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Appraising a Therapy Article

Appraising a Therapy Article. Kimberly Pendell. Patient Story. An ER resident is looking for evidence to aid in the treatment of a patient:

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Appraising a Therapy Article

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  1. Appraising a Therapy Article Kimberly Pendell

  2. Patient Story • An ER resident is looking for evidence to aid in the treatment of a patient: • 9 month old feverish girl with noted sores in her mouth for 2 days. She is restless and crying. The mother reports that her daughter is resisting her bottle • Resident suspects herpes gingivostomatitis and is wondering about the effectiveness of oral acyclovir

  3. Pico Question P – In young children with possible herpes gingivostomatitis I – How good is oral acyclovir C – Compared to placebo O – In the rate of curing herpes gingivostomatitis?

  4. Search & Study Citation PubMed  Clinical Queries: • Therapy • Specificity • Acyclovir AND Gingivostomatitis Amir J, Harel L, Smetana Z, Versano I. Treatment of herpes simplex gingivostomatitis with aciclovir in children: a randomised double blind placebo study. BMJ 1997; 314:1800-3.

  5. Methods

  6. Methods • Design • Randomized double-blind placebo controlled study • Setting • Day care unit of tertiary pediatric hospital • Population • 72 children ages 1-6 years old • Signs and symptoms of the illness for less than 72 hours

  7. Methods • 10 children were excluded from the clinical evaluation due to having negative viral cultures • 1 child dropped out of the study before completion • Final study population: 61 • 31 received acyclovir and 30 received placebo

  8. Methods • Intervention: • Acyclovir 15 mg/kg, 5xday/7 days or placebo for same frequency • Main outcome measures: • The efficacy with which the lesions are resolved after 7 days

  9. Validity

  10. Issues of Validity • Is the study a Randomized Trial? • YES • Randomization is important because . . . • Randomization helps eliminate bias that can lead to false results.

  11. Issues of Validity • Was the study sufficiently long and complete? And were all the patients accounted for? • YES • Accountability is important because . . . • Patients not accounted for at a study’s end may have very different outcomes than those still in the study.

  12. Issues Of Validity • Was the follow-up long enough? • YES • Follow-up is important because . . . • If a study is too short, then we may not be able to distinguish between a true and a false association.

  13. Issues of Validity • Were all patients analyzed in the groups to which they were randomized? • YES, for 61 patients • Intention to treat is important because . . . • The intention to treat analysis preserves the value of randomization.

  14. Issues of Validity: Finer Points • Patients and clinicians kept “blind” to treatment? • Groups treated equally? • Groups similar at the start of the trial?

  15. Results

  16. Results • 61 patients completed the study • At the end of the treatment, lesions were present: • In 2 out of 31 acyclovir recipients • In 21 out of 30 placebo recipients

  17. Results CER (Control Event Rate) = 21/30 EER (Experimental Event Rate) = 2/31 • CER and EER are used in calculations to describe effects of treatment • We are interested in effects where the experimental treatment reduces the probability of bad outcomes (e.g. prolonged lesions)

  18. Results ARR (Absolute Risk Reduction) • The absolute mathematical difference between rates of bad outcomes in the control and experimental groups in a trial ARR = CER – EER 21/31 – 2/30 = 0.7 – 0.0645 = 0.63, 95% CI [0.45,0.82] • 63% of patients receiving acyclovir will have a resolution of lesions that they would not have had with placebo.

  19. Results NNT (Number Needed to Treat) • The number of patients who need to be treated to achieve one additional favorable outcome. NNT = 1/ARR = 1/0.63 = 2, CI [1.2, 2.2] • For every 2 patients treated with acyclovir, 1 will respond favorably beyond the results seen with placebo.

  20. Results: Worst Case Scenario • Now consider the study as if all original 72 patients completed the trial: CER = 21/36 EER = 7/36

  21. Results: Worst Case Scenario Using the Risk Reduction Calculator: ARR = 0.39, CI [0.18, 0.60] NNT= 3, CI [2,5]

  22. Other Outcomes • Median values of duration for acyclovir vs. placebo: • Oral lesions: 4 vs. 10 days • Fever: 1 vs. 3 days • Drinking difficulties: 3 vs. 6 days

  23. Applicability, Limitations, Concerns • The study children are somewhat older than our patient • Could these results be applied to younger or older children? • Is acyclovir affordable and accessible for our physician’s patient(s)?

  24. Resolution of Our Story • Our physician prescribed acyclovir • The patient began taking her bottle without fussing and improved in 3 days • The sores healed in 7 days

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