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You just saw a nine-year old patient with common warts on her hands. She is an ideal candidate for cryotherapy. Her mother has heard about treating warts with duct tape and wants to know if you would recommend this treatment.
OBJECTIVE: To determine if application of duct tape is as effective as cryotherapy in the treatment of common warts. DESIGN: A prospective, randomized controlled trial with 2 treatment arms for warts in children. SETTING: The general pediatric and adolescent clinics at a military medical center. PATIENTS: A total of 61 patients (age range, 3-22 years) were enrolled in the study from October 31, 2000, to July 25, 2001; 51 patients completed the study and were available for analysis. INTERVENTION: Patients were randomized using computer-generated codes to receive either cryotherapy (liquid nitrogen applied to each wart for 10 seconds every 2-3 weeks) for a maximum of 6 treatments or duct tape occlusion (applied directly to the wart) for a maximum of 2 months. Patients had their warts measured at baseline and with return visits. MAIN OUTCOME MEASURE: Complete resolution of the wart being studied.
RESULTS: Of the 51 patients completing the study, 26 (51%) were treated with duct tape, and 25 (49%) were treated with cryotherapy. Twenty-two patients (85%) in the duct tape arm vs 15 patients (60%) enrolled in the cryotherapy arm had complete resolution of their warts (P =.05 by chi(2) analysis). The majority of warts that responded to either therapy did so within the first month of treatment. CONCLUSION: Duct tape occlusion therapy was significantly more effective than cryotherapy for treatment of the common wart.
The comparison is what the treatment is tested against.
Could be a different diagnostic test, another therapy, placebo, or no treatment at all.
INTERVENTION: Patients were randomized using computer-generated codes to receive either cryotherapy (liquid nitrogen applied to each wart for 10 seconds every 2-3 weeks) for a maximum of 6 treatments or duct tape occlusion (applied directly to the wart) for a maximum of 2 months.
Attrition: Were patients lost to follow-up, and if so, why?
Intention to treat: subjects are analyzed according to the categories into which they were originally randomized.
Benefits of a treatment are more difficult to demonstrate with intention-to-treat analysis.
Helps to mitigate differences by including subjects who are unlikely to have experienced benefit from the intervention.
Six patients from cryotherapy group and 4 patients from the duct tape group were lost to follow-up (16% of patients). Worst case scenario: 6 cryotherapy patients had wart resolution and the 4 duct tape patients had residual wart. Wart resolution would then be: duct tape 78% and cryotherapy 68% (95% CI, -17 to 28) – therefore not a statistically significant difference between the two treatments. Christakis DA, Lehmann HP. Is duct tape occlusion therapy as effective as cryotherapy for the treatment of the common wart? Arch Pediatr Adolesc Med, Oct 2002; vol. 156; 975-977.
Best Type of Study for Your Question Type of Question Suggested Best Type of Study Therapy RCT > cohort > case control > case series Diagnosis Prospective, blind comparison to gold standard Etiology / Harm RCT > cohort > case control > case series Prognosis Cohort study > case control > case series Prevention RCT > cohort study > case control > case series Clinical Exam Prospective, blind comparison to gold standard Cost Economic analysis Questions of therapy, etiology and prevention which can best be answered by RCT can also be answered by a meta-analysis or systematic review.