Outcome of minimally invasive surgery. Qualitative analysis and evaluationof the clinical relevance of outcome variables by patients and physicians

Introduction: Mechanistic study endpoints, evaluated exclusively by the phy sician, are mostly used in clinical studies evaluating new treatment modali ties (e.g. laparoscopic cholecystectomy). Those endpoints often lack clinic al relevance. The patient's opinion concerning the importance of a study en dpoint is particularly important in the evaluation of minimally invasive pr ocedures, which place special emphasis on patient comfort. Methods: In a fi rst step it was evaluated by meta-analysis, which clinical endpoints have b een used for comparison of laparoscopic and conventional cholecystectomy. F urthermore, using a qualitative analysis it was investigated how important the individual study endpoints are for patients and physicians. Ten patient s and five surgeons were questioned in a structured interview. Results: Of all outcome variables used world-wide, approximately one third were hermene utic study endpoints, depending on the quality of the study, but often the method of evaluation was insufficient. Only three of 215 endpoints (< 2%)we re quality of life scores, an integrated concept of outcome was missing com pletely. The qualitative analysis confirms the claimed difference between i solated and integrated evaluation of treatment goals. The importance of pos toperative death is underestimated by patients and physicians; postoperativ e pain is overestimated. Patients ranked the outcome variable "restoration of full physical fitness" as the most important study endpoint after avoida nce of complications and death. It is underestimated in isolated evaluation and has not been used in the world literature at all. Conclusion: The anal ysis of clinical relevance of study endpoints should be the first and not t he last step of studies to evaluate surgical technology. It cannot be based purely on intuition; it must make use of scientifically accepted technique s (e.g. qualitative analysis).