Introduction to Evidence-Based Medicine

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Supplement:
Case 1: Therapy for Strep Throat

The Patient

1. Start with the patient -- a clinical problem or question arises out of the care of the patient.

Henry is an active 5 year old boy. His mother brought him in for a check-up because Henry has had a fever and a sore throat for several days.

You suspect Strep and take a throat culture. The standard treatment for Streptococcal Pharyngitis is oral Penicillin three times a day. However, for Henry and his mother, you are concerned about compliance and the expense of this medication.

You recall that a drug representative recently told you that a daily dose of amoxicillin is just as good as penicillin, but costs less. You want to review the literature before you decide on amoxicillin for Henry and possibly changing your standard practice.

The Question

2. Construct a well-built clinical question derived from the case.

Based on this scenario, choose the best, well-built clinical question:

A. In children with strep throat, is amoxicillin as effective as penicillin for relief of symptoms?

B. What is the best treatment for relieving the symptoms of a sore throat?

C. Is amoxicillin better than penicillin for young children?

The Resource

3. Select the appropriate resource(s) and conduct a search

Based on the best, well-built question, choose the best search strategy to address the question. (These search examples were done in PubMed in October 2003.)

A.

Search

Most Recent Queries

Result

#1

Strep pharyngitis

5782

#2

Search streptococcus

54719

#3

Search amoxicillin

7733

#4

Search penicillin

65312

#5

Search #1 AND #2 AND #3 AND #4
Field: All Fields, Limits: Randomized Controlled Trial,
All Child: 0-18 years

16

B.

Search

Most Recent Queries

Result

#1

Search strep throat

141

#2

Search strep throat
Field: All Fields, Limits: Review

6

C.

Search

Most Recent Queries

Results

#1

Search streptococcus

54719

#2

Search amoxicillin

7733

#3

Search penicillin

65312

#4

Search #1 AND (#2 OR #3) Field: All Fields, Limits: All Child: 0-18 years, English, Randomized Controlled Trial, Human

290

The Evaluation

4. Appraise the evidence for its validity (closeness to the truth) and its applicability (usefulness in clinical practice).

Read the following article, then determine if the article addresses the issues of validity. As stated previously, evaluating the medical literature is a complex undertaking. You will find that the answers to the questions of validity may not always be clearly stated in the article and that you may have to use your own judgment about the importance and significance of each question.

Feder HM, Gerber MA, Randolph MF, Stelmach PS, Paulette S, and Kaplan EL. Once-Daily Therapy for Streptococcal Pharyngitis With amoxicillin Pediatrics 1999 Jan;103(1):47-51.

pdf version | html version

Reproduced by permission of Pediatrics.

[You may find it helpful to print this article.]

Validity Issues: Does the article address:
1. Randomization: Was the assignment of patients to treatment randomized? Yes No
2. Patient follow-up: Were all patients who entered the trial properly accounted and attributed for at its conclusion? Yes No
3. Analysis of patients: Were patients analyzed in the groups to which they were randomized? Yes No
4. Blinding: Were patients, health workers, and study personnel "blind" to treatment? Yes No
5. Baseline characteristics of patients: Were groups similar at the start of the trial? Yes No
6. Treatments: Aside from the experimental intervention, were the groups treated equally? Yes No
Are the results of this study valid? Yes No
This covers the first aspect of evaluating the evidence. There are two additional questions that you need to consider: What are the Results of the study? There was no difference in the two groups at the 18-24 hour follow-up visit. One (1%) child in the penicillin group and none in the amoxicillin had a positive culture for GABHS. There was no statistically significant difference in the rate of treatment failures between the amoxicillin and penicillin groups at 4 to 6 days (11% vs 16%) or at 14 to 21 days (5% vs 3%). There was also no difference in the rate that symptoms resolved. Adverse drug effects were similar, with 10% reporting some side effect in the amoxicillin group and 5% in the penicillin group. All side effects were minor and resolved within 24 hours of stopping the antibiotic. There was no mention of complications such as peritonsillar abscess or rheumatic fever. As shown in an earlier study, once daily dosing with amoxicillin is as effective as three times daily dosing with penicillin. amoxicillin is less expensive than other approved once daily dosing antibiotics. Whether 10-day treatment with once daily amoxicillin is as effective as penicillin V in preventing suppurative and non-suppurative complications remains unanswered. A note of caution, as the authors state in the discussion, the power of this study to demonstrate a statistically significant difference in the effectiveness of the two antimicrobial regimes is limited by the sample size. To be able to show a statistically significant difference, the authors needed to enroll at least 353 subjects in each arm. This study had only 79 participants in the amoxicillin group and 73 in the penicillin group. Reprinted with permission from InfoPOEMS, Inc. (Journal of Family Practice 48(4):253-4, Apr 1999) Are the Results applicable to your patient? For this patient where compliance and cost may be of concern, amoxicillin appears to be as beneficial and perhaps easier to take than penicillin.

The Patient

5. Return to the patient -- integrate the evidence and clinical expertise, patient preferences and apply it to practice.

Think about Henry, your treatment recommendation for him and what you would discuss with his mother.

Revised, October 2004

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Supplement: Case 1: Therapy for Strep Throat

Supplement:
Case 1: Therapy for Strep Throat