83 research outputs found
A framework for measurement and harmonization of pediatric multiple sclerosis etiologic research studies: The Pediatric MS Tool-Kit
Background: While studying the etiology of multiple sclerosis (MS) in children has several methodological advantages over studying etiology in adults, studies are limited by small sample sizes.
Objective: Using a rigorous methodological process, we developed the Pediatric MS Tool-Kit, a measurement framework that includes a minimal set of core variables to assess etiological risk factors.
Methods: We solicited input from the International Pediatric MS Study Group to select three risk factors: environmental tobacco smoke (ETS) exposure, sun exposure, and vitamin D intake. To develop the
Tool-Kit, we used a Delphi study involving a working group of epidemiologists, neurologists, and content
experts from North America and Europe.
Results: The Tool-Kit includes six core variables to measure ETS, six to measure sun exposure, and six
to measure vitamin D intake. The Tool-Kit can be accessed online (www.maelstrom-research.org/mica/
network/tool-kit).
Conclusion: The goals of the Tool-Kit are to enhance exposure measurement in newly designed pediatric
MS studies and comparability of results across studies, and in the longer term to facilitate harmonization
of studies, a methodological approach that can be used to circumvent issues of small sample sizes. We
believe the Tool-Kit will prove to be a valuable resource to guide pediatric MS researchers in developing
study-specific questionnaire
Measurement error adjustment in essential fatty acid intake from a food frequency questionnaire: alternative approaches and methods
<p>Abstract</p> <p>Background</p> <p>We aimed at assessing the degree of measurement error in essential fatty acid intakes from a food frequency questionnaire and the impact of correcting for such an error on precision and bias of odds ratios in logistic models. To assess these impacts, and for illustrative purposes, alternative approaches and methods were used with the binary outcome of cognitive decline in verbal fluency.</p> <p>Methods</p> <p>Using the Atherosclerosis Risk in Communities (ARIC) study, we conducted a sensitivity analysis. The error-prone exposure â visit 1 fatty acid intake (1987â89) â was available for 7,814 subjects 50 years or older at baseline with complete data on cognitive decline between visits 2 (1990â92) and 4 (1996â98). Our binary outcome of interest was clinically significant decline in verbal fluency. Point estimates and 95% confidence intervals were compared between naĂŻve and measurement-error adjusted odds ratios of decline with every SD increase in fatty acid intake as % of energy. Two approaches were explored for adjustment: (A) External validation against biomarkers (plasma fatty acids in cholesteryl esters and phospholipids) and (B) Internal repeat measurements at visits 2 and 3. The main difference between the two is that Approach B makes a stronger assumption regarding lack of error correlations in the structural model. Additionally, we compared results from regression calibration (RCAL) to those from simulation extrapolation (SIMEX). Finally, using structural equations modeling, we estimated attenuation factors associated with each dietary exposure to assess degree of measurement error in a bivariate scenario for regression calibration of logistic regression model.</p> <p>Results and conclusion</p> <p>Attenuation factors for Approach A were smaller than B, suggesting a larger amount of measurement error in the dietary exposure. Replicate measures (Approach B) unlike concentration biomarkers (Approach A) may lead to imprecise odds ratios due to larger standard errors. Using SIMEX rather than RCAL models tends to preserve precision of odds ratios. We found in many cases that bias in naĂŻve odds ratios was towards the null. RCAL tended to correct for a larger amount of effect bias than SIMEX, particularly for Approach A.</p
The risk of lung cancer related to dietary intake of flavonoids
It has been hypothesized that flavonoids in foods and beverages may reduce cancer risk through
antioxidation, inhibition of inflammation, and other antimutagenic and antiproliferative
properties. We examined associations between intake of five flavonoid subclasses
(anthocyanidins, flavan-3-ols, flavones, flavonols, flavanones) and lung cancer risk in a
population-based case-control study in Montreal, Canada (1,061 cases and 1,425 controls).
Flavonoid intake was estimated from a food frequency questionnaire that assessed diet two years
prior to diagnosis (cases) or interview (controls). Odds ratios (ORs) and 95% confidence
intervals (CIs) were estimated using unconditional logistic regression. Overall, total flavonoid
intake was not associated with lung cancer risk, the effect being similar regardless of sex and
smoking level. However, low flavonoid intake from food, but not from beverages, was
associated with an increased risk. The adjusted ORs (95% CIs) comparing the highest versus the
lowest quartiles of intake were 0.63 (0.47-0.85) for total flavonoids, 0.82 (0.61-1.11) for
anthocyanidins, 0.67 (0.50-0.90) for flavan-3-ols, 0.68 (0.50-0.93) for flavones, 0.62 (0.45-0.84)
for flavonols, and 0.70 (0.53-0.94) for flavanones. An inverse association with total flavone and
flavanone intake was observed for squamous cell carcinoma but not adenocarcinoma. In
conclusion, low flavonoid intake from food may increase lung cancer risk
Geodemographic Patterns of Meat Expenditure in Great Britain
The future of the meat industry will require the management of important trade-offs between economic, environmental and health aspects of both humans and animals. Understanding the patterns and trends of meat expenditure and consumption is crucial for assessing the current resilience of the system and for economic, planning, health and environmental applications. Here, we show how the technique of geodemographic classification, combined with fine scale expenditure estimates can be used to explore temporal and spatial patterns of meat expenditure in Great Britain between 2008 and 2017. Whilst the expenditure patterns of some food categories such as sausages remained relatively consistent, others such as lamb show a trend towards a reduced proportion of expenditure and increased inequality of purchases. Short term changes in expenditure patterns also occurred, potentially due to product specific price variability, price elasticities or zoonotic disease scare. Environmental attitudes, financial constraints and the prominence of communities who do not eat meat for religious or cultural reasons are likely to be driving the differences between geodemographic groups. The methodology and results could be a valuable tool for policy makers in the meat industry and beyond
Effect of a medical food on body mass index and activities of daily living in patients with Alzheimer's disease: secondary analyses from a randomized, controlled trial
Contains fulltext :
97852.pdf (publisher's version ) (Closed access)OBJECTIVES: To investigate the effect of a medical food (Souvenaid) on body mass index (BMI) and functional abilities in patients with mild Alzheimer's disease (AD). DESIGN/SETTING/PARTICIPANTS/INTERVENTION /MEASUREMENTS: These analyses were performed on data from a 12-week, double-blind, randomized, controlled, multicenter, proof-of-concept study with a similarly designed and exploratory 12-week extension period. Patients with mild AD (Mini-Mental State Examination score of 20-26) were randomized to receive either the active product or an iso-caloric control product. While primary outcomes included measures of cognition, the 23-item Alzheimer's Disease Cooperative Study-Activities of Daily Living (ADCS-ADL) scale was included as a secondary outcome. Both ADCS-ADL and BMI were assessed at baseline and Weeks 6, 12 and 24. Data were analyzed using a repeated-measures mixed model. RESULTS: Overall, data suggested an increased BMI in the active versus the control group at Week 24 (ITT: p = 0.07; PP: p = 0.03), but no treatment effect on ADCS-ADL was observed. However, baseline BMI was found to be a significant treatment effect modifier (ITT: p = 0.04; PP: p = 0.05), and an increase in ADCS-ADL was observed at Week 12 in patients with a 'low' baseline BMI (ITT: p = 0.02; PP: p = 0.04). CONCLUSIONS: These data indicate that baseline BMI significantly impacts the effect of Souvenaid on functional abilities. In addition, there was a suggestion that Souvenaid increased BMI
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