ACTIVITY 8: CASE STUDIES, CROSS-SECTIONAL STUDIES

CROSS-SECTIONAL STUDIES 

• AKA

Prevalence surveys

CROSS-SECTIONAL STUDIES 

• Can be thought of as a

• snapshot (or slice) of time because data are collected and evaluated at a single point in time

CROSS-SECTIONAL STUDIES 
Examine the _

prevalence of a risk factor or disease state within a population over a specific time period (e.g., how many people have the flu in November 2019 in Charleston County, Charleston, SC).

CROSS-SECTIONAL STUDIES 

• More of a _ as opposed to hypothesis testing

• hypothesis generating

CROSS-SECTIONAL STUDIES 

• Not suited for

• testing the effectiveness of interventions

CROSS-SECTIONAL STUDIES 

• Most often used descriptively to

• capture information about a population (eg. disease prevalence) but may also be used to examine associations between an independent (exposure) and a dependent (outcome) variable

  • Causality between an exposure and outcome cannot be established from a cross-sectional study

  • Quick and easy to perform

  • Useful for measuring current health status or setting priorities for disease control

STUDY DESIGN

• questionnaire

• surveys 

QUESTIONNAIRE 

• eg. Answer a census or through mail, telephone call

SURVEYS

• Standardized questionnaire used to describe a population at a given point in time 

• Generally conducted to characterize a populatio

• Can also be generated from electronic medical records (EMRs) or databases containing  large amounts of epidemiologic data (e.g., state health department databases)n

STEPS

1. IDENTIFYING TARGET POPULATION

2. SELECT INDIVIDUALS FROM POPULATION TO COMPLETE QUESTIONNAIRE

3. DATA COLLECTION

4. ANALYSIS

 IDENTIFYING TARGET POPULATION

• Population with desired clinical and demographic  characteristics that will ultimately benefit from generalization of the study findings

• Group to be studied

GENERALIZABILITY

• Refers to the extent to which observations in the study population extrapolates to the overall population of interest

SELECT INDIVIDUALS FROM POPULATION TO COMPLETE QUESTIONNAIRE

• sampling 

• Process of selecting a subset of the target population to conduct a study 

DATA COLLECTION

• Retrospective (eg. Prescription records)

• Prospective (eg. Survey)

NALYSIS

• Purely descriptive 

• Summarizing the characteristics of the population using means and percentages

• Sometimes a researcher may examine an association between two variables collected during the same cross-section in time

• These "analytical cross-sectional studies" have potential biases that should be considered by researchers and this type of analysis should be interpreted cautiously

STRENGTHS

Efficient means of capturing descriptive information about a population at a given point in time

LIMITATIONS

• Bias on sampling and temporality, may not give generalizations

CONCERNS

• Problems are errors in data collection and transient effects that may influence observations

• Inaccuracies in data collection may go unnoticed because there are no prior data for comparison

Transient effect

- are those responses that are affected by event, feeling or other circumstance that happened prior to data collection; it may not reflect actual responses when taken in a different time.

EXAMPLE

P	100 individuals are examined
I	None, just observation
O	Rosacea

CASE REPORT / CASE SERIES 

• Are reports without control groups

CASE REPORT / CASE SERIES 

types 

• case studies 

• case reports

• case series 

Case reports and case series 

are types of descriptive observational studies that do not involve a control group

Cross-sectional, case-control, and cohort studies are

types of analytical observational studies which do involve control groups

CASE REPORT / CASE SERIES 

key characteristics

•  lack of a control or comparison group

CASE STUDY

• A record of descriptive research that documents a practitioner’s experiences, thoughts, or observations related to the care of a single patient 

• Opinion of the physician

CASE REPORTS

• A descriptive record of a single individual (case report) in which the possibility of an association between an observed effect and a specific intervention or exposure (often an unexpected complication of treatment or procedure) based on detailed clinical evaluation and history of the individual 

• Only one individual is followed by the practitioner

CASE SERIES

• A group of records (case studies) that documents a practitioner’s experiences, thoughts, or observations related to the care of multiple patients with similar medical situations 

TYPES OF CASE REPORT

• Disease Identification

• Adverse Drug Reaction (ADR)

• Reporting New Treatment Approach

• Educational

• Quality Assurance

New Treatment Approach

• Generally used to generate a hypothesis for further testing with a more resourceintensive design

• May lead to unsubstantiated use of medications for unapproved indications

Educational

Present a scenario to help clinicians improve practice skills

Quality Assurance

Practice errors can illustrate problems to avoid by other practitioners

case reports

strengths

• Identifies rare occurrences

• Identifies delayed ADRs

• Hypothesis generation

• Requires minimal resources

case reports

weakness

• No casual inference can be made

• Potential reporting bias

• No statistical analysis

• Potential for reporting false results

Case Series

strengths 

• Study results are closer to those of routine clinical practice

• May be useful when a randomized controlled trial is challenging to conduct

• High external validity

• Cost-effective and time-saving design

Case Series

weakness

• No casual inference can be made

• Susceptible to selection and measurement bias

• An absolute risk cannot be calculated

• Data collection may be incomplete

CASE REPORT / CASE SERIES

_ type of evidence relating to EBM practices and research

weakest 

CASE REPORT / CASE SERIES

• When possible, results should be

confirmed with randomized controlled clinical trials

CASE REPORT / CASE SERIES

• Useful for

• early recognition of drug toxicities and teratogenicity

• Can be the stimulus to remove a harmful medication from the market

CASE REPORT / CASE SERIES

example 

• The first case reports related specifically to trovafloxacin-induced acute hepatitis were described in February 2000.

• After further consideration of the totality of information related to liver dysfunction, the FDA subsequently removed trovafloxacin from the market in late 2000.

CASE REPORT / CASE SERIES

Can describe and recognize _

new diseases, report new or unusual side effects of medications, or detail rare clinical manifestations and presentations of currently known diseases

CASE REPORT / CASE SERIES

example 

• In 1981 the Centers for Disease Control and Prevention (CDC) detailed the cases of five young men who were treated for Pneumocystis carinii pneumonia at three hospitals in Los Angeles, California.

• These would be the first reports of human immunodeficiency virus and acquired immunodeficiency syndrome in the United States.

EXAMPLE OF CASE STUDIES

1. Nurse’s Pediatric pain management practices – explore pediatric pain management practices

2. Quality of care for complex patients at Nurse Practitioner-Led Clinics (NPLCs)

Nurse’s Pediatric pain management practices – explore pediatric pain management practices

• Picture about actual pain management practices

• Questionnaire data about nurses’ knowledge about pediatric pain management practices and how well they felt they managed pain in children

• Questionnaire data on how critical nurses perceived pain management tasks to be

Quality of care for complex patients at Nurse Practitioner-Led Clinics (NPLCs)

• Review of documentation

• Interview nurse practitioners practicing at NPLCs to determine perceptions of the impact of the NPLC model on quality of care provided to patients with multimorbidity