Background

Basic principles of clinical trials of nonpharmacologic treatment are similar to those of pharmacologic treatment, but its some special characteristics should be discussed.
Objective

To explore the design characteristics of clinical surgery trial through the example of tunnel thread-drawing therapy for simple anal fistula. Design, setting, participants and interventions: The clinical trial was designed as a prospective, controlled, randomized multicenter trial. The patients came from Longhua Hospital, Yueyang Hospital of Integrated Traditional Chinese and Western medicine, and Affiliated Hospital of Jianxi University of Traditional Chinese Medicine. Stratified random was performed according to the subtype of anal fistula including low and high anal fistula. Full analysis set was applied to analyze the baseline data, and per protocol set was used in efficacy and safety analysis. The intervention was tunnel thread-drawing method. Classical therapy of thread-drawing method was employed as positive control.Main outcome measures: The primary outcomes were course of recovery and cure rate. Quality of life score was used as secondary outcome and anal maximum constriction pressure was considered as safety outcome.
Results

Optimal efficiency testing method was used to estimate sample size. A total of 244 subjects were recruited and 236 subjects completed the trial. There was no significant difference in the cure rate of the low and high anal fistula between the treatment group and control group. There was a significant difference in the course of recovery in the patients with low and high anal fistula between treatment group and control group (P<0.01). To the patients with low anal fistula, the course of recovery in the treatment group was (22.26±8.67) d, and the course of recovery in the control group was (31.41±11.39) d. To the patients with high anal fistula, the course of recovery in the treatment group was (24.73±8.15) d, and the course of recovery in the control group was (32.20±12.60) d. There was no significant difference in the scores of quality of life in the patients with low anal fistula between the treatment group and control group (P>0.05). The trial showed that the tunnel thread-drawing therapy was significantly more effective than classical method for improving the anal sphincter function and patient satisfaction with treatment in the patients with high anal fistula. However the other items of quality of life in the two groups did not show significant difference. There was no any adverse event report in each group. There was no significant difference in the anal maximum constriction pressure in the treatment group before and after the operation.
Conclusion

The trial shows that the tunnel thread-drawing therapy for simple anal fistula can shorten the course of recovery and improve the patients’ quality of life. The training about surgical intervention and clinical implementation program is important in clinical surgery trial. Blind is absolutely difficult to implement and placebo cannot be used in this kind of trial.

Key words: Clinical protocols, Research design, Tunnel Thread-drawing method, Anal fistula, Surgical procedures, Operative, Prospective studies, Multicenter trials, Randomized controlled trials