug. Non-menstrual side effects were reportedly mild and not tabulated in most studies. Most women liked the pericoital method in spite of frequent menstrual irregularities.nnnAUTHORS CONCLUSIONSnThe studies of pericoital LNG regimens provided promising results but many had serious methodological issues.xa0Most reports were decades old and provided limited information. However, we considered the evidence to be moderate quality because of the large number of participants from diverse populations, the low pregnancy rates, and the consistent results across studies. Rigorous research is still needed to confirm the efficacy and safety of pericoital use of LNG as a primary means of contraception among women with infrequent intercourse. If the method is shown to be efficacious, safe and acceptable, the results may warrant revision of the current World Health Organization recommendations and marketing strategies.


Contraception | 2012

Pharmacokinetics of subcutaneous depot medroxyprogesterone acetate injected in the upper arm

Vera Halpern; Stephanie Combes; Laneta Dorflinger; Debra H. Weiner; David F. Archer

BACKGROUNDnThe abdomen and thigh are recommended injection sites in the label for Depo-SubQ Provera 104™. We evaluated the pharmacokinetic profile of medroxyprogesterone acetate (MPA) following injection of Depo-SubQ Provera 104 in the upper arm, a preferred injection site in developing countries.nnnSTUDY DESIGNnTwenty-six women in Norfolk, VA, received a single injection of Depo-SubQ Provera 104 in the upper arm in this prospective noncomparative study. We measured MPA serum concentrations prior to injection (day 1) and 11 times postinjection (days 2, 4, 8, 14, 30, 44, 60, 74, 91, 104 and 120).nnnRESULTSnSerum MPA levels peaked at 0.953 ng/mL 2-14 days (interquartile range; median=8) after dosing. Mean AUC0-91 was 45.1 ng·day/mL. Mean MPA levels at days 91, 104 and 120 were 0.427, 0.367 and 0.327 ng/mL, respectively. A total of 15 individual measurements of MPA were below 0.2 ng/mL. All women but one had MPA levels above 0.1 ng/mL on day 91.nnnCONCLUSIONSnInjection of Depo-SubQ Provera 104™ in the upper arm provided sufficient MPA levels for contraceptive protection for 3 months (13 weeks). The uptake and metabolism of MPA when injected in the upper arm may be different from the abdomen and thigh.


Cochrane Database of Systematic Reviews | 2013

Spermicide used alone for contraception

David A. Grimes; Laureen M Lopez; Elizabeth G. Raymond; Vera Halpern; Kavita Nanda; Kenneth F. Schulz

BACKGROUNDnSpermicides have been used as contraceptives for thousands of years. Despite this long use, only recently have studies examined the comparative efficacy and acceptability of these vaginal medications. Spermicides contain an active ingredient (most commonly nonoxynol-9) and a formulation used to disperse the product, such as foam or vaginal suppository.nnnOBJECTIVESnThis review examined all known randomized controlled trials of a spermicide used alone for contraception.nnnSEARCH METHODSnIn August 2013, we searched the following computerized databases for randomized controlled trials of spermicides for contraception: CENTRAL, MEDLINE, POPLINE, LILACS, EMBASE, ClinicalTrials.gov, and ICTRP. For the initial review, we examined the reference lists of trials found as well as those of review articles and textbook chapters.nnnSELECTION CRITERIAnWe included any trial of a commercial product used alone for contraception. Each included trial must have provided sufficient information to determine pregnancy rates.nnnDATA COLLECTION AND ANALYSISnTwo authors independently extracted information from the trials identified. We did not conduct a meta-analysis, since most trials had large losses to follow up. We entered the data into tables and presented the results descriptively.nnnMAIN RESULTSnWe located reports from 14 trials for the initial review, but have not identified any new trials since then. In the largest trial to date, the gel (Advantage S) containing the lowest dose of nonoxynol-9 (52.5 mg) was significantly less effective in preventing pregnancy than were gels with higher doses of the same agent (100 mg and 150 mg). Probabilities of pregnancy by six months were 22% for the 52.5 mg gel, 16% for the 100 mg dose, and 14% for the 150 mg dose. In the same trial, the three different vehicles with 100 mg of nonoxynol-9 had similar efficacy. Interpretation of these figures is limited, since 39% of participants discontinued the method or were lost from the trial. Few important differences in efficacy emerged in other trials.nnnAUTHORS CONCLUSIONSnThe probability of pregnancy varied widely in reported trials. A gel containing nonoxynol-9 52.5 mg was inferior to two other products tested in the largest trial. Aside from this finding, personal characteristics and behavior of users may be more important than characteristics of the spermicide products in determining the probability of pregnancy. Gel was liked more than the film or vaginal suppository in the largest trial. Spermicide trials have the dual challenges of difficult recruitment and high discontinuation rates; the latter threatens trial validity.


Contraception | 2011

Predictors of pregnancy in microbicide trials

Vera Halpern; Che-Chin Lie; Paul J. Feldblum; Lut Van Damme

BACKGROUNDnHigh pregnancy rates undermine the conduct and interpretation of HIV prevention trials. We performed this analysis to identify baseline participant characteristics associated with increased risk of pregnancy in recent vaginal microbicide trials.nnnSTUDY DESIGNnWe analyzed the data from four recently completed Phase III trials of candidate microbicides for prevention of HIV infection. Cox proportional hazard models, stratified by site nested within study, were used to determine the baseline factors that predict pregnancy. Six thousand seven hundred forty-eight women contributed data for this analysis.nnnRESULTSnPregnancies were detected in a total of 1826 (27.1%) women. The hazard of pregnancy was higher for women who had a history of pregnancy, were living with a man or reported more sexual acts not protected by condoms in the week prior to enrollment. The risk of pregnancy was lower in older participants; in women with more years of education; in women who reported more sexual partners at baseline interview; in women who reported using intrauterine contraception, implants, sterilization or injectables and in women who reported use of a condom during their last act of vaginal intercourse.nnnCONCLUSIONSnOur data suggest that current use or acceptance of intrauterine contraception, implants, sterilization or injectables is the most effective approach to reduce pregnancy rates and might be a useful eligibility criterion in future HIV prevention trials.


Contraception | 2008

The effects of spermicides containing nonoxynol-9 on cervical cytology.

Vera Halpern; Wes Rountree; Elizabeth G. Raymond; May Law

BACKGROUNDnThis analysis was undertaken to compare the effect of the different dosages and formulations of spermicides containing nonoxynol-9 (N-9) on cervical cytology.nnnSTUDY DESIGNnA randomized trial was conducted at 14 sites in the United States to evaluate the effectiveness and safety of five spermicides containing N-9. This Papanicolaou smear analysis included the data from all participants who provided two Papanicolaou smear samples: at admission and after discontinuation of the product. The effects of the spermicides were evaluated by comparing the rates of alteration of cervical cytology between five study groups.nnnRESULTSnA total of 640 women were included in this analysis. The majority of the study participants (>85%) had no change of their baseline Papanicolaou smear result. The rates of alteration of cervical cytology were similar among women using the three gels containing the different doses of N-9 and three different formulations containing the same dose of N-9. Our analysis found no association between alteration of cervical cytology and duration or frequency of use of the five study spermicides.nnnCONCLUSIONSnExposure to different formulations and doses of spermicides containing N-9 is unlikely to influence cervical cytology.


Contemporary Clinical Trials | 2011

What predicts non-retention in microbicide trials?

Paul J. Feldblum; Vera Halpern; Che-Chin Lie; Ok Obunge; Folasade Ogunsola; William Ampofo; Kofi Opoku

BACKGROUNDnPoor retention can reduce study power and thwart randomization, possibly resulting in biased estimates of effect. Some HIV prevention trials conducted in developing countries have been challenged by high loss to follow-up. Identifying factors associated with non-retention could lead to recruitment of women more likely to remain in the trial, potentially yielding greater efficiency and validity.nnnMETHODSnWe summarized retention rates and, using Cox regression, evaluated factors associated with non-retention in four trials of two candidate vaginal microbicides (1% C31G or SAVVY® and 6% cellulose sulfate or CS) conducted in multiple sub-Saharan African countries. We defined retention as completion of the trial, including those with an HIV outcome. Non-retention comprised participants randomized to a study arm who were either lost to follow-up or discontinued prior to infection with HIV.nnnRESULTSn7,367 women were enrolled and randomized in the four trials; 7,086 are included in this analysis. 1,514 (21.4%) participants were either lost to follow-up or had early discontinuation. In the final Cox model, the following baseline factors were associated with non-retention: younger age (hazard ratio [HR] = 0.95); less education (HR = 0.97); condom use at last sex (HR = 1.18); larger number of sex acts in a typical week (HR = 1.01); and baseline candidiasis or bacterial vaginosis (HR = 1.12).nnnCONCLUSIONSnYounger and less educated women were more difficult to retain in these microbicide trials. But these same traits may be associated with higher HIV infection rates. Enhanced retention methods focused on those at highest risk of non-retention and possibly infection will optimize study efficiency and validity.


BMC Medical Research Methodology | 2009

Interim data monitoring to enroll higher-risk participants in HIV prevention trials

Vera Halpern; Orikomaba Obunge; Folasade Ogunsola; Sakiru Otusanya; John Umo-Otong; Chin-Hua Wang; Neha Mehta

BackgroundLower-than-expected incidence of HIV undermines sample size calculations and compromises the power of a HIV prevention trial. We evaluated the effectiveness of interim monitoring of HIV infection rates and on-going modification of recruitment strategies to enroll women at higher risk of HIV in the Cellulose Sulfate Phase III study in Nigeria.MethodsWe analyzed prevalence and incidence of HIV and other sexually transmitted infections, demographic and sexual behavior characteristics aggregated over the treatment groups on a quarterly basis. The site investigators were advised on their recruitment strategies based on the findings of the interim analyses.ResultsA total of 3619 women were screened and 1644 enrolled at the Ikeja and Apapa clinics in Lagos, and at the Central and Peripheral clinics in Port Harcourt. Twelve months after study initiation, the overall incidence of HIV was less than one-third of the pre-study assumption, with rates of HIV that varied substantially between clinics. Due to the low prevalence and incidence rates of HIV, it was decided to close the Ikeja clinic in Lagos and to find new catchment areas in Port Harcourt. This strategy was associated with an almost two-fold increase in observed HIV incidence during the second year of the study.ConclusionGiven the difficulties in estimating HIV incidence, a close monitoring of HIV prevalence and incidence rates during a trial is warranted. The on-going modification of recruitment strategies based on the regular analysis of HIV rates appeared to be an efficient method for targeting populations at greatest risk of HIV infection and increasing study power in the Nigeria trial.Trial RegistrationThe trial was registered with the ClinicalTrials.gov registry under #NCT00120770 http://clinicaltrials.gov/ct2/show/NCT00120770

Collaboration


Dive into the Vera Halpern's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Kenneth F. Schulz

University of North Carolina at Chapel Hill

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge