Nutrition week 6 part 1

winniesmith2's version from 2017-11-09 15:15

Section 1

Question Answer
What is biasdefined as systematic error, resulting in over- or underestimation of the strength of an association between an exposure and an outcome e.g. sampling bias. If the association between a factor and a disease is not causal efforts to modify exposure to that factor will not reduce disease risk e.g. alcohol and lung cancer.
what is exposure the factor or set of factors that is responsible for the outcome being investigated. Cannot be measured directly
dietary exposure measurable at 4 points; National knowledge of production, import, export, storage called Food Balance (food disappearance) data published by FAO annually. Nutrient content from composition tables, exposure per person from population census
dietary exposure measurable at 4 points; household household budget surveys (HBS) provide expenditure (per week, month…) on food, food acquisitions (bought, grown, gifted, etc.). Also inventory, daily record of consumption, recall of purchases in previous week, month, etc. Problem of food eaten outside the home, snacks, etc. and individual consumption/distribution inside the home
dietary exposure measurable at 4 points; institutional catering records of acquisition and total food available or served per person. Problems of additional food available (snacks, etc.) and actual consumption
dietary exposure measurable at 4 points; individual prospective – food diaries, checklist, etc. and retrospective – FFQ, 24 hr recall, etc.
evidence; biomarkers nutrient or nutrient breakdown levels from body tissues (adipose, finger/to nails), fluids (urine, blood, saliva, etc.) and excreta. Problems of collection and variability of the timing of digestion, absorption, and usage/tissue deposition
evidence; anthropometry whole body or macro tissue cumulative responses to exposure to diet (energy) and toxins. Height, weight, BMI, etc. assessed against references/standards
outcome; morbidityconfirmed diagnosis of specific disease e.g. specific grade of malnutrition, marasmus, kwashiorkor, etc.
outcome; risk factors for future morbiditye.g. for NCD such as BP, BMI, Cholesterol, Lipids, ECG, etc.
outcome; mortality cause of death (accuracy), underlying, contributing, actual causes. Crude death rate (= total deaths/population) susceptible to error because of age profile of population - more older people more deaths – age-specific death rates or standardised mortality rates/ratios (mortality rates in given area v mortality rates in all areas e.g. Leicestershire v England)
types of bias; selection biascharacteristics of participants; how they were selected e.g. meat and cancer in the UK might be age related therefore broad age range in sample.
types of bias; measurement bias(Information bias); errors in assessment of exposure and/or outcome e.g. meat consumption weekdays v weekend days, accuracy, quantity, complete consumption, etc.
types of bias; confounding bias ; 3rd factor (confounder) explains the relationship e.g. alcohol and lung cancer
Prevalence rate The proportion of people within a population who have a particular disease e.g. the number of affected people for a given population size over a specified time period (e.g. per year).
Incidence rate The risk of developing a disease within an given measure of time e.g. the number of new cases of cancer per year

Section 2

Question Answer
Relative risk (RR)Ratio of the probability of an event occurring in an exposed group to the probability of the event occurring in a control (non-exposed) group
Odds ratio (OR)ratio of the odds of an event occurring in an exposed group to the odds of the event occurring in a control (non-exposed) group
hazard ratio (HR)rates of occurrence over time in the exposed and control groups
RR, OR and HR are indicators of the risk of an event (e.g. disease) occurring in one group compared to another
Probability a measure of how likely an event is = Number of adverse outcomes/total number of outcomes. Range 0 - 1. OR probability of an event is the number of ways that an event can occur divided by the total number of possible outcomes.
Oddsa measure of how likely an event is = Probability of an event/1 – probability of an event. OR The odds for an event is the ratio of the number of ways the event can occur to the number of ways it does not occur
use examples/ practice thiscalculating RR and OR - understand difference.
study designs in nutritional epidemiology -Ecological (correlational) study -Cross-sectional study -Case-control study -Cohort study (longitudinal) -Randomized control trial (RCT) -Systematic review and/or meta-analysis. -Experimental studies (clinical, community).88hj yu