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ABSTRACT: Studies examining the relationship between total circulating 25-hydroxyvitamin D [25(OH)D] levels and bone mineral density (BMD) have yielded mixed results. Vitamin D-binding protein (DBP), the major carrier protein for 25(OH)D, may alter the biologic activity of circulating vitamin D. We hypothesized that free and bioavailable 25(OH)D, calculated from total 25(OH)D, DBP, and serum albumin levels, would be more strongly associated with BMD than levels of total 25(OH)D. We measured total 25(OH)D, DBP, and serum albumin levels in 49 healthy young adults enrolled in the Metabolic Abnormalities in College-Aged Students (MACS) study. Lumbar spine BMD was measured in all subjects using dual-energy X-ray absorptiometry. Clinical, diet, and laboratory information also was gathered at this time. We determined free and bioavailable (free + albumin-bound) 25(OH)D using previously validated formulas and examined their associations with BMD. BMD was not associated with total 25(OH)D levels (r = 0.172, p = .236). In contrast, free and bioavailable 25(OH)D levels were positively correlated with BMD (r = 0.413, p = .003 for free, r = 0.441, p = .002 for bioavailable). Bioavailable 25(OH)D levels remained independently associated with BMD in multivariate regression models adjusting for age, sex, body mass index, and race (p = .03). It is concluded that free and bioavailable 25(OH)D are more strongly correlated with BMD than total 25(OH)D. These findings have important implications for vitamin D supplementation in vitamin D-deficient states. Future studies should continue to explore the relationship between free and bioavailable 25(OH)D and health outcomes.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 03/2011; 26(7):1609-16. · 6.04 Impact Factor
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The Journal of allergy and clinical immunology 02/2011; 127(5):1302-4.e1. · 9.17 Impact Factor
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ABSTRACT: To compare the demographic and geographic patterns of pneumonia and influenza (P&I) hospitalizations in older adults with dementia with those of the U.S. population and to examine the relationship between healthcare accessibility and P&I.
Observational study using historical medical claims from the Centers for Medicare and Medicaid Services (CMS) and CMS records supplemented with information derived from other large national sources.
Retrospective analysis of medical records uniformly collected over a 5-year period with comprehensive national coverage.
A study population representative of more than 95% of all people aged 65 and older residing in the continental United States.
Six million two hundred seventy-seven thousand six hundred eighty-four records of P&I between 1998 and 2002 were abstracted, and county-specific outcomes for hospitalization rates of P&I, mean length of hospital stay, and percentage of deaths occurring in a hospital setting were estimated. Associations with county-specific elderly population density, percentage of nursing home residents, median household income per capita, and rurality index were assessed.
Rural and poor counties had the highest rate of P&I and percentage of influenza. Patients with dementia had a lower frequency of influenza diagnosis, a shorter length of hospital stay, and 1.5 times as high a rate of death as the national average.
The results suggest strong disparities in healthcare practices in rural locations and vulnerable populations; infrastructure, proximity, and access to healthcare are significant predictors of influenza morbidity and mortality. These findings have important implications for influenza vaccination, testing, and treatment policies and practices targeting the growing fraction of patients with cognitive impairment.
Journal of the American Geriatrics Society 10/2009; 57(12):2192-9. · 3.74 Impact Factor
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ABSTRACT: Although it is widely acknowledged that protocol design plays a crucial role in the success of clinical research studies, how protocols have changed over time and the impact of these changes on clinical trial performance have never been quantified. To measure protocol design trends, the Tufts Center for the Study of Drug Development analyzed data on 10,038 unique phase 1-4 protocols conducted between 1999 and 2005. Tufts Center for the Study of Drug Development analyzed study conduct performance data on 57 individual phase 2 and 3 protocols administered at US-based investigative sites. The results of this study indicate that the number of unique procedures and the frequency of procedures per protocol have increased at the annual rate of 6.5% and 8.7%, respectively, during the time period measured. Investigative site work burden to administer each protocol increased at an even faster rate of 10.5% between 1999 and 2005. Additionally, during this time period, study conduct performance--that is, cycle time and patient recruitment and retention rates--worsened; and the number of protocol amendments, observed serious adverse events, and length of case report forms increased substantially. Implications of these results for simplifying protocol designs and minimizing negative effects on study conduct performance are discussed.
American journal of therapeutics 15(5):450-7.
