Dataset Information

Standardizing vitamin D assays: the way forward.

ABSTRACT: For a number of years it has been widely assumed that measurement of serum 25-hydroxyvitamin D [25(OH)D] concentration is the best approach to assessing an individual's vitamin D status. However, it has also been recognized that there is substantial within-assay variation in 25(OH)D measurement and even greater between-assay variability. Such assay variation clearly confounds attempts to define what constitutes the diagnosis of hypovitaminosis D. Importantly, assay variability makes pooling of 25(OH)D results from different studies in systematic reviews for the specific purpose of determining dose-response and/or clinical cut points at best problematic. Therefore, to develop and implement evidence-based clinical guidelines, it is essential that 25(OH)D measurement be standardized in both clinical and research laboratories. In this Perspective we outline a way forward toward achieving this goal-the Vitamin D Standardization Program (VDSP).

SUBMITTER: Binkley N

PROVIDER: S-EPMC5443565 | biostudies-literature | 2014 Aug

REPOSITORIES: biostudies-literature

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Standardizing vitamin D assays: the way forward.

Binkley Neil N Sempos Christopher T CT

Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 20140801 8

For a number of years it has been widely assumed that measurement of serum 25-hydroxyvitamin D [25(OH)D] concentration is the best approach to assessing an individual's vitamin D status. However, it has also been recognized that there is substantial within-assay variation in 25(OH)D measurement and even greater between-assay variability. Such assay variation clearly confounds attempts to define what constitutes the diagnosis of hypovitaminosis D. Importantly, assay variability makes pooling of 2 ...[more]

PMID: 24737265

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Project description:BACKGROUND:With India preparing for the next decennial Census in 2021, we compared the disability estimates and data collection methodology between the Census 2011 and the most recent population-level survey for India and its states, to highlight the issues to be addressed to improve robustness of the disability estimates in the upcoming Census. METHODS:Data from the Census 2011 and from two complementary nationally representative household surveys that covered all Indian states with the same methodology and survey instruments-the District-Level Household Survey-4 (DLHS-4, 2012-2013) and the Annual Health Surveys (AHS three rounds, 2010-11, 2011-12 and 2012-13) were used. Data from DLHS-4 and AHS 2012-13 round were pooled to generate estimates for the year 2012-13. Data collection methodology between the sources was compared, including the review of definitions of each type of disability. The overall, mental, visual, hearing, speech, and movement disability rate (DR) per 100,000 population were compared between the sources for India and for each state, and the percent difference in the respective rates was calculated. We explored the reliability of these estimates comparing yearly data from the AHS for three successive rounds. RESULTS:Survey data were collected through proxy reporting, however, it is not entirely clear whether the data were proxy- or self-reported or a mix of both in the Census. The overall DR was 25.1% higher in the Census (2,242; 95% CI 2,241-2,243) than the survey (1,791; 95% CI 1,786-1,797) per 100,000 population, with the state-level difference ranging from -64% in Tamil Nadu to 107% in Sikkim state. Despite both sources using nearly similar definitions for overall disability and disability by type, the difference in DR was 125.5%, 54.2%, -25.7%, -19.7%, and 21.9% for hearing, speech, mental, movement, and visual DR, respectively. At the state-level, the difference in disability-specific estimates ranged from -84% to 450%. The extent of variations in the disability-specific estimates in AHS successive rounds ranged from -25% to 929% at the state-level. CONCLUSIONS:There is momentum globally towards building disability measurement that is consistent with the data required for monitoring of the Sustainable Development Goals to ensure robust estimation of disability. The current estimates from the Census and surveys seem much lower than would be expected at the population level. We make recommendations that India needs to take serious note of in order to improve the validity and reliability of India's disability estimates.

Dataset Information

Standardizing vitamin D assays: the way forward.

Publications

Standardizing vitamin D assays: the way forward.

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