Protocol design and current status of CLIVIT: a randomized controlled multicenter relevance trial comparing clips versus ligatures in thyroid surgery

BACKGROUND

Annually, more than 90000 surgical procedures of the thyroid gland are performed in Germany. Strategies aimed at reducing the duration of the surgical procedure are relevant to patients and the health care system especially in the context of reducing costs. However, new techniques for quick and safe hemostasis have to be tested in clinically relevance randomized controlled trials before a general recommendation can be given. The current standard for occlusion of blood vessels in thyroid surgery is ligatures. Vascular clips may be a safe alternative but have not been investigated in a large RCT.

METHODS/DESIGN

CLIVIT (Clips versus Ligatures in Thyroid Surgery) is an investigator initiated, multicenter, patient-blinded, two-group parallel relevance randomized controlled trial designed by the Study Center of the German Surgical Society. Patients scheduled for elective resection of at least two third of the gland for benign thyroid disease are eligible for participation. After surgical exploration patients are randomized intraoperatively into either the conventional ligature group, or into the clip group. The primary objective is to test for a relevant reduction in operating time (at least 15 min) when using the clip technique. Since April 2004, 121 of the totally required 420 patients were randomized in five centers.

DISCUSSION

As in all trials the different forms of bias have to be considered, and as in this case, a surgical trial, the role of surgical expertise plays a key role, and will be documented and analyzed separately. This is the first randomized controlled multicenter relevance trial to compare different vessel occlusion techniques in thyroid surgery with adequate power and other detailed information about the design as well as framework. If significant, the results might be generalized and may change the current surgical practice.

Methodological aspects of the evaluation of postoperative cancer surveillance. Part I: Validity

This contribution deals with problems of determining the validity and efficacy of diagnostic procedures used in postoperative cancer surveillance. While there is a large number of follow-up studies attempting to estimate sensitivity, specificity, or the predictive values of follow-up tests, the methodological aspects of validation are rarely addressed adequately in these publications, and the estimations of validity are often not well-founded. In the first part of this paper we analyze aspects of validity and validation studies. In particular, the following problems are addressed: a) Validity depends on the context; in particular, it depends on the characteristics of the population, the embedding of the test in a diagnostic strategy, the uncertainty of the test itself, the gold standard, and the criterion for positive test results. b) Global, time-independent measures of validity are hardly adequate. In particular, any attempt to incorporate a positive lead-time in the definition of the sensitivity is incompatible with an exhaustive classification matrix and with a meaningful definition of predictive values. c) Published estimations of sensitivity mostly suffer from numerous biases. First, there is work-up bias, which arises if positive and negative test-results are verified in a different way (in fact, this implies the use of two different gold standards). Next, test-review bias may occur unless the determination of the test result and the gold standard are mutually blinded. Finally, in quantitative tests, like tumor markers, there is a risk of resubstitution bias if the sample used for defining the cutoff level is identical to the validation sample. Several practical recommendations are given for designing validation studies. In the second part, problems of the efficacy of follow-up programs in regard to patient survival are discussed. Five necessary conditions must be satisfied in order to make such an effect possible. Taking these aspects into account, it can be shown that the usual arguments advanced in favor of diagnostic monitoring are not stringent. As for the design of studies on the efficacy of cancer surveillance, non-randomized studies are inconclusive given that they suffer from a variety of specific biases. It can be shown that the demand, often found in recent publications, that comparative studies of more versus less intensive monitoring be designed so as to permit the detection of a survival advantage in the subgroup of patients who relapse, is unjustified. In the final sections, an overview over published randomized studies and meta-analyses on the efficacy of postoperative monitoring of breast and colorectal cancer is given.

[Prehospital emergencies (emergencies and acute cases) in childhood]

OBJECTIVE

To determine incidence and management of prehospital emergencies in children.

METHODS

Between November 15, 1994 and March 14, 1995 in the City of Mainz (200,000 inhabitants) children with the diagnosis of a prehospital emergency were identified.

RESULTS

390 children were discovered, 62% in the age group 0-3 years. 85% of the emergency conditions occurred at home. In 71% the medical practitioner providing prehospital care was a paediatrician, in 14% an emergency physician. 48% of the children were transported to the Children's Hospital by the parents. 32 different types of emergency were diagnosed, 8 types more than 10 times. A retrospective analysis of 386 emergencies demonstrated an acute life-threatening situation in 12%. Lacking a final diagnosis in 19%, first and final diagnosis were identical in 64% of all children evaluated.

CONCLUSIONS

In Germany acute life-threatening emergencies are rare. Paediatricians are mainly involved also in the care of children with emergency conditions. Most pediatricians and nonpaediatricians are familiar with the relevant prehospital emergency conditions in the young children mainly concerned.