Test 1 (EBVM 1-12) Flashcards
What is involved in a PICO?
patient, intervention, comparison, outcome
definition of EBVM
the conscientious and judicious use of the current best evidence in the health care of individuals and populations; integrating individual clinical expertise with the best available external clinical evidence from systematic research
what does EBVM help us do
helps determine which is the BEST approach for the CASE/SITUATION
three main steps of EBVM
-diagnostic process
-treatment alternatives
-disease prevention
what is included in the diagnostic process
diagnostic decisions such as tests and their performance
what is included in treatment alternatives
treatment decisions, interventions and strength of evidence associated with them
what is included in disease prevention
preventative health decisions, herd health and wellness, and causation
what are the 6 steps in the diagnostic process
- presenting complaint
- history
- general inspection
- routine physical exam
- clinical or other tests
- diagnosis!
four LDA treatment options
-right paramedian abomasopexy
-omentopexy
-bar suture (toggle pin) abomasopexy
-roll and treat medically
what are the two highest pieces of evidence
systematic reviews and meta-analysis
three types of observational studies
cross sectional, case control and cohort studies
two type sof experimental studies
experiements and clinical trials (RCTs)
both observational studies and experimental studies are ____ _____ studies
hypothesis testing
what two study types have temporal sequence established
RCTs and cohort studies
what two study types have unknown temporal relationships
cross sectional and case control
advantages of cohort studies (3)
-generally preferred over case control studies bc the are statistically more reliable
-compared to case-control they can establish the timing and sequence of events
-in prospective studies, data collection can be standardized, as opposed to retrospective studies which use historical records
disadvantages of cohort studies (4)
-blinding within the studies is difficult. identifying a matched control group to minimize other variables can also be difficult
-cohort studies arent as reliable as RCTs as the two groups of animals may differ in ways other than simply in respect of the variable under study
-can take a long time to complete and there might be a loss of participants
-not useful for rare diseases as it would be difficult to recruit sufficient patients
what happens in a cohort study
animals exposed to a causal factor are followed over time and compared with another group of animals which are not exposed to that factor.
what are results normally expressed as in a cohort study
risk ratio
can absolute risk be determined in a cohort study
yes
what happens in a case control study
animals which have developed a disease or condition are identified, and their exposure to suspected causal or risk factors is compared with that of a control group which do not have that disease/condition. information regarding exposure is historical
what are results normally expressed as in a case control study
odds ratios
can absolute risk be determined in a case control study
no
advantages of a case control study (4)
-quick to perform and dont require special methods to conduct
-generally inexpensive and may be the only way in which rare conditions or those with a protracted incubation period can realistically be studied
-can be used to evaluate interventions as well as associations
-useful for formulating hypotheses that can be tested using study designs higher up in the hierarchy such as cohorts and RCTs
disadvantages of a case control study (3)
-less reliable than RCTs or cohort studies as it is difficult to match the control group and eliminate confounding variables
-not possible to calculate true incidence/prevalence and relative risk
-data is collected retrospectively and elements may be missing or of poor quality
what happens in a RCT
study design of choice for answering questions about the effectiveness of different treatments. a search for evidence from studies of this design should be a priority when asking questions about therapies
advantages of RCT (3)
-random allocation of animals into study groups reduces the risk of bias and is the most powerful method of eliminating known and unknown confounding variables
-the RCT is the most powerful study design for data collection
-the study design increases the probability that the differences between the study groups can be attributed to the treatment
disadvantages of RCT (2)
-its sometimes not possible to allow for an untreated control group due to the severity of the effects of witholding an effective treatment
-expensive to conduct and relatively rare it vet med
what is “random”
same chance of getting A or B treatment. cant have a sequence
WHAT KIND OF STUDY IS THIS
Cows were blocked by parity and randomly assigned to receive an oral bolus of Ca (42 g of Ca) within 12 h
after calving and a second bolus 12 h later (TRT; n = 51), or no Ca
supplementation (CON; n = 49).
Concentrations in serum of total Ca (tCa), haptoglobin (Hp), and albumin (ALB) were assessed at d 0 (within
12 h postpartum), 0.5 (12 h later), 1, 2, 4, 6, and 8 postpartum; ionized calcium was assessed at d 0, 0.5, 2, and 4, and lipopolysaccharide binding protein (LBP) and serum amyloid A (SAA) were assessed at d 0, 2, and 4.
RCT
WHAT KIND OF STUDY IS THIS
The condition of 640 male dairy calves was recorded and their health deterioration, morbidity, and
mortality evaluated after long-distance transport. Assessments included a health examination, weight estimation, and measure of failed transfer of passive immunity (FTPI). A McNemar Test and logistic regression analysis were used to evaluate the effects of pre-transport condition on subsequent health.
cohort
WHAT KIND OF STUDY IS THIS
The objective of this study was to investigate the relationship between management practices and
antimicrobial use in heifer calves on Canadian dairy farms. Questionnaires on calf management practices, herd characteristics, and calf treatment records were administered on 147 dairy farms in 5 provinces during annual farm visits. Antimicrobial treatment records were collected on each farm from either an electronic herd management system or paper-based records.
cross sectional
WHAT KIND OF STUDY IS THIS
A study was performed to assess risk factors associated with feline ureteral obstruction (UO). Cases were defined as cats with either of the following: (1) ureteral obstruction (ureteroliths: 13/18; unknown: 5/18) confirmed with pyelography; or (2) a creatinine concentration >140 μmol/l with both UO (ureteroliths: 6/10; blood clots: 3/10; pyonephrosis: 1/10) and pyelectasia ⩾5 mm on abdominal ultra sonography. Controls were defined as cats without evidence of UO on history, physical examination and abdominal ultrasound. Age, sex,
breed (domestic shorthair/longhair), diet (predominantly dry, mixed or predominantly moist food), housing
(indoors or mixed) and plasma total calcium were evaluated for their association with UO using multivariable logistic regression.
case control
what are the 14 pieces of information/questions you need answered to be able to trust a study?
- Are you able to define the type of study?
- Clearly stated objectives | Relevance check
- External validity - extrapolation
- Inclusions and exclusions
- Group definition & allocation
- Procedures appropriately defined & applied
- Equal scrutiny of ALL groups (“blinding”)
- Outcomes defined & appropriate
- Biases / confounders dealt with
- Statistical Analysis – appropriate tools
- Statistical Analysis – proper interpretation (what’s a P value and 95% Confidence intervals)
- Sample Size determinations based on the outcome of interest
- Clear and Complete Results
- Conclusions appropriate and complete
three types of clinical questions
diagnostic, treatment, preventive
“What is the accuracy of rectal palpation for identifying functional
CL’s in dairy cows?”
what type of clinical question is this
diagnostic
“Is surgical repair superior to confinement & rest in resolving
lameness due to anterior cruciate rupture in large breed dogs?”
what type of clinical question is this
treatment
“How much reduction in morbidity should I expect in beef calves vaccinated with Triangle 9 at arrival in a large feedlot? “
what type of clinical question is this
preventive
“In canines with osteoarthritis does fish oil supplementation improve quality of life parameters?”
whats missing from this clinical question
Population: try to define your
population to reflect any characteristics that might influence
development of OA or response to
treatment. ex. age, comorbidities
Intervention-Comparison: you list fish
oil supplements, but there’ no
comparison Additionally, define your
treatment (dosage, route of administration, frequency, etc)
Outcome: how will you define quality of life? Find an objective measure to help make your clinical decision.
“Which surgical intervention (tibial-plateau-leveling osteotomy (TPLO) vs. lateral fabellar suture stabilization (LFSS) leads to a reduced osteoarthritis (OA) score in active, young dogs with cranial cruciate ligament rupture?”
whats missing from this clinical question
Outcome: osteoarthritis development is a relevant outcome, but defining a time frame would be more specific. Follow up period: Are we wanting to know if the dog develops OA in 3 months? 8 years?
Population: define a breed size, as things like weight/weight bearing
might impact your treatment decisions and outcome
In dogs experiencing dystocia and requiring a C-section, does performing a c-section as opposed to a csection spay affect the survival rate of the puppies?
whats missing from this clinical question
Other maternal factors that might play a role here? [age? Brachiocephalic phenotype? ]
You may wish to define the period of survival in the puppies. (immediate neonatal period, or further along?)
what are some sources of evidence in practice (5)
-Personal Experience
-Colleagues
-Textbooks, Reviews, CPD meetings
-Practice Records
-Journals (namely peer-reviewed papers)
what are some practice record issues (4)
-Quality
-Completeness
-Case definition
-Follow-up (outcomes & complications)
most practice records were not designed to do what?
evaluate outcomes of procedures
what are three things we need to consider if we are using practice records
-incidence/prevalence of a disease = need a case definition
-probability of success = need follow up and outcomes
-complications = need to be recorded
how do we define a new case? (4)
-distinct case? is this the 1st vs new vs recurrent
-who is at risk? (parity, DIM, etc)
-how long are they at risk?
-how do we define a cure (outcome)?
what are the biggest issues in practice around finding the answer?
access and ability to find the right articles
what are three databases for animal health
CAB direct, pubmed/medline, agricola
three types of descriptive papers
case report, case series, review papers
what is different between descriptive papers and explanatory papers
descriptive papers do not have controls or comparisons
features of descriptive papers (6)
-detailed descrption of uncommon diseases
-biased in case selection
-no controls or comparison group
-raise awareness
-generate great questions for future research
-not very useful for decision making
what do we mean by association vs causation
Just because a risk factor and an outcome occur together more commonly than one would expect by chance alone, doesn’t mean that the risk factor CAUSES the outcome!
hills criteria for causation (7)
– Temporal Relationship (Exposure → Outcome)
– Strength of Association (RR or OR)
– Dose-Response
– Biological Plausibility
– Consistency or Repetition
– Rule Out other potential causes
– Reversal
the more of the hills criteria you can include in your search = the stronger the ______ argument
causal
what is the best type of study for rare diseases
case control
what is the best type of study for rare risk factors
cohort
two measures of association
relative risk and odds ratio
what is a measure of association
-measure the magnitude/strength of the relationship between an exposure (E) and outcome (O) as a relative effect
-it is A RATIO of two estimates of disease frequency
what type of studies can be use risk ratio in
cross sectional or cohort studies
what type of studies can be use odds ratio in
all studies
what is the chi square test of independence used for
used to test whether two categorical variables are related to each other