How to appraise a prognostic study.

Prognostic studies are studies that examine selected predictive variables or risk factors and assess their influence on the outcome of a disease. They allow clinicians to understand better the natural history of a disease, guide clinical decision-making by facilitating the selection of appropriate treatment options, and allow more accurate prediction of disease outcomes. Appraising prognostic studies involves determining the internal validity of the study design and evaluating the influence of systemic errors or bias. In studies examining multiple prognostic variables, care must be taken to minimize the confounding influence each variable would have on the other parameters. Evaluating the results of appropriate statistical analysis enables conclusions to be made that may influence clinical practice. Care must be taken to ensure that the conditions under which the prognostic study were conducted resemble circumstances in the local institution so as to allow the conclusions to be applied to local practices.

Laparoscopic appendectomy for perforated appendicitis.

Although laparoscopic appendectomy for uncomplicated appendicitis is feasible and safe, its application to perforated appendicitis is uncertain. A retrospective study of all patients with perforated appendicitis from 1992 to 1999 in a university hospital was performed. A series of 231 patients were diagnosed as having perforated appendicitis. Of these patients, 85 underwent laparoscopy (LA), among whom 40 (47%) required conversion to an open procedure. An open appendectomy (OA) was performed in 146 patients. The operating time was similar for the two groups. Return of fluid and solid diet intake were faster in LA than OA patients (p < 0.01). Postoperative infections including wound infections and abdominal abscesses occurred in 14% of patients in the laparoscopy group and in 26% of those with OA (p < 0.05). The surgeon's experience correlated with the conversion rate. Laparoscopic appendectomy is associated with a high conversion rate for perforated appendicitis. If successful, it offers patients faster recovery and less risk of infectious complications.