Formula of Operative Risk Probability in the Gastroenterologic Surgery

Junichi Yoshida, Kazuhiro Otani, Naoki Otomo, Kouhei Akazawa*, Kazuo Chijiiwa, Masao Tanaka

Department of Surgery I and *Medical Informatics, Kyushu University Faculty of Medicine

We elaborate the formula of operative risk probability in gastroenterlogic surgery to quantify operative risks. Subjects were 121 patients who underwent operations for gastroenterologic diseases. Background factors were American Society of Anesthesiologists'status [ASAS], age, sex, body weight, modified Oxford score, steroid administered, and respiratory index. Resultant factors were postoperative complications. Logistic regression analysis was used to induce the risk score (u) of significant factors, with which the probability of operative risk, P, was formulated: P=exp(u)/[1 + exp(u)]. The results yielded a linear combination for overall complications (n=46): u=0.8667×(ASAS) + 0.0043×(operative time) + 2.626×(wound) - 8.950. P for patients with complications was 0.51±0.25 whereas p for those without (n=75) was 0.30±0.17. A cutpoint (P=0.62) best distinguished the presence or absence of complications. ASAS stood out as a significant factor common to various degrees of complications. The formula allows evaluation of the operative risks immediately after operations, thus providing means to facilitate postoperative management.

Key words
surgical risk, risk probability, respiratory index, logistic regression analysis

Reprint requests
Junichi Yoshida Department of Surgery I, Kuyshu University Faculty of Medicine
3-1-1 Maidashi, Higashi-ku, Fukuoka, 812 JAPAN

Accepted
June 8, 1994

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