Case designs
Download
1 / 61

case designs - PowerPoint PPT Presentation


  • 155 Views
  • Updated On :

Case Designs. Reports that cover the management of a single patient or a series of patients . Three types of case designs. Case Report An article that describes the clinical course of 1 or 2 patients Typically consist of complaints, examination findings, diagnosis, treatment, and outcome

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'case designs' - betty_james


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Case designs l.jpg

Case Designs

Reports that cover the management of a single patient or a series of patients


Three types of case designs l.jpg
Three types of case designs

  • Case Report

    • An article that describes the clinical course of 1 or 2 patients

    • Typically consist of complaints, examination findings, diagnosis, treatment, and outcome

    • Case reports often provide early evidence of new diseases, treatments, or adverse effects

    • No hypothesis, data analysis, or generalizable conclusion is possible

Evidence-based Chiropractic


Three types of case designs cont l.jpg
Three types of case designs (cont.)

  • Case Series

    • More than 2 case reports in a single paper

  • Single-subject time series design

    • A type of case report that tracks a patient’s condition using multiple sequential assessments during a treatment phase and a phase when they are not being treated

Evidence-based Chiropractic


The purposes and limitations of case reports l.jpg
The purposes and limitations of case reports

Evidence-based Chiropractic


Preparation of case reports l.jpg
Preparation of case reports

  • Does not typically require approval from an Institutional Review Board

  • However, patient confidentiality should be respected

    • Personal information that might identify the patient should not be used

    • Patient photographs require written consent prior to submitting the report for publication

Evidence-based Chiropractic


Reasons case reports are returned to authors for revision l.jpg
Reasons case reports are returned to authors for revision

  • Claims of cause-and-effect relationships between interventions and outcomes

  • Lack of information about the reliability and validity of measurements

  • Lack of detail about the examination and the intervention

  • Lack of detail about decision making

Evidence-based Chiropractic


The evidence based case report l.jpg
The evidence-based case report

  • Designed to illustrate the process of locating and applying evidence to clinical circumstances

    • How evidence can be applied during the various phases of patient care

    • Informative even when little or no high-quality evidence is available

  • They do not report new findings

Evidence-based Chiropractic


Meta analyses of case reports or case series l.jpg
Meta-analyses of case reports or case series

  • Occasionally seen in the literature

  • Sometimes they can draw important new conclusions from the literature

  • Limited statistical analyses may be done

    • e.g., totals, means, proportions, correlation

  • Conclusions may be proven wrong after more definitive research has been done

Evidence-based Chiropractic


Single subject time series designs sstsds l.jpg
Single-subject time series designs (SSTSDs)

  • A study that involves a single patient

  • Repeated measures are taken while an intervention is applied and withdrawn

    • The objective is to observe differences in the outcome measures during each phase

    • Improvement during the intervention phase may mean that the treatment is effective for that patient

Evidence-based Chiropractic


Sstsds cont l.jpg
SSTSDs (cont.)

  • The patient acts as their own control during the no treatment phase

  • Other names for SSTSD

    • Single case experimental design

    • Time series design

    • Small-n design

    • n-of-1 trial

    • Within-subject comparison

Evidence-based Chiropractic


Baseline phase l.jpg
Baseline phase

  • Typically the initial phase of a SSTSD

  • At least 3 repeated measures of the outcomes are taken prior to starting treatment to show that the condition is stable

  • Reveals the natural state of the patient’s condition and becomes the standard for evaluating the effect of treatment

Evidence-based Chiropractic


Intervention phase l.jpg
Intervention phase

  • The phase in which treatment is started

    • Usually follows the baseline phase

  • Outcomes are measured at least 3 times

  • Duration should be the same as the baseline phase

  • Changes in the outcome during this phase can be attributed to the treatment

Evidence-based Chiropractic


Enhanced validity of sstsds l.jpg
Enhanced validity of SSTSDs

  • Evidence derived from SSTDs is more convincing than case reports

  • Repeated measures during the treatment and non-treatment phases reduces the likelihood that the results are due to chance

  • Outcome measures should be objective, measurable, and clinically relevant

Evidence-based Chiropractic


Enhanced validity of sstsds cont l.jpg
Enhanced validity of SSTSDs (cont.)

  • Can be the strongest evidence available regarding an individual patient

    • The best way to establish whether a specific treatment is effective for an individual patient

    • Results may improve confidence in therapeutic decisions

  • However, results cannot be generalized because they only involve a single subject

Evidence-based Chiropractic


Sstsds are quasi experimental l.jpg
SSTSDs are quasi-experimental

  • Independent variables are manipulated (applied and then withdrawn) as in experimental research

  • Case studies may include manipulation of the independent variable but do not measure changes of the dependent variable over repeated observations

Evidence-based Chiropractic


Ab design l.jpg
AB design

  • Where -

    A = baseline or observation phase

    B = intervention phase

  • A fairly weak design because it has very little control over threats to internal validity

  • The outcome must change dramatically to support a cause-and-effect relationship

Evidence-based Chiropractic


Aba design l.jpg
ABA design

  • Involves 3 phases:

    • Baseline, intervention, and follow-up

    • The minimum number a SSTSD should incorporate

  • Provides much stronger evidence in support of a cause-and-effect relationship

    • Especially if the follow-up phase returns to near baseline levels

Evidence-based Chiropractic


Aba design cont l.jpg
ABA design (cont.)

Days or weeks

Evidence-based Chiropractic


Aba design cont19 l.jpg
ABA design (cont.)

  • Additional phases can be added (ABAB) if there is little distinction between phases

    • Sometimes called the withdrawal design

  • Helps to rule out confounding variables so that the treatment effect can be seen more clearly

    • Spontaneous remission, placebo effects, cyclical conditions may still influence results

Evidence-based Chiropractic


Aba design cont20 l.jpg
ABA design (cont.)

  • Chronic conditions that are fairly stable are best suited for SSTSDs

  • Condition should be reversible and return to pre-treatment values in A phase

  • Acute or unstable conditions are not suitable

    • Outcome measures would vary a great deal between phases with or without the intervention

Evidence-based Chiropractic


Sstsds graph l.jpg
SSTSDs graph

Level -

Changes in the value of the dependent variable before and after the intervention

Trend -

Changes in the direction of the dependent variable (accelerating, decelerating, stable or variable)

The slope of a trend refers to the rate of change of the data or the angle that is formed by the data

Evidence-based Chiropractic


Analyzing sstsd graphs l.jpg
Analyzing SSTSD graphs

  • Can be visually inspected to assess patient response by level, trend, and slope

  • The data can also be statistically analyzed

    • Somewhat controversial

  • Both methods were reported to be equally useful

  • Although graphs are more popular and are easier to understand

Evidence-based Chiropractic


Statistical analysis of sstsd data l.jpg
Statistical analysis of SSTSD data

  • Binomial test

    • The probability of getting y number of successes (a positive treatment effect) by chance, given x number of events (pairs of baseline and treatment phases)

    • Limited value because it takes at least five AB pairs, all with a positive treatment effect, to reach the 0.05 level of significance

Evidence-based Chiropractic


Statistical analysis of sstsd data cont l.jpg
Statistical analysis of SSTSD data (cont.)

  • Paired t-test or repeated measures ANOVA

    • Their non-parametric equivalents may be used instead

    • Provide more power than the binomial test because they consider both the direction and magnitude of the treatment effect in each pair

Evidence-based Chiropractic


Abac design l.jpg
ABAC design

  • C represents an alternate treatment

  • Consists of

    • An initial observation phase

    • Followed by treatment B phase

    • Then a second observation phase

    • Finally alternate treatment C phase

  • Must consider the possibility of carry-over effects from the first phase of treatment

Evidence-based Chiropractic


Abac design cont l.jpg
ABAC design (cont.)

The change in level from B to C could the result of a carry-over effect

Evidence-based Chiropractic


Features of conditions that are suitable for the sstsd l.jpg
Features of conditions that are suitable for the SSTSD

  • Condition is chronic

  • Condition is stable

  • Spontaneous remission is not likely

  • Previous treatment has had limited success

  • No concurrent treatment is involved

Evidence-based Chiropractic


Cyclical conditions l.jpg
Cyclical conditions

  • Difficult to investigate with SSTSDs

  • However, replication of cycles by using additional phases in which the outcomes consistently improve when the treatment is applied can add support to a cause-and-effect relationship

Evidence-based Chiropractic


Types of treatment used with sstsds l.jpg
Types of treatment used with SSTSDs

  • Treatments that have a rapid onset of action when applied and a rapid termination of action when withdrawn are best

  • Treatments that continue to act even after they are stopped are less desirable because they require a washout period to allow the outcome measures to return to a baseline state

Evidence-based Chiropractic


Multiple baseline design a k a replicated ab design l.jpg
Multiple baseline design (a.k.a., replicated AB design)

  • Involves 3 or more subjects who have similar complaints and are provided a similar treatment

  • The basic AB design is carried out on each patient, but

    • Baselines are of differing lengths of time

    • There is no withdrawal of treatment

  • Can help control for extraneous variables

Evidence-based Chiropractic


Multiple baseline design cont l.jpg
Multiple baseline design (cont.)

  • As usual, differences in the measurements are analyzed between phases within each subject

  • There is also a comparison across subjects

  • Cause-and-effect is strengthened

    • Because it is not likely that extraneous factors occurred by chance at the specific time treatment was started on each patient

Evidence-based Chiropractic


Slide32 l.jpg

Multiple

baseline

design

Intervention applied

Intervention applied

Intervention applied

Evidence-based Chiropractic


Simultaneous replication design l.jpg
Simultaneous replication design

  • Similar to the multiple baseline design, but all patients start the study at the same time and their scores are tracked concurrently

    • Patient care is not necessarily provided concurrently In multiple baseline studies

Evidence-based Chiropractic


Simultaneous replication design cont l.jpg
Simultaneous replication design (cont.)

  • Treatment is started on the first patient, then in sequence with the other study participants

    • The first patient is started on the treatment at the outset of the study

    • Treatment is withheld from subsequent patients until a treatment effect is discernible in the preceding patient

Evidence-based Chiropractic


Simultaneous replication design cont35 l.jpg
Simultaneous replication design (cont.)

  • This design helps control for confounding factors

  • When treatment is given to one patient and the dependent variable changes, while the baseline measures of the untreated patients remain unchanged, the chance that something outside the study caused the change is reduced

Evidence-based Chiropractic


The n of 1 rct l.jpg
The n-of-1 RCT

  • Described by Sackett et al

  • A single patient is randomly assigned to receive a placebo versus an authentic treatment or medication

  • Blinding is possible when medication is involved since the doctor and patient do not know whether the real medication or a placebo is being used

Evidence-based Chiropractic


The n of 1 rct cont l.jpg
The n-of-1 RCT (cont.)

  • Difficult to perform with manipulation as the independent variable

    • The chiropractor would always know if the treatment was a placebo

    • The patient would most likely be aware of their assignment

  • Although n-of-1 studies with limited randomization and blinding are feasible for chiropractic patients

Evidence-based Chiropractic


Sstsd studies are feasible for practicing chiropractors l.jpg
SSTSD studies are feasible for practicing chiropractors

  • To determine the best form of treatment for a particular patient

    • SSTSDs are are the best form of evidence for this task

  • To reassure the patient and practitioner that the treatment is actually helping

  • To contribute articles to peer reviewed journals

Evidence-based Chiropractic


When to do sstsd studies l.jpg
When to do SSTSD studies

  • When there are doubts about the effectiveness of a planned treatment in a specific patient

    • The patient may have already tried other practitioners and therapies without benefit

    • SSTSD may be useful to see if the planned treatment actually results in improvement

Evidence-based Chiropractic


When to do sstsds cont l.jpg
When to do SSTSDs (cont.)

  • It is not clear if a treatment is actually helping

    • To the patient or practitioner

  • The patient is undergoing another type of treatment or self-treating

    • And it is thought that this treatment may be ineffective or interfering with the patient’s progress

Evidence-based Chiropractic


When to do sstsds cont41 l.jpg
When to do SSTSDs (cont.)

  • The doctor or patient thinks some of the patient’s symptoms may be caused by the treatment

  • There is doubt about what the optimal combination of therapies or frequency of care should be

Evidence-based Chiropractic


When to do sstsds cont42 l.jpg
When to do SSTSDs (cont.)

  • Any time the patient or practitioner has questions about the effectiveness of a patient’s treatment

  • The patient is agreeable and even enthusiastic about participating

    • Is actually a partnership between the clinician and the patient

    • May not work if the patient is non-compliant

Evidence-based Chiropractic


Sstsd ethical concerns l.jpg
SSTSD ethical concerns

  • Denying treatment to patients during the observation phase

    • Only applies to cases where withholding treatment would actually be harmful

    • Chiropractic candidates for SSTSDs are patients with chronic conditions that are not likely to deteriorate during periods of time without treatment

Evidence-based Chiropractic


Sstsd ethical concerns cont l.jpg
SSTSD ethical concerns (cont.)

  • The patient can still receive other forms of treatment in a SSTSD

    • Only the specific intervention under investigation must be withheld

  • Patients should be fully informed about what is involved in the study

    • Signed informed consent

    • They have the right to withdraw at any time and for any reason

Evidence-based Chiropractic


Sstsd ethical concerns cont45 l.jpg
SSTSD ethical concerns (cont.)

  • If the intent of patient care includes the performance of a research project, the patient should be informed they are the object of a scientific investigation

  • Qualifies as research when

    • Data is collected with the intent to publish the results in a journal or present at a conference

    • There is intent to produce new information beyond current standard care

Evidence-based Chiropractic


Sstsd ethical concerns cont46 l.jpg
SSTSD ethical concerns (cont.)

  • Must obtain approval from a legitimate Institutional Review Board before beginning clinical research, even in a private practice setting

  • It may actually be unethical to continue to provide an intervention on an ongoing basis without testing its effectiveness at some point

Evidence-based Chiropractic


Slide47 l.jpg

GraphingSSTSDs

Form can be used to track

patients with low back or neck pain

The patient does not need to return to the office during observation phase, but can take home questionnaires and complete them at scheduled times

Observation

phase

O

Treatment

phase

X

Oswestry Low Back Pain Disability Questionnaire

or Neck Pain Disability Index

Numeric pain scale with 0 = no pain and

10 = worst pain imaginable

Evidence-based Chiropractic


Hypothetical graph l.jpg
Hypothetical graph

O

O

O

O

O

O

X

X

Neck Pain Disability Index

X

X

X

X

O

O

O

O

0-10 Numeric

Pain Scale

O

O

X

X

X

X

X

X

Evidence-based Chiropractic


Appraising case reports l.jpg
Appraising case reports

  • Not much information is available on how to appraise case reports and case series

  • Yet appraisal is necessary in order to gain as much as possible from reading and to avoid wasting time with poorly written articles

Evidence-based Chiropractic


Appraising case reports cont l.jpg
Appraising case reports (cont.)

  • They should adhere to the general format of a scholarly publication and contain the required sections

    • Abstract, Introduction, Case Description, Discussion, and References

  • A red flag if any of these elements are missing or labeled incorrectly

    • Allow for atypical manuscript requirements and use of synonyms

Evidence-based Chiropractic


Appraising case reports cont51 l.jpg
Appraising case reports (cont.)

  • Does the Abstract provide an accurate description of the case and its implications?

    • Readers often assume that abstracts are accurate, but they may not be

    • Frequently the only part of an article that is actually read

    • Abstract should be used as a screening tool to locate interesting articles, then read them

Evidence-based Chiropractic


Appraising case reports cont52 l.jpg
Appraising case reports (cont.)

  • Is the case really unique or uncommon?

    • It is sometimes appropriate to replicate the same topic in several case reports, but eventually new studies should involve more sophisticated designs

    • However, it is common to find many case reports on the same topic about harm associated with treatment

      • Necessary to observe patterns of adverse events that are related to a particular form of treatment

Evidence-based Chiropractic


Appraising case reports cont53 l.jpg
Appraising case reports (cont.)

  • Was the literature review adequate?

    • May be brief, but should call attention to the most current relevant research on the topic

    • An explanation of how the literature relates to the current case

    • References should be derived from valid sources; principally peer-reviewed journals

Evidence-based Chiropractic


Appraising case reports cont54 l.jpg
Appraising case reports (cont.)

  • Was a rationale for reporting the case presented that effectively highlights its importance?

    • An explanation of why the report was written

    • Is the information already common knowledge?

    • Should include a compelling argument to justify the need for writing of the case report

      • If weak, consider not reading the rest of the article

Evidence-based Chiropractic


Appraising case reports cont55 l.jpg
Appraising case reports (cont.)

  • Was the case adequately described in the Case Description section?

    • Described clearly and concisely, yet comprehensively

    • Including the patient’s health history, examination, diagnosis, treatment, and final outcome

      • Details of the treatment (e.g., type, location, and frequency)

      • Should not include irrelevant findings

Evidence-based Chiropractic


Appraising case reports cont56 l.jpg
Appraising case reports (cont.)

  • Was the study population described adequately?

    • A case should be explicitly defined

    • Selection criteria

      • Based on diagnosis; examination, laboratory, or radiographic findings; or condition severity

    • For example, in a series of neck pain patients

      • Case would be defined as pain of mechanical origin, no disc herniation, no radicular pain, etc.

Evidence-based Chiropractic


Appraising case reports cont57 l.jpg
Appraising case reports (cont.)

  • Were the outcome measures suitable for the given clinical circumstances?

    • Must be quantifiable (e.g., pain scores or ROM)

      • A vague statement such as “there was less lumbar muscle spasm” is inadequate

    • Novel diagnostic tests should be fully described, together with normal values

Evidence-based Chiropractic


Appraising case reports cont58 l.jpg
Appraising case reports (cont.)

  • Did the author present convincing evidence in support of the diagnosis that was presented?

    • The diagnosis should be supported by evidence derived from the results of the case and the literature review

    • Differential diagnoses that were considered and why they were eliminated

Evidence-based Chiropractic


Appraising case reports cont59 l.jpg
Appraising case reports (cont.)

  • Did the author point out the study’s limitations and suggest alternate explanations?

    • Limitations should be clearly identified

    • Other possible explanations for the results of the case should be mentioned

      • e.g., natural progression of the condition, extraneous factors, and placebo effects

      • No control group and limited generalizability

Evidence-based Chiropractic


Appraising case reports cont60 l.jpg
Appraising case reports (cont.)

  • Were suggestions for future research offered?

    • This is one of the chief reasons for writing case reports

    • Authors should suggest how the topic should be investigated in future studies

  • Were suggestions provided to assist other practitioners in the management of similar cases?

Evidence-based Chiropractic


Appraising case reports cont61 l.jpg
Appraising case reports (cont.)

  • Was enough evidence presented to support the author’s conclusions?

    • Conclusions should flow logically from the case description

    • No unsupported statements should be offered

      • Especially about the effectiveness of the intervention

      • Or suggest that other practitioners will obtain similar results

Evidence-based Chiropractic


ad