Navigating COVID-19 and related challenges to completing clinical trials: Lessons from the PATRIOT and STEP-UP randomized prevention trials

BACKGROUND/AIMS

High follow-up is critical in randomized clinical trials. We developed novel approaches to modify in-person visits and complete follow-up during COVID-19. Since these strategies are broadly applicable to circumstances wherein follow-up is difficult, they may help in contingency planning. The objective of this article is to develop and evaluate new approaches to replace detailed, in-person study visits for two trials focused on preventing diabetic foot complications.

METHODS

A quasi-experimental pre-post design compared approaches for follow-up during COVID-19 to approaches pre-COVID-19. Study subjects were outpatients at two Veterans Affairs Medical Centers. Following a research "hold," research resumed in February 2021 for Self-monitoring, Thermometry and Educating Patients for Ulcer Prevention (STEP UP) (n = 241), which focused on preventing recurrent foot ulcers, and in April 2021 for Preventing Amputation by Tailored Risk-based Intervention to Optimize Therapy (PATRIOT) (n = 406), which focused on preventing pre-ulcerative and ulcerative lesions. To complete data collection, we shortened visits, focused on primary and secondary outcomes, and conducted virtual visits when appropriate. For STEP UP, we created a 20-min assessment process that could be administered by phone. Since PATRIOT required plantar photographs to assess foot lesions, we conducted short face-to-face visits. We explored differences and assessed proportion completing visit, visit completion/100 person-months and compared COVID-19 to pre- COVID-19 using unadjusted risk ratios, incidence rate ratios, all with associated 95% confidence intervals (CIs). Finally, we report time-to-visit curves.

RESULTS

In both studies, participants whose follow-up concluded pre- COVID-19 seemed older than those whose follow-up concluded during COVID-19 (PATRIOT: 68.0 (67.2, 68.9) versus 65.2 years (61.9, 68.5); STEP UP: 67.5 (66.2, 68.9) versus 65.3 (63.3, 67.3)). For STEP UP, we completed 91 visits pre- COVID-19 (37.8% (31.6%, 44.2%)) and 63 visits during COVID-19 (78.8% (68.2%, 87.1%)). This was over 1309 person-months pre-COVID-19, and over 208.8 person-months during COVID-19; the visit completion rate/100 person-months were: pre-COVID-19 7.0 (5.6, 8.5), COVID-19 30.2 (23.2, 38.6); risk ratio: 2.1 (1.7, 2.5); and incidence rate ratio 4.3 (3.1, 5.9). Similarly, for PATRIOT, we completed 316 visits pre-COVID-19 (77.8% (73.5%, 81.8%)) and 27 assessments during COVID-19 (84.4% (67.2%, 94.7%)). This was over 1192.7 person-months pre-COVID-19 and 39.3 person-months during COVID-19. The visit completion rate/100 person-months in PATRIOT were: pre-COVID-19 2.7 (2.4, 3.0), COVID-19 6.9 (4.5, 10); risk ratio 1.1 (0.9, 1.3); incidence rate ratio 2.6 (1.8, 3.8). For both studies, the follow-up curves began separating at < 2 months.

CONCLUSIONS

We achieved higher completion rates during COVID-19 compared to pre-COVID-19 by modifying visits and focusing on primary and secondary outcomes. These strategies prevent excessive missing data, support more valid conclusions, and improve efficiency. They may provide important alternative strategies to achieving higher follow-up in randomized clinical trials.

Challenges to Recruiting Men on Active Surveillance for Prostate Cancer in Clinical Chemoprevention Trials

Clinical trials play a critical role in evidence-based medicine, when rigorous scientific methodology is utilized to discover and test the effectiveness and safety of new drugs to prevent or cure diseases, including cancer. Participation in clinical trials thus becomes key to successful completion of these trials. Although it is estimated that >70% of Americans are inclined to participate in clinical trials, less than 5% of adult cancer patients participate in clinical trials. There is thus a large gap between those inclined to participate in clinical trials and actual participation in clinical trials. As with trials targeting men with prostate cancer (PCa) on active surveillance (AS), where the target population is mostly over 50 years of age, others have observed several challenges with recruitment and accrual in clinical trials. The participation rate is currently unavailable for men on primary and secondary chemoprevention trials. Additionally, with unanticipated environmental factors such as a pandemic or other natural emergencies that may severely impact the economy, personal property, travel and person-to person contact for study-related procedures, there is a need to continuously identify these challenges and determine solutions to recruitment barriers in chemoprevention trials to ensure timely completion of early phase trials. Recent studies regarding the impact of the pandemic on clinical trial recruitment have shown that cancer prevention trials were relatively more negatively impacted compared to cancer treatment trials. The goal of this manuscript is to review our experience in continuously evaluating the protocol and patient level challenges to recruiting subjects on AS for PCa in this cancer chemoprevention trial conducted at the Comprehensive Cancer Center (CCC) and report the contemporary strategies that we are utilizing to continue to recruit subjects in this trial. We provide data from our current trial as an example while discussing future strategies to improve overall clinical trial recruitment. These strategies can inform future design of contemporary cancer chemoprevention trials and, additionally, better select, focus and invest in strategies that are the most productive and efficient for recruiting target populations.

Longitudinal Exposure-Response Modeling of Multiple Indicators of Alzheimer's Disease Progression

BACKGROUND

Progression in Alzheimer's disease manifests as changes in multiple biomarker, cognitive, and functional endpoints. Disease progression modeling can be used to integrate these multiple measures into a synthesized metric of where a patient lies within the disease spectrum, allowing for a more dynamic measure over the range of the disease.

OBJECTIVES

This study aimed to combine modeling techniques from psychometric research (e.g., item response theory) and pharmacometrics (e.g., hierarchical models) to describe the multivariate longitudinal disease progression for patients with mild-to-moderate Alzheimer's disease. Additionally, we aimed to extend the subsequent model to make it suitable for clinical trial simulation, with the inclusion of covariates, to explain variability in latent progression (i.e., disease progression) and to aid in the assessment of enrichment strategies.

DESIGN

Multiple longitudinal endpoints in the Alzheimer's Disease Neuroimaging Initiative database were modeled. This model was validated internally using visual predictive checks, and externally by comparing data from the placebo arms of two Phase 2 crenezumab studies, ABBY (NCT01343966) and BLAZE (NCT01397578).

SETTING

The Alzheimer's Disease Neuroimaging Initiative began in 2004: the initial 5-year study (ADNI-1) was extended by 2 years in 2009 by a Grand Opportunities grant (ADNI-GO), and in 2011 and 2016 by further competitive renewals of the ADNI-1 grant (ADNI-2 and ADNI-3, respectively). This work studies natural progression data from patients with confirmed Alzheimer's disease. The Phase 2 ABBY and BLAZE trials evaluated the safety and efficacy of crenezumab in patients with mild-to-moderate Alzheimer's disease.

PARTICIPANTS

From the Alzheimer's Disease Neuroimaging Initiative database, 305 subjects who had a baseline diagnosis of mild-to-moderate Alzheimer's disease were included in modeling. From the ABBY and BLAZE studies, 158 patients were included from the studies' placebo arms.

MEASUREMENTS

Longitudinal cognitive and functional assessments modeled included the Clinical Dementia Rating (both as Sum of Boxes and individual item scores), the Mini-Mental State Examination, the Alzheimer's Disease Assessment Scale - Cognitive Subscale, the Functional Activities Questionnaire, the Montreal Cognitive Assessment, and the Rey Auditory Verbal Learning Test. Also included were the imaging variable fluorodeoxyglucose-positron emission tomography and the following magnetic resonance imaging volumetrics: entorhinal, fusiform, hippocampal, intra-cranial, mid-temporal, ventricular, and whole brain.

RESULTS

Applying item response theory approaches in this longitudinal setting showed clinical assessments informing a common disease scale in the following order (from early disease to late disease): Rey Auditory Verbal Learning Test, Functional Activities Questionnaire, Montreal Cognitive Assessment, Alzheimer's Disease Assessment Scale - Cognitive Subscale 12, Clinical Dementia Rating - Sum of Boxes, and Mini-Mental State Examination. The Clinical Dementia Rating communication and home-and-hobbies items were most informative at earlier disease stages, while memory, orientation, and personal care informed the disease status at later stages. A clinical trial simulation model was developed and accurately described within-sample longitudinal distribution of endpoints. Simplifying the model to use only baseline age, MMSE, and APOEε4 status as predictors, out-of-sample mean progression of ADAS-Cog and CDR Sum of Boxes in the ABBY and BLAZE placebo arms was accurately described; however, the variability in these endpoints was underpredicted and suggests possibility for further model refinement when extrapolating from the ADNI sample to trial data. Clinical trial simulations were performed to exemplify use of the model to investigate hypothetical disease modification effects on the multivariate, longitudinal progression on the Alzheimer's Disease Assessment Scale - Cognitive Subscale and the Clinical Dementia Rating - Sum of Boxes.

CONCLUSIONS

The latent variable structure of item response theory can be extended to capture a variety of scales that are common assessments and indicators of disease status in mild-to-moderate Alzheimer's disease. These models are not intended to support causal inferences, but they do successfully characterize the observed correlation between endpoints over time and result in concise numerical indices of disease status that reflect the totality of evidence from considering the endpoints jointly. As such, the models have utility for a variety of tasks in clinical trial design, including simulation of hypothetical drug effects, interpolation of missing data, and assessment of in-sample information.

Impact of Measurement Variability on Study Inference in Partner Violence Prevention Trials in Low- and Middle-Income Countries

In lower- and middle-income countries (LMICs), studies of interventions to reduce intimate partner violence (IPV) are expanding, yet measurement equivalence of the IPV construct-the primary outcome in these investigations-has not been established. We assessed the measurement equivalence of physical and sexual IPV item sets used in recent trials in LMICs and tested the impact of noninvariance on study inference. With data from four intervention trials (N = 3,545) completed before 2020, we used multiple-group confirmatory factor analysis to assess invariance across arms, over time, and across studies. We also calculated average treatment effects adjusting for covariate imbalance to assess concordance with published results. Most items functioned equivalently within studies at baseline and end line. Some evidence of longitudinal noninvariance was observed in at least one study arm in three studies, but did not meaningfully affect latent means or effect-size estimates. Evidence of partial invariance across studies at baseline and strict invariance over time was observed. Common measures of physical and sexual IPV were valid for measuring intervention impact in these samples. The study highlights the need for harmonized use of the tested scale, content validity assessments, and routine measurement equivalence testing to ensure valid inferences about intervention effectiveness.

Probing the Pre-diagnostic Phase of Parkinson's Disease in Population-Based Studies

Parkinson's disease covers a wide spectrum of symptoms, ranging from early non-motor symptoms to the characteristic bradykinesia, tremor and rigidity. Although differences in the symptomatology of Parkinson's disease are increasingly recognized, there is still a lack of insight into the heterogeneity of the pre-diagnostic phase of Parkinson's disease. In this perspective, we highlight three aspects regarding the role of population-based studies in providing new insights into the heterogeneity of pre-diagnostic Parkinson's disease. First we describe several specific advantages of population-based cohort studies, including the design which overcomes some common biases, the broad data collection and the high external validity. Second, we draw a parallel with the field of Alzheimer's disease to provide future directions to uncover the heterogeneity of pre-diagnostic Parkinson's disease. Finally, we anticipate on the emergence of prevention and disease-modification trials and the potential role of population-based studies herein. In the coming years, bridging gaps between study designs will be essential to make vital advances in elucidating the heterogeneity of pre-diagnostic Parkinson's disease.

Loss to follow-up among female sex workers in Zambia: findings from a five-year HIV-incidence cohort

HIV-incidence studies are used to identify at-risk populations for HIV-prevention trials and interventions, but loss to follow-up (LTFU) can bias results if participants who remain differ from those who drop out. We investigated the incidence of and factors associated with LTFU among Zambian female sex workers (FSWs) in an HIV-incidence cohort from 2012 to 2017. Enrolled participants returned at month one, month three and quarterly thereafter. FSWs were considered LTFU if they missed six consecutive months, or if their last visit was six months before the study end date. Of 420 FSWs, 139 (33%) were LTFU at a rate of 15.7 per 100 person years. In multivariable analysis, LTFU was greater for FSWs who never used alcohol, began sex work above the age of consent, and had a lower volume of new clients. Our study appeared to retain FSWs in most need of HIV-prevention services offered at follow-up.

Racial and ethnic differences in older adults' willingness to be contacted about Alzheimer's disease research participation

INTRODUCTION

We sought to examine the association of race/ethnicity with willingness to engage in studies that involve procedures typical of Alzheimer's disease (AD) clinical trials and determine whether any observed differences could be explained by research attitudes.

METHODS

We studied 2749 adults aged ≥50 years who enrolled in a community-based recruitment registry.

RESULTS

Compared to non-Hispanic (NH) whites (n = 2393, 87%), Hispanics (n = 191, 7%), NH Asians (n = 129, 5%) and NH blacks (n = 36, 1%) were 44%, 46%, and 64% less willing, respectively, to be contacted for studies that have requirements typical of AD prevention trials, namely: cognitive testing, brain imaging, blood draws, and investigational medications. Mediation by research attitudes was explored, but did not explain the observed differences.

DISCUSSION

Our findings suggest that ethnoracial minorities are less willing to engage in studies that are typical of AD prevention trials. Future work should focus on understanding the factors that drive these differences.

Design and sample size considerations for Alzheimer's disease prevention trials using multistate models

BACKGROUND/AIMS

Clinical trials for Alzheimer's disease have been aimed primarily at persons who have cognitive symptoms at enrollment. However, researchers are now recognizing that the pathophysiological process of Alzheimer's disease begins years, if not decades, prior to the onset of clinical symptoms. Successful intervention may require intervening early in the disease process. Critical issues arise in designing clinical trials for primary and secondary prevention of Alzheimer's disease including determination of sample sizes and follow-up duration. We address a number of these issues through application of a unifying multistate model for the preclinical course of Alzheimer's disease. A multistate model allows us to specify at which points during the long disease process the intervention exerts its effects.

METHODS

We used a nonhomogeneous Markov multistate model for the progression of Alzheimer's disease through preclinical disease states defined by biomarkers, mild cognitive impairment and Alzheimer's disease dementia. We used transition probabilities based on several published cohort studies. Sample size methods were developed that account for factors including the initial preclinical disease state of trial participants, the primary endpoint, age-dependent transition and mortality rates and specifications of which transition rates are the targets of the intervention.

RESULTS

We find that Alzheimer's disease prevention trials with a clinical primary endpoint of mild cognitive impairment or Alzheimer's disease dementia will require sample sizes of the order many thousands of individuals with at least 5 years of follow-up, which is larger than most Alzheimer's disease therapeutic trials conducted to date. The reasons for the large trial sizes include the long and variable preclinical period that spans decades, high rates of attrition among elderly populations due to mortality and losses to follow-up and potential selection effects, whereby healthier subjects enroll in prevention trials. A web application is available to perform sample size calculations using the methods reported here.

CONCLUSION

Sample sizes based on multistate models can account for the points in the disease process when interventions exert their effects and may lead to more accurate sample size determinations. We will need innovative strategies to help design Alzheimer's disease prevention trials with feasible sample size requirements and durations of follow-up.

Minimizing the Sample Sizes of Clinical Trials on Preclinical and Early Symptomatic Stage of Alzheimer Disease

BACKGROUND

Clinical trials of investigational drugs for Alzheimer disease (AD) increasingly focus on the prodromal (symptomatic) stage of the illness and now its preclinical (asymptomatic) stage. Sensitive and specific cognitive and functional endpoints are needed to track subtle cognitive and functional changes in the early and preclinical stages to minimize sample sizes in these trials.

OBJECTIVES

To identify informative items in a standard clinical assessment protocol and a psychometric battery that are predictive of onset of dementia symptom.

DESIGN

Longitudinal retrospective study.

SETTING

Washington University (WU) Knight Alzheimer Disease Research Center (ADRC).

PARTICIPANTS

A total of 735 individuals at least 65 years old and cognitively normal at baseline from a longitudinal clinical cohort at the WU Knight ADRC.

MEASUREMENTS

The annual clinical assessment included a wide spectrum of functional and cognitive domains; a comprehensive psychometric battery was completed about 2 weeks after the clinical evaluation. Psychometricians are blinded to the results of the clinical evaluation and to the prior performance of the participants on the psychometric tests.

RESULTS

The mean age at baseline of the 735 participants was 74.30 and 62.31% were female. 240 individuals developed prodromal dementia symptoms (consistent with mild cognitive impairment due to AD and with very mild AD dementia) during longitudinal follow-up (mean follow-up=6.79 years). Among a total of 562 items in the clinical and cognitive assessments under analysis, 292 (52%) were identified as informative because their longitudinal changes were predictive of symptomatic onset. When these items were used to form the functional and cognitive composites, the longitudinal rates of changes were free of a learning effect and captured subtle longitudinal progression prior to symptomatic onset. The rates of change were much greater right after the symptomatic onset than those from the functional and cognitive composites formed using non-informative items. Although the sample sizes for prevention trials (prior to symptomatic onset) using the informative items still yield large numbers, the sample sizes for early treatment trial (after symptomatic onset) was much smaller than those derived from all the items or from the non-informative items alone.

CONCLUSIONS

The antecedent longitudinal changes in nearly half of the items in a clinical assessment protocol and a comprehensive cognitive battery did not show statistically significant ability to predict the dementia symptom onset, and hence may be non-informative to track the preclinical functional and cognitive progression of AD. The remaining items, on the other hand, captured some of the preclinical changes prior to the symptom onset, but performed much better right after the symptom onset. Currently ongoing prevention trials on preclinical AD of elderly individuals may need to re-assess the sample sizes and statistical power.

Randomised trial of a parent-mediated intervention for infants at high risk for autism: longitudinal outcomes to age 3 years

BACKGROUND

There has been increasing interest in the potential for pre-emptive interventions in the prodrome of autism, but little investigation as to their effect.

METHODS

A two-site, two-arm assessor-blinded randomised controlled trial (RCT) of a 12-session parent-mediated social communication intervention delivered between 9 and 14 months of age (Intervention in the British Autism Study of Infant Siblings-Video Interaction for Promoting Positive Parenting), against no intervention. Fifty-four infants (28 intervention, 26 nonintervention) at familial risk of autism but not otherwise selected for developmental atypicality were assessed at 9-month baseline, 15-month treatment endpoint, and 27- and 39-month follow-up.

PRIMARY OUTCOME

severity of autism prodromal symptoms, blind-rated on Autism Observation Schedule for Infants or Autism Diagnostic Observation Schedule 2nd Edition across the four assessment points.

SECONDARY OUTCOMES

blind-rated parent-child interaction and child language; nonblind parent-rated communication and socialisation. Prespecified intention-to-treat analysis combined estimates from repeated measures within correlated regressions to estimate the overall effect of the infancy intervention over time.

RESULTS

Effect estimates in favour of intervention on autism prodromal symptoms, maximal at 27 months, had confidence intervals (CIs) at each separate time point including the null, but showed a significant overall effect over the course of the intervention and follow-up period (effect size [ES] = 0.32; 95% CI 0.04, 0.60; p = .026). Effects on proximal intervention targets of parent nondirectiveness/synchrony (ES = 0.33; CI 0.04, 0.63; p = .013) and child attentiveness/communication initiation (ES = 0.36; 95% CI 0.04, 0.68; p = .015) showed similar results. There was no effect on categorical diagnostic outcome or formal language measures.

CONCLUSIONS

Follow-up to 3 years of the first RCT of a very early social communication intervention for infants at familial risk of developing autism has shown a treatment effect, extending 24 months after intervention end, to reduce the overall severity of autism prodromal symptoms and enhance parent-child dyadic social communication over this period. We highlight the value of extended follow-up and repeat assessment for early intervention trials.

The Road Ahead to Cure Alzheimer's Disease: Development of Biological Markers and Neuroimaging Methods for Prevention Trials Across all Stages and Target Populations

Alzheimer's disease (AD) is a slowly progressing non-linear dynamic brain disease in which pathophysiological abnormalities, detectable in vivo by biological markers, precede overt clinical symptoms by many years to decades. Use of these biomarkers for the detection of early and preclinical AD has become of central importance following publication of two international expert working group's revised criteria for the diagnosis of AD dementia, mild cognitive impairment (MCI) due to AD, prodromal AD and preclinical AD. As a consequence of matured research evidence six AD biomarkers are sufficiently validated and partly qualified to be incorporated into operationalized clinical diagnostic criteria and use in primary and secondary prevention trials. These biomarkers fall into two molecular categories: biomarkers of amyloid-beta (Aβ) deposition and plaque formation as well as of tau-protein related hyperphosphorylation and neurodegeneration. Three of the six gold-standard ("core feasible) biomarkers are neuroimaging measures and three are cerebrospinal fluid (CSF) analytes. CSF Aβ1-42 (Aβ1-42), also expressed as Aβ1-42 : Aβ1-40 ratio, T-tau, and P-tau Thr181 & Thr231 proteins have proven diagnostic accuracy and risk enhancement in prodromal MCI and AD dementia. Conversely, having all three biomarkers in the normal range rules out AD. Intermediate conditions require further patient follow-up. Magnetic resonance imaging (MRI) at increasing field strength and resolution allows detecting the evolution of distinct types of structural and functional abnormality pattern throughout early to late AD stages. Anatomical or volumetric MRI is the most widely used technique and provides local and global measures of atrophy. The revised diagnostic criteria for "prodromal AD" and "mild cognitive impairment due to AD" include hippocampal atrophy (as the fourth validated biomarker), which is considered an indicator of regional neuronal injury. Advanced image analysis techniques generate automatic and reproducible measures both in regions of interest, such as the hippocampus and in an exploratory fashion, observer and hypothesis-indedendent, throughout the entire brain. Evolving modalities such as diffusion-tensor imaging (DTI) and advanced tractography as well as resting-state functional MRI provide useful additionally useful measures indicating the degree of fiber tract and neural network disintegration (structural, effective and functional connectivity) that may substantially contribute to early detection and the mapping of progression. These modalities require further standardization and validation. The use of molecular in vivo amyloid imaging agents (the fifth validated biomarker), such as the Pittsburgh Compound-B and markers of neurodegeneration, such as fluoro-2-deoxy-D-glucose (FDG) (as the sixth validated biomarker) support the detection of early AD pathological processes and associated neurodegeneration. How to use, interpret, and disclose biomarker results drives the need for optimized standardization. Multimodal AD biomarkers do not evolve in an identical manner but rather in a sequential but temporally overlapping fashion. Models of the temporal evolution of AD biomarkers can take the form of plots of biomarker severity (degree of abnormality) versus time. AD biomarkers can be combined to increase accuracy or risk. A list of genetic risk factors is increasingly included in secondary prevention trials to stratify and select individuals at genetic risk of AD. Although most of these biomarker candidates are not yet qualified and approved by regulatory authorities for their intended use in drug trials, they are nonetheless applied in ongoing clinical studies for the following functions: (i) inclusion/exclusion criteria, (ii) patient stratification, (iii) evaluation of treatment effect, (iv) drug target engagement, and (v) safety. Moreover, novel promising hypothesis-driven, as well as exploratory biochemical, genetic, electrophysiological, and neuroimaging markers for use in clinical trials are being developed. The current state-of-the-art and future perspectives on both biological and neuroimaging derived biomarker discovery and development as well as the intended application in prevention trials is outlined in the present publication.

Amyloid-directed monoclonal antibodies for the treatment of Alzheimer's disease: the point of no return?

INTRODUCTION

Two humanized monoclonal antibodies, bapineuzumab and solanezumab, directed against the N terminus and mid-region of β-amyloid (Aβ), respectively, were recently tested in large, long-term Phase III trials in patients with mild-to-moderate Alzheimer's disease (AD).

AREAS COVERED

This review discusses current clinical data on solanezumab, bapineuzumab and their failure in Phase III trials to show significant clinical benefits, as well as other monoclonal antibodies under investigation for AD.

EXPERT OPINION

Solanezumab showed some beneficial cognitive effects in mildly affected AD patients and this subgroup of AD patients is currently being tested in another Phase III trial to this subgroup of AD patients to confirm previous encouraging observations. Two other monoclonal antibodies, gantenerumab, which preferentially binds to fibrillar Aβ, and crenezumab, which preferentially binds to soluble, oligomeric and fibrillar Aβ deposits, are being tested in secondary prevention trials in presymptomatic subjects with autosomal dominant AD mutations. Solanezumab is also being tested in a prevention study in asymptomatic older subjects, who have positive positron emission tomography scans for brain amyloid deposits. These ongoing secondary prevention trials will tell us if Aβ really plays a crucial role in the pathophysiology of AD.

Anti-amyloid beta to tau - based immunization: Developments in immunotherapy for Alzheimer disease

Immunotherapy might provide an effective treatment for Alzheimer’s disease (AD). A unique feature of AD immunotherapies is that an immune response against a self-antigen needs to be elicited without causing adverse autoimmune reactions. Current research is focused on two possible targets in this regard. One is the inhibition of accumulation and deposition of amyloid beta 1–42 (Aβ42), which is one of the major peptides found in senile plaques, and the second target is hyperphosphorylated tau, which forms neurofibrillary tangles inside the nerve cell and shows association with the progression of dementia. Mouse models have shown that immunotherapy targeting Aβ42 as well as tau with the respective anti-Aβ or anti-tau antibodies can provide significant improvements in these mice. While anti-Aβ immunotherapy (active and passive immunizations) is already in several stages of clinical trials, tau-based immunizations have been analyzed only in mouse models. Recently, as a significant correlation of progression of dementia and levels of phosphorylated tau have been found, high interest has again focused on further development of tau-based therapies. While Aβ immunotherapy might delay the onset of AD, immunotherapy targeting tau might provide benefits in later stages of this disease. Last but not least, targeting Aβ and tau simultaneously with immunotherapy might provide additional therapeutic effects, as these two pathologies are likely synergistic; this is an approach that has not been tested yet. In this review, we will summarize animal models used to test possible therapies for AD, some of the facts about Aβ42 and tau biology, and present an overview on halted, ongoing, and upcoming clinical trials together with ongoing preclinical studies targeting tau or Aβ42.

Cost effectiveness of recruitment methods in an obesity prevention trial for young children

BACKGROUND

Recruitment of participants for clinical trials requires considerable effort and cost. There is no research on the cost effectiveness of recruitment methods for an obesity prevention trial of young children.

METHODS

This study determined the cost effectiveness of recruiting 70 families with a child aged 4 to 7 (5.9+/-1.3) years in Western New York from February 2003 to November 2004, for a 2-year randomized obesity prevention trial to reduce television watching in the home.

RESULTS

Of the 70 randomized families, 65.7% (n=46) were obtained through direct mailings, 24.3% (n=17) were acquired through newspaper advertisements, 7.1% (n=5) from other sources (e.g., word of mouth), and 2.9% (n=2) through posters and brochures. Costs of each recruitment method were computed by adding the cost of materials, staff time, and media expenses. Cost effectiveness (money spent per randomized participant) was US $0 for other sources, US $227.76 for direct mailing, US $546.95 for newspaper ads, and US $3,020.84 for posters and brochures.

CONCLUSION

Of the methods with associated costs, direct mailing was the most cost effective in recruiting families with young children, which supports the growing literature of the effectiveness of direct mailing.