Materials and methods
For both pediatric and adult populations, medical records were reviewed retrospectively of patients who had been treated for RRP with operating room procedures,in the period from January 2018 to April 2021. The inclusion criteria included patients with a diagnosis of RRP and at least 6 months of follow-up. Each patient signed an informed consent form before surgery. Patients were excluded if they did not fulfill these requirements, or if they had received tracheostomy.
The following patient demographic data were collected and analyzed: age, gender, smoking status, symptoms at the first procedure, length of follow-up time, localization of the papillomas, histological findings(evidence of dysplasia), number of surgical procedures, the type and date of the surgical treatment(Microdebrider, or CO2 laser or KTP laser), recurrence rate. The treatment intervals were calculated based upon these dates. Anatomical Derkay severity scores were captured for all patients preoperatively. The survival curves were plotted based on the recurrence events and follow-up time, through which we could compare the recurrence trends of patients used three different surgical modalities. According to Derkay et al, the aerodigestive tract is divided into 25 subsites with each given a score if disease is present (0 is no lesion, 1 is surface lesion, 2 is raised lesion, and 3 is bulk lesion).[11]
Treatment groups were stratified as microdebrider, CO2 laser and KTP laser. We analyzed AO-RRP and JO-RRP populations respectively, and we also combined the pediatric and adult data for comparison among three treatment modality groups.
The calculation of the interval of treatment is started at 00:00 on the first day after surgery, and ended at the time when the patient undergoes surgery again because of a recurrence of the lesion. How to determine whether a patient is the recurrent case or not? The surgeons recorded photographs or videos of hard laryngoscopy or electronic fiber laryngoscopy to compare preoperative and postoperative lesions. Criteria for judging recurrence: papillary lesion reappear in the same or adjacent parts of the previous operation, which is pathologically confirmed as papillomas after surgery. When the interval between surgeries is recorded, this case will be treated as a new case for re-entry follow-up after surgery. Those who had not relapsed at the end of the follow-up date were also counted separately as truncated data.
Statistics were performed using SPSS (IBM SPSS Statistics 26). Continuous variables with a normal distribution were compared using a 2-tailed t-test and/or analysis of variance. Continuous variables without a normal distribution were compared with Mann–Whitney test or Kruskal–Wallis test. Categorical variables were compared with either chi-squared test or Fisher’s exact. The survival curve were plotted in GraphPad Prism based on the recurrence events and follow-up time. A value of P<0.05 was considered statistically significant.