THER202 LEC15 Quick Steps in the Critical Appraisal of Articles on Therapy

Ther 202: Pharmacotherapeutics

EXAM

QUICK STEPS IN THE CRITICAL APPRAISAL OF ARTICLES ON THERAPY: EBM FOR THE BUSY CLINICIAN LECTURE 15

25 July 2012

Dr. Cecile A. Jimeno 

OUTLINE I. Critical appraisal II. Steps in critical appraisal III. Evaluating Validity IV. Evaluating Results V. Evaluating Applicability

I. CRITICAL APPRAISAL Objectives of a “Quick” Critical Appraisal 

To review the process of critical appraisal (in relation to an article on therapy)  To learn some simple and efficient ways to obtain valid journal articles  To understand key concepts which are important in doing a good critical appraisal  To practice the skill of critical appraisal Why quick appraisal?  



We need to simplify our retrieval and review of articles We do NOT have to read everything about a specific problem or topic; if we can ask a focused clinical question we can also do a systematic literature search, as well as do an efficient critical appraisal. However, even with a well designed and systematic literature search, we still end up with several journal articles to retrieve and read.

Critical Appraisal 

Technique which increases the effectiveness of reading. Enables readers to exclude studies that are too poorly designed to inform practice.  Allows us to concentrate on a more systematic evaluation of good quality studies & then to extract their salient points. CAT VS Critical Appraisal 

Critical appraisal: the process of evaluating the medical literature for its validity, importance or applicability  CAT= critically appraised topic  CAT is a summary of the process of critical appraisal which is focused on a specific clinical question Appraising an article on claims of effectiveness Guide questions 1. Was the assignment of patients to treatment randomized? 2. Was randomization concealed? 3. Were follow up adequate? 4. Were patients analyzed under the groups to which they were originally randomized? 5. Were the patients, health workers, and study personnel blind to treatment? 6. Were patients in the treatment and control groups similar with respect to known prognostic factors? 7. How large was the treatment effect? 8. How precise was the estimate of treatment effect? 9. Can the results be applied to my patient care? 10. Were all clinically important outcomes considered? 11. Are the likely treatment benefits worth the potential harms and costs?

Comments

VALIDITY

IMPORTANCE /RESULTS APPLICABILITY

II. STEPS IN CRITICAL APPRAISAL 

Answer 3 sets of question (V-I-A) o Are the results of the study valid? (VALIDITY) o What are the results? (IMPORTANCE) o How can I apply the results to patient care? (APPLICABILITY)

III. EVALUATING VALIDITY  

Do the results reflect an unbiased estimate of the treatment effect, or have they been influenced in some systematic fashion to lead to a false conclusion? If the answer is YES, then the study is worth reading

Natividad, Rex, Francis

1

Otherwise, toss it out or look for other articles. Accept it only if there is no alternative.

Appraisal Checklist: RAMMbo Study Biases  To review the process of critical appraisal (in relation to an article on therapy) 1. Recruitment 2. Who did the subjects represent?  Allocation o Central computer randomization is the best to use in allocation concealment and also the most valid. o Use of envelopes in allocation concealment is actually doubtful. o Use of birthdays or assigning alternate days is actually not useful in allocation since these are not randomized.  Was the assignment to treatments randomized? o Randomization is done to make two groups equal, to avoid bias, to ensure 50-50 chance for each patient to be allocated to one group or the other, thus, ensuring that results are seen due to the treatment NOT due to the differences in the characteristics of two groups.  Were the groups similar at the trial’s start? o Check for the baseline characteristics which are usually found in tables in RCTs. 3. Maintenance: Adequate follow-up and Analyzed in the original allocation  Adequate follow-up rate: losses to follow-up o 5% losses to follow up probably lead to little bias o >20% poses serious threats to validity o Characteristics and similarities in the characteristics of losses on each group (e.g. sex, age) are also important and should be checked  Were the groups treated equally? o This applies not only to the intervention or exposure itself but also to the actual care to the subjects of the study (i.e. identical care).  Were outcomes ascertained & analyzed for most patients? o Intention-to-treat principle: analyze participants in the groups to which they were randomized. Exception: if patient is found on BLIND reassessment to be ineligible based on prerandomization criteria. 4. Measurements  Were patients and clinicians “blinded” to treatment? o How about the Participants? Investigators? Outcome assessors? Analysts? o Blinded is done to minimize measurement bias. o Most important to use "blinded" outcome assessors when outcome is not objective! o Papers should report WHO was blinded and HOW it was done.  Were measurements objective & standardized o Measurement is said to be objective if appropriate blinding is maintained all throughout the study. 5. Placebo Effect This is attributable to the expectation that the treatment will have an effect. 6. Chance Effect  Two methods of assessing the role of chance:  P-values (Hypothesis Testing) o Use statistical test to examine the ‘null’ hypothesis

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Ther 202 DRUG INTERACTIONS AND PHARMACOVIGILANCE o

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