Page 200 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Chapter 9
using published classi cations. Of speci c interest for abdominal wall surgery is postoperative seroma. The seroma classi cation proposed by Morales-Conde is recommended(28).
The method of follow-up
The method for assessment of the primary and other endpoints of the study should be described clearly in the manuscript. Indeed, the recurrence rate measured will be in uenced by the method of follow-up. Figure 2 illustrates an increase in quality of follow-up which can range from the number of reoperations for recurrences seen to systematic investigation with medical imaging. The Palermo consensus group considered that follow-up without clinical examination of the patient is likely to give an important underestimation of the true recurrence rate and thus should be avoided. For other endpoints such as quality of life assessment, a follow-up by phone or mail might be adequate.
For large registries like the Danish Hernia Database, the Swedish Hernia Registry and the Herniamed database a clinical follow-up of all patients is not practical and achievable(29, 30). In the population based Danish Ventral Hernia Database the reoperation rate for recurrence is the primary outcome measurement as a “surrogate for recurrence”. Helgstrand et al.(31) demonstrated using a questionnaire and subsequent selective request for clinical follow-up, that the reoperation rate underestimated the overall risk for recurrence by four- to vefold. In the Herniamed registry patients are followed up using a questionnaire send to the patient at one, ve and ten years(29). Patients reporting a problem are invited for an examination by a physician.
Blinding of the patient and the evaluator at the primary endpoint to the treatment group in an interventional study has some organisational and logistic di culties, but should be considered when writing a study protocol because of the enhancement of the quality of the outcome data and the diminished risk of patient or investigator bias.
Ethical and nancial considerations
Studies should be performed according to the guidelines of the International Conference on Harmonisation (ICH) of Good Clinical Practice (GCP)(18). This includes the approval by the ethical committee of the center where the study is performed. Informed consent of the patients to be included in the study is mandatory.
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