Outcome of minimally invasive surgery. Qualitative analysis and evaluation of the clinical relevance of study variables by the patient and physician

INTRODUCTION: Mechanistic study endpoints, evaluated exclusively by the physician, are mostly used in clinical studies evaluating new treatment modalities (e.g. laparoscopic cholecystectomy). Those endpoints often lack clinical relevance. The patient's opinion concerning the importance of a study endpoint is particularly important in the evaluation of minimally invasive procedures, which place special emphasis on patient comfort. METHODS: In a first step it was evaluated by meta-analysis, which clinical endpoints have been used for comparison of laparoscopic and conventional cholecystectomy. Furthermore, using a qualitative analysis it was investigated how important the individual study endpoints are for patients and physicians. Ten patients and five surgeons were questioned in a structured interview. RESULTS: Of all outcome variables used world-wide, approximately one third were hermeneutic study endpoints, depending on the quality of the study, but often the method of evaluation was insufficient. Only three of 215 endpoints (< 2%) were quality of life scores, an integrated concept of outcome was missing completely. The qualitative analysis confirms the claimed difference between isolated and integrated evaluation of treatment goals. The importance of postoperative death is underestimated by patients and physicians; postoperative pain is overestimated. Patients ranked the outcome variable "restoration of full physical fitness" as the most important study endpoint after avoidance of complications and death. It is underestimated in isolated evaluation and has not been used in the world literature at all. CONCLUSION: The analysis of clinical relevance of study endpoints should be the first and not the last step of studies to evaluate surgical technology. It cannot be based purely on intuition; it must make use of scientifically accepted techniques (e.g. qualitative analysis).