David Kendrick

Bio: David Kendrick is an academic researcher from Brigham and Women's Hospital. The author has contributed to research in topics: Health care & Diabetes management. The author has an hindex of 5, co-authored 7 publications receiving 563 citations. Previous affiliations of David Kendrick include Partners HealthCare & Harvard University.

Efficacy of Antiretroviral Therapy Programs in Resource-Poor Settings: A Meta-analysis of the Published Literature

Abstract: Despite the advent of effective combination antiretroviral drug therapy (ART) for the treatment of human immunodeficiency virus (HIV) infection many doubt the feasibility of ART treatment programs in resource-poor settings. We performed a meta-analysis of the efficacy of ART programs in the developing world. We searched the Medline database with the index terms “HIV” “antiretroviral therapy” “CD4 count” “viral load” “experience” and “outcomes.” A total of 201 abstracts were reviewed and 25 articles were selected for detailed review. Ten observational studies with details on patient outcomes were ultimately included in the analysis. Three readers independently extracted data from the articles. The details recorded included patient demographic characteristics baseline CD4 cell counts baseline HIV RNA viral loads ART histories outcomes and timing of the outcome measure. The proportion of subjects with an undetectable HIV viral load provided the measure of treatment efficacy. A random-effects model weighted the proportion of patients with undetectable viral load at various time points during ART. The proportion was 0.697 (95% CI 0.582–0.812) at month 6 and 0.573 (95% CI 0.432– 0.715) at month 12 of ART. The provision of medications free of charge to the patient was associated with a 29%– 31% higher probability of having an undetectable viral load at months 6 and 12 than was the requirement that patients pay part or all of the cost of therapy. ART treatment programs in resource-poor settings have efficacy rates similar to those reported for developed countries. The provision of medications free of charge to the patient is associated with a significantly increased probability of virologic suppression at months 6 and 12 of ART. (authors)

Numerical experiments with model monophyletic and paraphyletic taxa

Abstract: The problem of how accurately paraphyletic taxa versus monophyletic (i.e., holophyletic) groups (clades) capture underlying species patterns of diversity and extinction is explored with Monte Carlo simulations. Phylogenies are modeled as stochastic trees. Paraphyletic taxa are defined in an arbitrary manner by randomly choosing progenitors and clustering all descendants not belonging to other taxa. These taxa are then examined to determine which are clades, and the remaining paraphyletic groups are dissected to discover monophyletic subgroups. Comparisons of diversity patterns and extinction rates between modeled taxa and lineages indicate that paraphyletic groups can adequately capture lineage information under a variety of conditions of diversification and mass extinction. This suggests that these groups constitute more than mere "taxonomic noise" in this context. But, strictly monophyletic groups perform somewhat better, especially with regard to mass extinctions. However, when low levels of paleontologic sampling are simulated, the veracity of clades deteriorates, especially with respect to diversity, and modeled paraphyletic taxa often capture more information about underlying lineages. Thus, for studies of diversity and taxic evolution in the fossil record, traditional paleontologic genera and families need not be rejected in favor of cladistically-defined taxa.

Benefits of Information Technology–Enabled Diabetes Management

Abstract: Objective: To determine the financial and clinical benefits of implementing information technology enabled disease management systems. Research Design and Methods: A computer model was created to project the impact of information technology enabled disease management on care processes, clinical outcomes and medical costs for patients with type 2 diabetes over the age of 25 in the United States. Several information technologies were modeled: diabetes registries, computerized decision support, remote monitoring, patient self-management systems and payer based systems. Estimates of care process improvements were derived from published literature. Simulations projected outcomes for both payer and provider organizations, scaled to the national level. The primary outcome was medical cost savings, in 2004 U.S. dollars discounted at 5%. Secondary measures include reduction of cardiovascular, cerebrovascular, neuropathy, nephropathy and retinopathy clinical outcomes. Results: All forms of information technology enabled disease management improved the health of patients with diabetes and reduced health care expenditures. Over ten years, diabetic registries saved $14.5 billion, computerized decision support saved $10.7 billion, payer-centered technologies saved $7.10 billion, remote monitoring saved $326 million, self-management saved $285 million, and integrated provider-patient systems saved $16.9 billion. Conclusions: Information technology enabled diabetes management has the potential to improve care processes, delay diabetic complications and save healthcare dollars. Of existing systems, provider-centered technologies such as diabetes registries currently show the most potential for benefit. Fully integrated provider-patient systems would have even greater potential for benefit. These benefits must be weighed against the implementation costs.

The cost of information technology-enabled diabetes management.

Abstract: As a result of the high cost of diabetes, an array of interventions for managing this disease has been developed. Estimating the cost of various approaches to diabetes disease management is critical to inform purchasing decisions. This review focuses on 5 provider- and payer-sponsored diabetes management approaches that use information technology (IT) and provides cost estimates for each approach based on a literature review and interviews with 38 provider practices, hospitals, payers, and vendors. Cost estimates are reported for "typical" small, medium, and large provider practices and payers. Provider-sponsored diabetes registries are estimated to be the least expensive approach for small and medium sized practices. For large practices with electronic health record systems, modifying such systems with diabetes-specific clinical decision support capabilities is projected to be the most economical approach. While limited data prevented the inclusion of all implementation costs, these projections serve as a starting point to inform the purchasing decisions of organizations planning to introduce IT-enabled diabetes management.

Patient Retention in Antiretroviral Therapy Programs in Sub-Saharan Africa: A Systematic Review

Abstract: Background Long-term retention of patients in Africa’s rapidly expanding antiretroviral therapy (ART) programs for HIV/AIDS is essential for these programs’ success but has received relatively little attention. In this paper we present a systematic review of patient retention in ART programs in sub-Saharan Africa. Methods and Findings We searched Medline, other literature databases, conference abstracts, publications archives, and the ‘‘gray literature’’ (project reports available online) between 2000 and 2007 for reports on the proportion of adult patients retained (i.e., remaining in care and on ART) after 6 mo or longer in sub-Saharan African, non-research ART programs, with and without donor support. Estimated retention rates at 6, 12, and 24 mo were calculated and plotted for each program. Retention was also estimated using Kaplan-Meier curves. In sensitivity analyses we considered best-case, worst-case, and midpoint scenarios for retention at 2 y; the best-case scenario assumed no further attrition beyond that reported, while the worst-case scenario assumed that attrition would continue in a linear fashion. We reviewed 32 publications reporting on 33 patient cohorts (74,192 patients, 13 countries). For all studies, the weighted average follow-up period reported was 9.9 mo, after which 77.5% of patients were retained. Loss to follow-up and death accounted for 56% and 40% of attrition, respectively. Weighted mean retention rates as reported were 79.1%, 75.0% and 61.6 % at 6, 12, and 24 mo, respectively. Of those reporting 24 mo of follow-up, the best program retained 85% of patients and the worst retained 46%. Attrition was higher in studies with shorter reporting periods, leading to monthly weighted mean attrition rates of 3.3%/mo, 1.9%/mo, and 1.6%/month for studies reporting to 6, 12, and 24 months, respectively, and suggesting that overall patient retention may be overestimated in the published reports. In sensitivity analyses, estimated retention rates ranged from 24% in the worse case to 77% in the best case at the end of 2 y, with a plausible midpoint scenario of 50%.

Early mortality among adults accessing antiretroviral treatment programmes in sub-Saharan Africa.

Abstract: Two-thirds of the world's HIV-infected people live in sub-Saharan Africa, and more than 1.5 million of them die annually. As access to antiretroviral treatment has expanded within the region; early pessimism concerning the delivery of antiretroviral treatment using a large-scale public health approach has, at least in the short term, proved to be broadly unfounded. Immunological and virological responses to ART are similar to responses in patients treated in high-income countries. Despite this, however, early mortality rates in sub-Saharan Africa are very high; between 8 and 26% of patients die in the first year of antiretroviral treatment, with most deaths occurring in the first few months. Patients typically access antiretroviral treatment with advanced symptomatic disease, and mortality is strongly associated with baseline CD4 cell count less than 50 cells/mul and WHO stage 4 disease (AIDS). Although data are limited, leading causes of death appear to be tuberculosis, acute sepsis, cryptococcal meningitis, malignancy and wasting syndrome. Mortality rates are likely to depend not only on the care delivered by antiretroviral treatment programmes, but more fundamentally on how advanced disease is at programme enrollment and the quality of preceding healthcare. In addition to improving delivery of antiretroviral treatment and providing it free of charge to the patient, strategies to reduce mortality must include earlier diagnosis of HIV infection, strengthening of longitudinal HIV care and timely initiation of antiretroviral treatment. Health systems delays in antiretroviral treatment initiation must be minimized, especially in patients who present with advanced immunodeficiency.

Diversification and extinction in the history of life

Abstract: Analysis of the fossil record of microbes, algae, fungi, protists, plants, and animals shows that the diversity of both marine and continental life increased exponentially since the end of the Precambrian. This diversification was interrupted by mass extinctions, the largest of which occurred in the Early Cambrian, Late Ordovician, Late Devonian, Late Permian, Early Triassic, Late Triassic, and end-Cretaceous. Most of these extinctions were experienced by both marine and continental organisms. As for the periodicity of mass extinctions, no support was found: Seven mass extinction peaks in the last 250 million years are spaced 20 to 60 million years apart.

Insect diversity in the fossil record

Abstract: Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate groups. The great radiation of modern insects began 245 million years ago and was not accelerated by the expansion of angiosperms during the Cretaceous period. The basic trophic machinery of insects was in place nearly 100 million years before angiosperms appeared in the fossil record.