[An end to office hours for warts? A randomized study of the effectiveness of liquid nitrogen and of the Histofreezer]. / Het einde van het wrattenspreekuur? Een gerandomiseerd onderzoek naar de effectiviteit van vloeibare stikstof en van de Histofreezer.

ABSTRACT

OBJECTIVE: Comparison of the effectiveness of liquid nitrogen and of cryotherapy by means of the Histofreezer in the treatment of hand warts. DESIGN: Randomized therapeutic trial. SETTING: Six general practices in Limburg, The Netherlands. PATIENTS AND METHODS: Of the patients 43 (with 83 warts) were treated with nitrogen (if necessary twice) and 50 (with 108 warts) with the Histofreezer (if necessary 4 times), with a final control visit after 2.5 months. After a training session, the general practitioners performed the treatments and the observations. In these groups, 7 patients (with 18 warts) and 10 patients (with 20 warts) respectively did not fully comply with the protocol. At the start the number of warts per patient, their size, protruberance and localization were registered. Statistical analysis was performed by chi 2 test (unpaired case) in an intention to treat approach and of compliers only. OUTCOME MEASURES: Disappearance of warts, pain (on a 3-point scale), wounds, depigmentation. Non-compliers were asked by telephone if their warts had been cured. RESULTS: Of all patients 58% was cured by liquid nitrogen and 28% by Histofreezer (p = 0.01). Among the compliers these percentages were 67% and 35% of the patients (p = 0.01) and 66% and 49% of the warts (p = 0.08). The treatments were about equally effective in dorsal non protuberant and small (less than 5 mm) warts, and among young (less than 20 years) patients. CONCLUSION: The overall results of liquid nitrogen were better. The Histofreezer seems to be attractive in certain cases (e.g. children), but this should be the subject of further study.