Development of machine learning models for the surveillance of colon surgical site infections

BACKGROUND

Conventional surgical site infection (SSI) surveillance is labour-intensive. We aimed to develop machine learning (ML) models for the surveillance of SSIs for colon surgery and to assess whether the ML could improve surveillance process efficiency.

METHODS

This study included cases who underwent colon surgery at a tertiary center between 2013 and 2014. Logistic regression and four ML algorithms including random forest (RF), gradient boosting (GB), and neural networks (NNs) with or without recursive feature elimination (RFE) were first trained on the entire cohort, and then re-trained on cases selected based on a previous rule-based algorithm. We assessed model performance based on the area under the curve (AUC), sensitivity, and positive predictive value (PPV). The estimated proportion of reduction in workload for chart review based on the ML models was evaluated and compared with the conventional method.

RESULTS

At a sensitivity of 95%, the NN with RFE using 29 variables had the best performance with an AUC of 0.963 and PPV of 21.1%. When combining both the rule-based algorithm and ML algorithms, the NN with RFE using 19 variables had a higher PPV (28.9%) than with the ML algorithm alone, which could decrease the number of cases requiring chart review by 83.9% compared with the conventional method.

CONCLUSION

We demonstrated that ML can improve the efficiency of SSI surveillance for colon surgery by decreasing the burden of chart review while providing high sensitivity. In particular, the hybrid approach of ML with a rule-based algorithm showed the best performance in terms of PPV.

Abstract P1-12-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Chung IY, Hur H, Lee J, Lee JW, Youn HJ, Han K, Kim NW, Jung S-Y, Kim Z, Kim KS, Lee MH, Han S-H, Jung SH. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-12-02.

Note: Double-layered polyimide film heater with low magnetic field generation

We designed a double-layered polyimide film heater where the direction of the injection current of each layer is opposite to that of the other layer to reduce the magnetic field. The width of the heater is 0.125 mm and the resistance is 21.2 Ω. This specially designed heater successfully demonstrated temperature controllability within 10 mK for an atomic cell in an atom spin gyroscope while minimizing the generation of the magnetic field to within 1 nT.

P2-16-14: Skin Sparing Mastectomy and Immediate Latissimus Dorsi Flap Reconstruction: Patient Reported Outcome and Factors Affecting the Highest Patient Satisfaction

Background: Skin sparing mastectomy (SSM) and immediate breast reconstruction (IBR) with latissimus dorsi (LD) flap is a tailored surgical procedure for breast cancer patients. In this study the oncologic safety, morbidities, and aesthetic results of SSM and LD IBR, as regards to patient satisfaction, were assessed.

Material and Methods: Between March 2000 and February 2011, single surgeon performed SSM and IBR for 145 patients. Eighty-five patients completed the patient satisfaction survey, and 65 patients with SSM and LD IBR were included. The patients were divided into 2 groups according to their degree of satisfaction, and a stratified analysis was performed.

Results: The mean age of the patients was 48.4 years (range, 21–74), and the pathologic results were infiltrating ductal carcinoma (n=48, 73.8%), ductal carcinoma in situ (n=15, 23.1%), and others (n=2, 3.1%). After a mean follow-up of 34 months (range, 1.6−89.9) no local recurrence occurred, and there were no skin necrosis or LD flap loss. Donor site morbidities were seroma (n=8, 12.3%), scarring (n=8, 12.3%), and back pain (n=6, 9.2%).

Decoupling a Cooper-pair box to enhance the lifetime to 0.2 ms

We present results on a circuit QED experiment in which a separate transmission line is used to address a quasilumped element superconducting microwave resonator which is in turn coupled to an Al/AlO(x)/Al Cooper-pair box charge qubit. With our device, we find a strong correlation between the lifetime of the qubit and the inverse of the coupling between the qubit and the transmission line. At the smallest coupling we measured, the lifetime of the Cooper-pair box was T₁=200 μs, which represents more than a twentyfold improvement in the lifetime of the Cooper-pair box compared with previous results. These results imply that the loss tangent in the AlO(x) junction barrier must be less than about 4×10⁻⁸ at 4.5 GHz, about 4 orders of magnitude less than reported in larger area Al/AlO(x)/Al tunnel junctions.

Contact investigations in congregate settings, New York City

SETTING

Large urban tuberculosis control program.

OBJECTIVE

To evaluate results of procedures implemented for systematic investigation of tuberculosis exposures in congregate settings.

DESIGN

Between October 1995 and December 2000, a unit consisting of epidemiologists, health educators and tuberculin screening staff investigated exposures in sites with >15 persons. Transmission at the site was defined as likely, possible, unlikely or unknown.

RESULTS

Among 100 investigations, 12 were tuberculosis case clusters, five were source case investigations, and 83 were exposures to single infectious cases. Transmission was likely in 24 (21%), possible in eight (8%), unlikely in 62 (62%), and could not be assessed in four (4%). Among the 83 exposures to single infectious cases, 2740 contacts were tested; 502 (18%) were infected. Among 1202 close contacts, 996 (82%) were tested, 197 (20%) were infected and started treatment of latent tuberculosis infection (LTBI) and 102/197 (52%) completed treatment. Sites with likely transmission had index patients with longer duration of cough (13 vs. 6 weeks, P = 0.01) and cavitary lesions (84% vs. 44%, P = 0.01) compared to sites with unlikely transmission.

CONCLUSION

A systematic approach for conducting contact investigations in congregate settings is useful for assessing transmission. As such investigations are resource intensive and transmission is not common, performing tuberculin skin testing after most persons would have converted should be considered in low-risk groups. Additional efforts are needed to increase completion of treatment for LTBI in contacts identified in these settings.

Immunosuppression and chemotherapeutic agents

There are numerous immunosuppressive agents which can be divided into two major categories, specific and non-specific immunosuppressants including cytotoxic agents derived from cancer chemotherapeutics. Whenever chemotherapeutic agents which cause unintentional immunosuppression are indicated in malignancy, combination treatment with immunotherapy (immunostimulation) is encouraged.

Inflammatory reactions and chemotactic factors

Inflammatory reactions are mediated by a large number of chemical substances called chemical mediators, including chemotactic factors, which are released by immunologic as well as non-immunologic mechanisms. Chemotactic factors which act indirectly on target tissue can not only enhance inflammatory reactions (NCF-C) but may also eliminate the reactions (ECF-A).

Hageman complement and factor

Complement components are activated by immunologic and non-immunologic mechanisms through various plasma protein systems such as immunoglobulins, properdin, plasmin, thrombin and Hageman factor. The activation of Hageman factor, followed by complement cleavage leading to liberation of various chemical mediators, can be initiated by exposure of negatively charged tissue components due to trauma and infection.