Epidemiology Exam

In PubMed, combining two search terms with the connector 'OR' will retrieve a set that is __________ than the results would be for either term separately.

larger

investigator does not intervene; rather "observes" and assesses strength of the relationship between an exposure and outcome. a. experimental study b. observational study (descriptive, analytical)

observational studies

Study design where researcher "observes" exposure

observational study design.

broad term for disease, state of health, health-related event or death. Some studies may have multiple of these.

outcome

A ___________ is a document that details the conduct of a research study and includes the operational details of the study. It describes the background, rationale, objectives, design, methodology, statistical evaluation of the data, and organization of the project. Development of this is which step of conducting an RCT?

protocol = fill-in. Develop protocol = step 1 to conduct RCT. [RCT]

methods of randomization?

random numbers table, computerized randomization scheme. [RCT]

Each participant has the same chance of receiving each possible treatment. How is this possible?

randomization. [RCT]

History of Evidence Based Dentistry - Four Periods of EBM

1. Ancient period - authority, apprenticeship, experience anecdotal evidence. 2. Age of Enlightenment ~ 1700 - Scepticism about authorities (ancient and modern), Some formal evidence (clinical trials). 3. Transitional period ~ 1900 - concept of "end result", randomized controlled trials. 4. Modern period ~ 2000 - computers and databased software, culture of evaluative science ubiquitous and of vital importance

Epidemiology - Uses (4)

1. Assessing the community's health. 2. Making individual decisions. 3. Completing the clinical picture. 4. Searching for causes

Steps to conduct a RCT

1. Develop protocol 2. Institutional Review Board (IRB)/Ethics Committee Approval 4. Recruit participants 5. Consent/enroll participants 5. Randomization and blinding 6. Follow up for period of time 7. Analyze results [RCT]

Epidemiology - Core Functions (6)

1. Public health surveillance 2. Field investigation 3. Analytic studies 4. Evaluation 5. Linkages 6. Policy development

___________in epidemiology defines a set of people followed over a period of time. A group of people with defined characteristics. Are followed up to determine ___________ of some specific disease or outcome.

Cohort Studies: "Cohort" in epidemiology defines a set of people followed over a period of time. A group of people with defined characteristics. Are followed up to determine INCIDENCE (rate) of some specific disease or outcome.

What type of study is described here? Define selected group of subjects by exposure status at the start of the investigation. Both the exposed and unexposed groups must be selected from the SAME source population

Cohort studies

What is the highest-level of evidence on the evidence hierarchy?

Combining several selected RCT results in the highest-level of evidence on the evidence hierarchy. (aka Meta Analysis of several RCT's to get 1 avg/common conclusion of greater statistical power).

Inability to determine temporal relationship between risk factors and disease onset is a major weakness of what kind of study? Also, this study can assess _____________. [imp]

Cross-Sectional Studies - Strengths: - short, quick study time frame. - may get god response rate. - can look at specific population of interest. - *can assess PREVALENCE* Weaknesses: - ppl may choose not to participate, leading to potential bias. - not for rare or short lasting diseases. - can NOT determine temporal relationship btwn risk factors and disease onset (which came first?)

1. A method for combining pertinent study data from several selected studies to develop a single conclusion that has a greater statistical power is known as: A. Randomized Controlled Trial B. Cohort study C. Blinding D. Meta-analysis

D

1. Which odds ratio has the largest strength of association? A. 1.00 B. 1.50 C. 1.75 D. 3.00 [study questions]

D

4. Which procedure involves the concealment of group allocation from one or more individuals involved in randomized controlled trials? A. Systematic review B. Outcome C. Meta-Analysis D. Blinding [study questions]

D

7. Which of the following statements about confidence intervals is/are TRUE? A. Ideally, we want a confidence interval to have a high level of confidence AND be long B. Every 95% confidence interval goes "plus or minus" exactly 5%, and every 99% confidence interval goes "plus or minus" exactly 1% C. Both of the above D. Neither of the above [study questions]

D

True or False: Cohort studies are retrospective, meaning they go back in time to assess exposure.

False! C*o*hort studies are PR*O*SPECTIVE = - carried out from the present time into the future / go forward in time to assess outcome status. [*case*-control are *retro*spective]

Study Design - Levels of Evidence (WB memorize)

Highest to Lowest on pyramid: 1. Systematic Reviews and Meta Analysis 2. Randomized Controlled Double Blind Studies 3. Cohort studies 4. Case control studies 5. Case series 6. case reports 7. ideas, editorials, opinions. 8. animal research 9. in vitro ('test tube') research.

Eligibility Criteria [RCT]

Inclusion/exclusion criteria. Must fulfill characteristics needed for the study population. Profile of participants helps determine to whom the results can be generalized (women, minorities, less healthy people). [RCT]

What type of study is described here? A method for combining pertinent study data from several selected studies to develop a single conclusion that has greater statistical power. Analyzes information or data from a number of different studies to determine an average/common effect. Aimed to improve precision of the available data by looking at a greater number of people, including from different populations. Combining several selected RCT results in the highest-level of evidence on the evidence hierarchy.

Meta-Analysis

In PubMed, combining two search terms with the connector ______ is useful when combining all terms about the same concept.

OR

In PubMed, combining two search terms with the connector ________ will retrieve a set that is larger than the results would be for either term separately.

OR

Study design where researcher "observes" exposure and comparison IS made.

Observational (researcher observes exposure) *Analytical* (w. comparison) Study Design = 1. Cross-sectional [note: this falls under both analytical and descriptive] 2. Case-Control 3. Cohort

Study design where researcher "observes" exposure and NO comparison is made.

Observational (researcher observes exposure) *Descriptive* (no comparison) Study Design = 1. case report/case series 2. cross-sectional (e.g. survey) 3. ecological

What type of study is described here? Measured at one point in time for a population, "snapshot". Estimate prevalence. Exposure and outcome (disease) assessed at same time at single point in time! Can be used to monitor health status of a population.

Observational *Analytic*: Cross Sectional Studies.

Which type of study is described here? Compares groups but researcher has no control over assignment. There are instances where RCT cannot be done due to ethical reasons, and therefore _________ study is the best option (e.g., smoking and lung disease). a. Observational b. Experimental

Observational Analytic Studies. Fill in = observational.

What type of study is described here? Measured at one point in time for a population, "snapshot". Survey!

Observational Descriptive: Cross Sectional Studies.

2. Write a PICO for this research question: In patients with lesions that need to be "watched", will chewing xylitol-containing gum once a day decrease the likelihood of the "watched" lesion becoming a carious lesion? [study questions]

P: Patients with watched lesions. I: xylitol gum. C: n/a. O: reduced carious lesions. Explanation: Remember that you do not always need to include a C, particularly if you are comparing doing something to doing nothin

What type of study is described here? Provides a comprehensive review of all relevant studies on a particular clinical or health-related topic/question. All relevant studies are identified and those of adequate quality selected.

Systematic Reviews

Resource for Systematic Reviews in health care?

Cochrane Database (Includes Cochrane Reviews (the systematic reviews) and protocols for Cochrane Reviews as well as editorials).

True or False: Descriptive Studies can measure association and causality.

False - Can measure association, NOT causality.

(1) Which type of study identify subjects by OUTCOME of disease status at the START of study? (2) In this type of study, outcome status is identified and subjects are categorized as __________. (2) True or False: inclusion and exclusion criteria must be defined by investigator at any point during this type of study. (3) _______ are selected; subjects without the outcome but from the same source population; distribution of exposure should be the same among ______________. (4) Data about _______ to a risk factor or several risk factors are then collected. (5) At start of study, disease or outcome of interest has already occurred. The goal is to retrospectively determine the exposure to the risk factor from each of the two groups (cases and controls). (6) No intervention is attempted and no attempt is made to alter the course of the disease.

(1) Case-control studies: (2) outcome status is identified and subjects are categorized as CASES. (3) False - Investigator must define inclusion and exclusion criteria prior to the selection of cases. (3) CONTROLS are selected; subjects without the outcome but from the same source population; distribution of exposure should be the same among cases and controls (4) Data about EXPOSURE to a risk factor or several risk factors are then collected. (5) Retrospective (6) Observational

(1) What is the federally mandated organization of scientific and non-scientific persons, whose charge is to review research studies involving human subjects to ensure subject safety and welfare. ? (2) Fill in: While responsibility for the conduct of a research study ultimately lies with the _____________, an _______ goal is to ensure that any research study under its jurisdiction is in compliance with federal, state, and institutional regulations.

(1) Institutional Review Board (IRB) (2) While responsibility for the conduct of a research study ultimately lies with the Principal Investigator, an IRB's goal is to ensure that any research study under its jurisdiction is in compliance with federal, state, and institutional regulations. [step 2 for developing *RCT* is to be approved by IRB]. [RCT]

Data Analysis 1) When should statistical analysis methods be planned? 2) Appropriate analysis should be done when? [RCT]

1) Statistical analysis methods should be planned before the start of study procedures. 2) Appropriate analysis should be done at pre-determined time points (e.g., interim analysis, final analysis)

Read the following and answer questions 2-5 below. In a study assessing the association between body mass index and periodontitis, subjects' periodontal status was examined by one of three trained dentists. Eight designated molars and 2 incisors were probed. At least six points around each tooth and in total more than 60 points were probed for each subject. Subjects having at least one tooth with a periodontal pocket equal to or greater than 4 mm deep were defined as having periodontitis. For questions 2-5 below, suppose that the definition for periodontitis was then changed to having at least one tooth with a periodontal pocket equal to or greater than 3 mm deep. 1. How does this change in diagnostic criteria affect the sensitivity of diagnosing periodontitis? A. Sensitivity increases B. Sensitivity decreases C. No change 2. How does this change in diagnostic criteria affect the specificity of diagnosing severe periodontal disease? A. Specificity increases B. Specificity decreases C. No change 3. How would this change in diagnostic criteria affect the rate of false positives? A. False positive rate increases B. False positive rate decrease C. No change 4. How would this change in diagnostic criteria affect the rate of false negatives? A. False negative rate increases B. False negative rate decreases C. No change

1. A 2. B 3. A 4. B (lowering threshold => inc. sensitivity, dec. specificity => less false negatives and more false positives)

Read the following abstract and answer the next three questions associated with it: França IL, Sallum EA, Do Vale HF, Casati MZ, Sallum AW, Stewart B. Efficacy of a combined in-office/home-use desensitizing system containing 8% arginine and calcium carbonate in reducing dentin hypersensitivity: an 8-week randomized clinical study. Am J Dent. 2015 Feb;28(1):45-50. PURPOSE: To determine the efficacy in reducing dentin hypersensitivity (DHS) of a combined in-office and home-use desensitizing system, each product containing 8% arginine and calcium carbonate (Test), following a dental scaling procedure, compared to the combination of a conventional prophylactic paste and a potassium nitrate dentifrice (Control), in a group of patients with known dentin hypersensitivity. METHODS: An 8-week clinical study, with 50 subjects, was conducted in Piracicaba, São Paulo, Brazil, using a double-blind/two treatment design. Air blast sensitivity assessments were used to compare the efficacy of the two approaches using both the Schiff scale as well as a Visual Analogue Scale (VAS). RESULTS: Immediately after prophylaxis, the Test treatment provided significant reduction in DHS when compared to baseline values (VAS = 26.2% and Schiff = 29.1%), while for Control treatment this difference was not statistically significant (VAS = 8.1% and Schiff = 6.6%). The comparison between groups after prophylaxis showed a greater DHS reduction for the Test treatment (P < 0.05). The reductions in DHS after 2, 4 and 8 weeks were significant for both groups, however, when considering Schiff scale, the Test treatment provided greater DHS reduction after 2 weeks (44.5% for Test versus 27.7% for Control) and 4 weeks (55.2% for Test and 40.5% for Control), while after 8 weeks there was no significant difference between groups (71.1% for Test versus 61.1% for Control). 1. What is the study design? A. Randomized clinical study B. Case-control C. Cohort D. Case report 2. According to what is reported in the abstract, what type of blinding was there? A. Single blinded B. Doubleblinded C. Tripleblinded 3. What was the outcome? A. Schiff scale B. Visual analogue scale(VAS) C. Prophylaxis D. All the above E. AandB [study questions]

1. A 2. B 3. E

___________ and __________ studies measure disease occurrence and its association with an exposure by having a temporal dimension (i.e., prospective or retrospective study design).

Case-control and cohort studies measure disease occurrence and its association with an exposure by having a temporal dimension (i.e., prospective or retrospective study design).

Read the following and answer questions 2-3 below. In a study assessing the association between body mass index and periodontitis, subjects' periodontal status was examined by one of three trained dentists. Body mass index is calculated from height and weight. In this study, height and weight were self-reported. Periodontal status was assessed by measuring pocket depth and attachment loss. 2. Height and weight were self-reported. Assume that most people will overestimate their height and underestimate weight. If we compared the self-reported measurements to measurements taken by a clinician, this would be an example of assessing A. Reliability B. Validity 3. Before the study, the three dentists were calibrated to ensure that they measured pocket depth and attachment loss consistently to each other. This was done to improve A. Reliability B. Validity [study questions]

2. B, 3. A

Read the following and answer questions 4-5 below. The Oral Glucose Tolerance Test is considered a gold standard for diagnosing diabetes. It requires a fast of at least 8 hours, then blood drawn every hour for 2-3 hours after drinking a glucose liquid. An alternative is measuring fasting plasma glucose, a single blood test after an 8 hour fast. The test is considered positive for diabetes when fasting plasma glucose is at least 126 mg/dL. Assume now that the cut-off for screening is lowered from 126 mg/dL to 120 mg/dL 4. How would this change in diagnostic criteria affect the specificity of diagnosing diabetes? A. Specificity would increase B. Specificity would decrease C. No change 5. How would this change in diagnostic criteria affect the rate of false negatives? A. False negative rate would increase B. False negative rate would decrease C. No change [study questions]

4. B, 5B

Please read the abstract below and answer questions 6-7. Adapted from: T. Iinuma1 et al., Denture Wearing during Sleep Doubles the Risk of Pneumonia in the Very Elderly, Journal of Dental Research Poor oral health and hygiene are increasingly recognized as major risk factors for pneumonia among the elderly. To identify modifiable oral health-related risk factors, we prospectively investigated associations between a constellation of oral health behaviors and incident pneumonia in the community-living very elderly (i.e., 85 years of age or older). At baseline, 524 randomly selected seniors (228 men and 296 women; mean age, 87.8 years) were examined for oral health status and oral hygiene behaviors as well as medical assessment, including blood chemistry analysis, and followed up annually until first hospitalization for or death from pneumonia. During a 3-year follow-up period, 48 events associated with pneumonia (20 deaths and 28 acute hospitalizations) were identified. Among 453 denture wearers, 186 (40.8%) who wore their dentures during sleep were at higher risk for pneumonia than those who removed their dentures at night. Overnight denture wearing was independently associated with an approximately 2.38-fold higher risk of the incidence of pneumonia (Risk Ratio = 2.38, 95% confidence interval 1.25 - 4.56). 6. What could you conclude about the relationship between denture wearing during sleep and pneumonia in the elderly? A. Overnight denture wearing was associated with a preventive effect against pneumonia B. Overnight denture wearing was positively associated with pneumonia C. Overnight denture wearing caused pneumonia D. No association was found 7. What was the risk of a pneumonia-related event (defined as hospitalization or death from pneumonia) in the entire study population? A. 186/524 over 3 years B. 48/453 over 3 years C. 48/524 over 3 years D. 186/453 over 3 years [study questions]

6B, 7C

1. What does PICO Stand for? A. Patient, Intervention, Comparison, Outcome B. Patient, Intervention, Comparison, Outlook C. Prevention, Intervention, Collaboration, Outcome D. Prognosis, Implementation, Comparison, Outlook [study questions]

A

10. In a paper by Raman et al. (published in 2014), the authors compared people who received nonsurgical periodontal therapy (NSPT) against people who received oral hygiene instructions (OHI). The authors wrote that the difference in mean (average) plaque index between the NSPT and OHI groups was statistically significant, with a p-value of 0.013, when the subjects returned for a visit after two months. Which of the following is CORRECT? A. There IS EVIDENCE that the difference in mean plaque index between the two groups is systematic (real), as opposed to being due to random variation/chance fluctuation B. There is NO EVIDENCE that the difference in mean plaque index between the two groups is systematic (real). The difference is most likely due to random variation/chance fluctuation. [study questions]

A

5. Case-Control Studies are good at studying A. Outcomes/diseases that are rare B. Exposures that arerare C. Incidence (rate) of outcomes between groups [study questions]

A

6. Which of these is a complete citation? A. Am J Dent. 2016 Feb;29(1):58-64. A randomized clinical trial in subjects with dry mouth evaluating subjective perceptions of an experimental oral gel, an oral rinse and a mouth spray compared to water. Jose A, Siddiqi M, Cronin M, DiLauro TS, Bosma ML B. Fox, Philip C., et al. "Pilocarpine treatment of salivary gland hypofunction and dry mouth (xerostomia)." 151.6 (1991): 1149-1152. C. Närhi, T. O. "Prevalence of subjective feelings of dry mouth in the elderly." Journal of dental research 73.1: 20-25. D. doi: 10.1097/j.pain.0000000000000149. Combination of morphine with nortriptyline for neuropathic pain. Gilron I1, Tu D, Holden RR, Jackson AC, DuMerton-Shore D.

A is answer. Explanation: These answers represent some different citation styles, but the style does not bear on whether or not the citation is complete. B is missing the journal title, C is missing the year, and D is missing the year, volume, issue, and journal title.

Informed Consent language and its documentation must be writte in ______ language.

A process, not just a form. Information must be presented to allow people to voluntarily decide whether or not to participate. Must educate participants in terms that they can understand. Therefore, informed consent language and its documentation must be written in "lay language". [RCT]

St 1. Systematic reviews provide results that can be generlized more broadly than individual studies. St 2. Because resutls are more broad, Systematic Reviews are less reliable and accurate than individual studies. St 3. One disadvantage of Systematic Reviews is that they are time consuming. St 4. One advantage of Systematic Reviews is the ease of combining study data. [imp]

Advantages and Disadvantages of Systematic Reviews: Advantages: 1. Broad review of the literature and other resources (unpublished studies, ongoing research). 2. Results can be generalized more broadly than individual studies. 3. More reliable and accurate than individual studies. Disadvantages: 1. Time-consuming 2. May not be easy to combine study data

Advantages and Disadvantages of Meta-Analysis [imp] Advantages: 1. Greater _____ power. 2. Greater ability to _________. 3. Considered an ______ resource. Disadvantages: 1. Difficult to ___________ appropriate studies. 2. _________ provide adequate data for inclusion and analysis. 3. Requires advanced ______ techniques.

Advantages: 1. Greater statistical power 2. Greater ability to extrapolate to general population 3. Considered an evidence-based resource Disadvantages: 1. Difficult to identify appropriate studies 2. Not all studies provide adequate data for inclusion and analysis 3. Requires advanced statistical techniques

Advantages and Disadvantages of Randomized Controlled Trial (RCT) [imp] 1. Randomization can remove possible ______ bias. 2. Is blinding possible? 3. Can results be analyzed with well known statistical tools? 4. Are populations of participating individuals clearly identified? 5. Does randomizaiton assist with statistical analysis? 6. Is conducting and RCT expensie or inexpensive?

Advantages: 1. Randomization can remove possible population bias 2. Blinding is possible 3. Results can be analyzed with well known statistical tools 4. Populations of participating individuals are clearly identified 5. Randomization assists with statistical analysis Disadvantages: 1. Expensive (time & money). 2. Volunteer Bias possible. 3. Can be ethically problematic.

1. Investigating the association between prosthetic joint replacement and periodontal bone loss. She will have two groups in her study: people with prosthetic joint replacement, and people without prosthetic joint replacement. She will then compare these two groups in terms of periodontal bone loss. She thinks that age might be a confounder. Therefore, for each person in the "prosthetic joint replacement" group, she makes sure there is a specific counterpart in the "no prosthetic joint replacement" group who has the same age. What strategy is she using to reduce or avoid confounding? A. Restriction B. Matching C. Stratification D. Selection bias E. Experimenter bias [study questions]

B

3. When participants drop out of a study and the researchers use the data without including the participants who dropped out, which of the following biases is most likely to occur? A. Social desirability bias B. Selection bias C. Confounding bias [study questions]

B

3. Which of the following statements about randomization is/are TRUE? a) Randomization guarantees that your groups will be balanced in terms of age, gender, etc. b) In some cases, it is not ethical or feasible to do randomization c) Both of the above d) Neither of the above

B

4. Using a double-blind study is a way to reduce or eliminate which of the following? A. Selection bias B. Experimenterbias C. Neither of the above [study questions]

B

6. What is the definition of a p-value? A. The chance of getting a difference equally big (or SMALLER) than the one we observed in our actual sample, supposing that the NULL hypothesis is true B. The chance of getting a difference equally big (or BIGGER) than the one we observed in our actual sample, supposing that the NULL hypothesis is true C. The chance of getting a difference equally big (or SMALLER) than the one we observed in our actual sample, supposing that the ALTERNATIVE hypothesis is true D. The chance of getting a difference equally big (or BIGGER) than the one we observed in our actual sample, supposing that the ALTERNATIVE hypothesis is true [study questions]

B

9.What is the domain for the following question?: Are pediatric patients with Autism Spectrum Disorder compared to pediatric patients without Autism Spectrum Disorder at an increased risk for caries? A. Therapy B. Prognosis C. Diagnosis D. Etiology/Harm

B is answer. Explanation: Question domains can get tricky, but here are a few tips... Look at the problem the patient has and how you are responding to it to determine the domain. Diagnosis: Determine the problem. Therapy: How to best treat the problem. Etiology/Harm: What causes the problem or a negative impact from intervening for the problem. Prognosis: What will the problem look like over time based on factors other than your treatment or anything else you are doing/administering to your patient. Economic Analysis: How much will this problem cost or what is the cost/benefit of treating the problem with this intervention. Sometimes people have difficulty determining the difference between PROGNOSIS and *THERAPY*. A therapy question concerns something you are doing to the patient (or having the patient do to themselves) as a treatment. A prognosis question, though, looks at some factor OTHER than treatment and its impact on prognosis. In our sample above, we can tell it is a prognosis domain because you the dentist did not give your patient Autism Spectrum Disorder, and it is the impact of this condition that we are looking at over time.

1. Prospective cohort studies are ideal for studying: A. Diseases that develop over a long period of time (long latency) B. Outcomes/diseases that are rare C. Exposures that are rare

C

9. Which of the following statements about hypothesis testing is/are TRUE? A. It is POSSIBLE for a p-value to be a negative number B. When written as a decimal, it is POSSIBLE for a p-value to be above 1.00 C. The alternative hypothesis is ALWAYS the opposite of the null hypothesis D. Both (a) and (b) are true E. Both (a) and (c) are true F. Both (b) and (c) are true [study questions]

C

In PubMed, combining two search terms with the connector 'OR' will: A. Retrieve only articles that mention both B. Be useful when filtering terms unrelated to the concept. C. Retrieve articles about either term, but not necessarily both. D. Retrieve a set that is smaller than the results would be for either term separately.

C

5. In PubMed, combining two search terms with the connector 'AND' will: A. Retrieve articles about either term, but not necessarily both B. Be useful when combining all terms about the same concept C. Retrieve only articles that mention both terms D. Retrieve a set that is larger than the results would be for either term separately [study questions]

C. Explanation: A, B, and D describe what happens when you combine search terms in PubMed using 'OR.'

3. Plain Language Summaries are a type of filtered information that may be found where? A: PubMed B: Cochrane C: ADA's EBD website D: A & C [study questions]

C. Explanation: While both PubMed and Cochrane contain other types of filtered information, only the ADA's EBD website contains Plain Language Summaries.

What level of evidence is described: Clinicians are observing as well as reporting. Often provides information regarding NEW disease or adverse effects, and may lead to hypothesis formatoin. No comparison group.

Case Report/Case Series: - Clinicians observing and reporting. - Often provide information regarding new disease or adverse effects. - May lead to hypothesis formation. - Simple description of individual patient W/O comparison group.

St 1. Case Reports/Series are very expensive, but easy to use. St 2. Case Reports provie information about disease or treatment and are good for hypothesis generating. St 3. Case Reports/Series are good for hypothesis GENERATING, but are not able to test the hypothesis. St 4. Data from Case Reports/Series may have biased selection and thus is not necessarily generalizable information. [imp]

Case Reports/Series : Strengths: - inexpensive and easy. - provides information about disease or treatment. - good for generating hypothesis. Weakness: - not necessarily generalizable information due to BIASed selection. - Not able to test hypothesis .

Determine which of the descriptions is for Case-Control and which for Cohort study: a. Subjects are grouped by EXPOSURE. b. Subjects are grouped by DISEASE status. c. Compare odds of exposure/prevalence between groups. d. Compare incidence (rate) between groups.

Case-Control: subjects grouped by DISEASE STATUS; compare odds of exposure/prevalence between groups. Cohort: subjects grouped by EXPOSURE; compare incidence (rate) btwn groups.

8. Dr. Y is studying whether people who grind their teeth are more likely to have a sleep disorder than people who don't grind their teeth. He recruits 200 patients, 100 of whom grind their teeth, for his study. He records whether each patient has a sleep disorder. Which of the following would be the MOST evidence that there is a "real" systematic difference between the tooth-grinding group and the non-tooth-grinding group, as opposed to a difference due to random variation? A. In the tooth-grinding group, 25% have a sleep disorder; in the non-tooth-grinding group, 20% have a sleep disorder B. In the tooth-grinding group, 30% have a sleep disorder; in the non-tooth-grinding group, 15% have a sleep disorder C. In the tooth-grinding group, 35% have a sleep disorder; in the non-tooth-grinding group, 10% have a sleep disorder D. In the tooth-grinding group, 40% have a sleep disorder; in the non-tooth-grinding group, 5% have a sleep disorder [study questions]

D

8. Which statement about MeSH (Medical Subject Headings) is true: A. MeSH are assigned to articles in PubMed by computers B. MeSH represent every concept in the biomedical literature C. Every article in PubMed is tagged with MeSH D. An article may be tagged with a MeSH, for example, Quality of Life [MeSH term] even if the exact words "quality of life" do not appear anywhere in the article.

D is answer. Explanation: A is not correct because MeSH are assigned to articles in PubMed by staff at the National Library of Medicine (aka, human beings), who read the articles and determine the MeSH that represent the concepts discussed in the article. B is not correct because some terminology does not have MeSH to represent it, such as new words in the field, some dental concepts, and trade names. C is not correct because it takes a few weeks (and sometimes longer) to process articles and assign MeSH tags, however these articles are still viewable in PubMed in the interim.

Type of study used to describe characteristics of a population of phenomenon (e.g., new condition) that focuses on "what" rather than "how/when/why".

Descriptive Studies

In which type of studies is information collected without changing the environment (i.e., nothing is manipulated)? Hint: they are NOT truly experimental. a. descriptive b. analytical c. experimental

Descriptive studies

Why work top to bottom in the evidence pyramid? A. less bias and confounding at the top B. fewer items at the top and thus less to search through C. always the best items with the most evidence at the top D. the unfiltered literature is at the top of the pyramid and allows one to quickly isolate individual useful studies E. A & B

E. Explanation: C is not always correct because poorly-executed filtered literature, while still located at the top of the pyramid, does not provide the intended value and therefore is less useful than a well-done original study (unfiltered literature), which is further down in the pyramid. D is incorrect because the unfiltered literature is toward the bottom of the pyramid, not the top. In addition, in order to search the literature most efficiently, one would search the filtered literature first, appraise that literature, and identify the well-done filtered literature before relying on an individual study to make decisions about a patient.

4. When selecting keywords from your PICO to search in PubMed, which of these questions should be considered? A: Is the concept implied? B: Does the term have different meanings depending on the discipline? C: Does each PICO element have a matching keyword? D: A & C E: A & B F: B & C [study questions]

E. Explanation: C is incorrect because you do not necessarily need a keyword for every element of a PICO. You may not include any information for, for instance, the O if the outcome is implied by your other keywords.

Which type of study is described here? Involves groups or population, NOT individuals. Can compare trends over time. Can correlate frequency of a disease in a population. a. Case Report b. Case Series c. Cross-Sectional d. Ecological

Ecological Studies

Epidemiology - Definition: Epidemiology is the study of the _________ (frequency, pattern) and _________ (causes, risk factors) of ________________ in _________________, and the _______________ of this study to the control of health problems.

Epidemiology is the STUDY (scientific, systematic, data-driven) of the DISTRIBUTION (frequency, pattern) and DETERMINANTS (causes, risk factors) of HEALTH-REALTED STATES AND EVENTS (not just diseases) in SPECIFIED POPULATIONS (patient is community, individuals viewed collectively), and the APPLICATION of (since epidemiology is a discipline within public health) this study to the control of health problems. - Epidemiology is not just "the study of" health in a population; it also involves applying the knowledge gained by the studies to community-based practice. - Like the practice of medicine, the practice of epidemiology is both a science and an art. - To make the proper diagnosis and prescribe appropriate treatment for a patient, the clinician combines medical (scientific) knowledge with experience, clinical judgment, and understanding of the patient. - Similarly, the epidemiologist uses the scientific methods of descriptive and analytic epidemiology as well as experience, epidemiologic judgment, and understanding of local conditions in "diagnosing" the health of a community and proposing appropriate, practical, and acceptable public health interventions to control and prevent disease in the community.

5. Which of the below is NOT a way to reduce or avoid confounding? A. Restriction B. Matching C. Randomization D. Stratification E. Multivariate analysis F. All of the above are ways to reduce/avoid confounding [study questions]

F

Match the following terms regarding Randomized Controlled Trial: 1. Parallel Group 2. Split Mouth 3. Crossover a. studies in which subject receives greater than or equal to 2 treatments in sequence, subject can serve as own control b. comparisons are made between two randomly assigned groups. Subjects remain in the same group for the entire study. c. subject receives greater than or equal to 2 treatments, each to a separate section of the mouth.

Parallel group - comparisons are made between two randomly assigned groups. Subjects remain in the same group for the entire study. Split mouth - subject receives greater than or equal to 2 treatments, each to a separate section of the mouth. Crossover - studies in which subject receives greater than or equal to 2 treatments in sequence, subject can serve as own control [RCT]

What type of study is described here? Carried out from the present time into the future. An outcome or disease-free study population is first identified by the exposure or event of interest and followed in time until the disease or outcome of interest occurs. Exposure is identified before the outcome, therefore there is temporal framework to assess CAUSALITY - potential to provide strong evidence.

Prospective Cohort Studies

_________ is used to assign participants into different groups with the expectation that these groups will not differ in any significant way other than treatment and outcome. Therefore.... it: Helps PREVENT bias. and Produces the comparable groups.

Randomization [RCT]

What type of study is described here? All intervention groups are treated identically except for the experimental treatment. The only expected difference between the groups is the outcome variable being studied.

Randomized Controlled Trial (RCT).

What type of study is described here? Considered "gold standard". Most rigorous way of determining whether a cause-effect relation exists between treatment (exposure) and outcome. A study design that randomly assigns participants into an experimental/intervention group or a control/placebo group.

Randomized Controlled Trial (RCT).

_______ is frequently rate-limiting step in a RCT. What are barriers to this step? How is it accomplished (methods)?

Recruitment of participants is frequently rate-limiting step in a RCT. - Barriers to recruitment include participant factors (health, time, travel, fear of research, lack of interest or understanding) and from investigator factors (losing control over patient care, competing interests, lack of engagement - Methods: word of mouth, informing clinic patients, advertising (flyers, papers, online), specific clinical trial websites. [RCT]

St1: it is important to blind the least amount of individuals as possible in a RCT. St 2: Blinding can be single or double, but never triple. St 3: Only participants can be blinded.

St 1 is False - important to blind as many individuals as possible in an RCT. St 2 is false - single blinded, double blinded, or triple blinded. St 3 is false - Ppl that can be blinded = Participants, Practitioners (surgeons, nurses, dietitians, dentists, etc), Data Collectors, Outcome assessors, Data analysts. [RCT]

St1: Certain study procedures may begin until letter of approval or exemption is received from the IRB. St2: Clinical studies, recruitment, screening, and enrollment may ONLY begin upon receipt of the notice of IRB approval.

St 1 is false - NO study procedures can begin until letter of approval or exemption is received from the IRB. St 2 is true. [RCT]

St 1. Ecological studies are good for hypothesis generating. St 2. Ecological studies are able to determine causality.

Strengths and Weaknesses of Ecological Studies [imp] Strengths: - good for hypothesis generating. - conducted on available data. Weaknesses: - correlation does not equal causation. - not possible to link the presence of diseases w. presence of risk factor (NOT determine causality).

Strengths and Weaknesses of Case-Control Studies [imp] 1. Good for examining rare ______. 2. Are they good for diseases with long latency period or is that a different study type? 3. Are they expensive or no? Quick to do or take a long time? 4. Are they subject to bias? 5. Can you calculate incidence (rate) of disease? 6. Is there always clear evidence of temporal relationship between exposure and disease?

Strengths: - Good for examining rare outcomes/diseases - Good for diseases with long latency period - Relatively quick and inexpensive - Existing records can be used Weaknesses: - Subject to BIAS (e.g., recall, selection, etc.) - Rate of disease (incidence) can not be calculated - Temporal relationship between exposure and disease may not be clear.

Strengths and Weaknesses of Cohort Studies [imp] 1. Can it assess causality? 2. Can eligibilaty criteria be standardized? 3. Can calculate ___. 4. Can be more ethical than conducting______. 5. Good for assessing rare _____. 6. Are there potential unkonwn confounders? 7. Is it always feasible for rare diseases w. long folow up time and large sample size? 8. ____ bias is possible. 9. ___ status may change, weakening the study.

Strengths: 1. can establish timing, can assess causality. 2. Eligibility criteria can be standardized 3. Can calculate rates of disease in exposed vs unexposed groups over time (e.g., incidence, relative risk). 4. Can be more ethical than conducting a RCT. 5. Good for assessing rare exposures. Weaknesses: 1. Potential unknown confounder(s) 2. Not always feasible for rare disease (long follow up, large sample size). 3. Loss to follow-up or withdrawals are possible (attrition bias). 4. Exposure status may change (e.g., quit smoking, lose weight)

3. Which of the following is a way to reduce/avoid recall bias? a) Choosing your groups so that they are equally likely to remember b) Getting information from a survey instead of the medical record c) Using the randomized response technique d) None of the above

a

_________ is an optimal strategy to minimize the likelihood of differential treatment or assessments of outcomes. [RCT]

blinding

Concealment of group allocation from one or more individuals involved in RCT.

blinding [RCT]

2. Which of the following is NOT one of the Bradford Hill criteria for causation? A. Plausibility B. Experiment C. Confidence D. Analogy [study questions]

c

Detailed report on a patient and his/her clinical case.

case report

Detailed report on group of subjects and their clinical cases; similar problem.

case series (not case report!)

2. Read the following statements: (i) If one of the Bradford Hill criteria is not satisfied, this proves that cause-and-effect does not exist (ii) If all 9 of the Bradford Hill criteria are satisfied, this proves that cause-and-effect exists Which of these statements is/are TRUE? a) Statement (i) only b) Statement (ii) only c) Both Statement (i) and Statement (ii) d) Neither Statement (i) nor Statement (ii)

d

Two subcategories of observational study design

descriptive (no comparison) and analytical (with comparison)

"____________the conscientious, explicit, and judicious use of best evidence in making decisions about care of individual patients."

evidence-based medicine

study design where researcher "assigns" exposure is known as? What is the characteristic example?

experimental study design e.g. Clinical Trial

May relate to the environment (e.g., air pollution), lifestyle (e.g., smoking, diet), or inborn or inherited characteristics (e.g., blood type). May also be referred to as "risk factor". a. incidence b. outcome c. exposure

exposure

Follow participants for an appropriate period of time depending on outcome being assessed. [RCT] Delete

follow up