Predictive model of surgical infection to enhance patient safety: A retrospective cohort study

Gonzalez, Christiany Moçali; Freire, Joana de Oliveira Pantoja; de Cerqueira, Camila Medeiros dos Santos; Paes, Graciele Oroski

doi:10.1590/1980-220X-REEUSP-2025-0207en

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ORIGINAL ARTICLE • Rev. esc. enferm. USP 59 • 2025 • https://doi.org/10.1590/1980-220X-REEUSP-2025-0207en linkcopy

Predictive model of surgical infection to enhance patient safety: A retrospective cohort study

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Objective To identify risk factors for surgical site infection and to establish a prediction model.

Method Retrospective cohort study with 20,778 surgeries performed between 2009 and 2019 at a university hospital in Rio de Janeiro. Clinical and operative variables were analyzed using multivariate logistic regression (p≤0.05).

Results The overall surgical infection rate was 7.2%. Age ≥41 years presented an odds ratio between 1.52 and 3.77 (p < 0.0001). Contaminated and infected surgeries increased the risk threefold (95% CI: 2.48–3.63). Urgent procedures (OR = 2.04; 95% CI: 1.83–2.28) and ASA III (OR=3.77) were associated with a higher risk. Each additional hour of surgery increased the risk by 34% (OR = 1.34; 95% CI: 1.30–1.38). Conventional technique had a risk 2.7 times greater than videolaparoscopy (RC = 2.72; p < 0.0001).

Conclusion The developed model allows for precise stratification of surgical site infection risk and supports preventive strategies, improving the surveillance and management of surgical risk in highly complex hospitals.

DESCRIPTORS
Risk Assessment; Surgical Wound Infection; Patient Safety

Variables	N	%	Min-Max	Mean (±SD)
Sex
Male	8622	41.5
Female	12156	58.5
Age			18–97	52.0 (±16.3)
Age range
From 18 to 30 years old	2551	12.3
31 to 40 years	2746	13.2
41 to 50 years	3819	18.4
51 to 60 years	4875	23.5
61 to 70 years	4017	19.3
71 or older	2770	13.3
Duration in hours			0.083–23.3	2.5 (±1.6)
ASA
1	6273	30.2
2	10375	49.9
3	3818	18.4
4	305	1.5
5	6	0.0
Type of surgery
Elective	19390	93.3
Urgent	1388	6.7
Outcome
Death	634	3.1
Discharge	20144	96.9
Use of Video
No	17607	84.7
Yes	3171	15.3
Used implants
No	15714	75.6
Yes	5064	24.4

Variables	N	%
Occurrence of infection
Yes	1,491	7.18
No	19,287	92.82
Type of infection
Superficial	814	54.59
Intracavitary	470	31.52
Deep	207	13.88
Locations of infection diagnosis
Outpatient’s	808	54.19
Ward	683	45.81

Characteristics studied	Presence of infection				OR (95%CI)	p
	No		Yes
	n	%	n	%
Sex
Male	11300	93.0	856	7.0	1.05 (0.94–1.17)	0.374
Female	7987	92.6	635	7.4
Age range
From 18 to 30 years old	2442	95.7	109	4.3	1.0
31 to 40 years	2616	95.3	130	4.7	1.11 (0.86–1.45)	0.419
41 to 50 years	3576	93.6	243	6.4	1.52 (1.21–1.92)	<0.0001
51 to 60 years	4518	92.7	357	7.3	1.77 (1.42–2.21)	<0.0001
61 to 70 years	3655	91.0	362	9.0	2.22 (1.78–2.77)	<0.0001
71 or older	2480	89.5	290	10.5	2.62 (2.09–3.29)	<0.0001
Type of surgery
Urgent	1209	87.1	179	12.9	2.04 (1.73–2.41)	<0.0001
Elective	18078	93.2	1312	6.8	1.0
ASA
Classification 1	6045	96.4	2299	3.6	1.0
Classification 2	9629	92.8	746	7.2	2.04 (1.76–2.38)	<0.0001
Classification 3	3340	87.5	478	12.5	3.77 (3.20–4.44)	<0.0001
Contamination potential
Clean	11130	94.7	626	5.3	1.0
Potentially contaminated	5955	92.9	457	7.1	1.37 (1.21–1.55)	<0.0001
Contaminated	1726	84.2	323	15.8	3.33 (2.88–3.84)	<0.0001
Infected	476	84.8	85	15.2	3.18 (2.49–4.01)	<0.0001
Use of Video
No	16245	92.3	1362	7.7	1.98 (1.64–2.38)	<0.0001
Yes	3042	95.9	129	4.1	1.0
Use of implants
No	13379	92.1	1146	7.9	1.47 (1.30–1.66)	<0.0001
Yes	5908	94.5	345	5.5	1.0
Otorhinolaryngology
Yes	1017	95.9	43	4.1	0.53 (0.38–0.72)	<0.0001
No	18270	92.7	1448	7.3	1.0
Neurosurgery
Yes	1215	92.5	99	7.5	1.06 (0.86–1.31)	0.603
No	18072	92.8	1392	7.2	1.0
Urology
Yes	1255	93.7	85	6.3	0.87 (0.69–1.09)	0.122
No	18032	92.8	1406	7.2	1.0
Gynecology
Yes	1507	92.1	129	7.9	1.12 (0.93–1.35)	0.247
No	17780	92.9	1362	7.1	1.0
Plastic surgery
Yes	1684	96.6	60	3.4	0.44 (0.34–0.57)	<0.0001
No	17603	92.5	1431	7.5	1.0
Orthopedics and trauma
Yes	3329	95.8	147	4.2	0.52 (0.44–0.62)	<0.0001
No	15958	92.2	1344	7.8	1.0
General Surgery
Yes	7246	91.9	638	8.1	1.25 (1.12–1.38)	<0.0001
No	12041	93.4	853	6.6	1.0

	N	Average in hours (±SD)	Min-Max	Median	IQR 25%–75%	p*
Infection
Yes	1491	3.43 (1.96)	0.33–13.98	3.00	2.00–4.50	<0.0001
No	19287	2.38 (1.54)	0.08–23.25	2.00	1.25–3.00

	OR	95%CI	p
Model 1
Age (years)	1.01	1.01–1.02	<0.0001
Duration of procedure (hours)	1.34	1.30–1.38	<0.0001
Emergency surgery (vs. elective)	1.02	0.83–1.26	0.835
No video use (vs. with use of video)	2.73	2.23–3.36	<0.0001
Use of implants	1.05	0.91–1.21	0.537
Potentially contaminated (vs clean)	1.50	1.23–1.72	<0.0001
Contaminated (vs clean)	2.94	2.49–3.47	<0.0001
Infected (vs clean)	2.68	2.00–3.61	<0.0001
General surgery (vs. other medical services)	1.67	1.48–1.89	<0.0001
ASA 2 (vs. ASA 1)	1.45	1.23–1.72	<0.0001
ASA 3 (vs. ASA 1)	1.89	1.56–2.29	<0.0001
Model 2
Age (years)	1.01	1.00–1.01	<0.0001
Duration of procedure (hours)	1.34	1.30–1.38	<0.0001
No video use (vs. with use of video)	2.74	2.23–3.36	<0.0001
Use of implants	1.05	0.91–1.21	0.531
Potentially contaminated (vs clean)	1.50	1.30–1.72	<0.0001
Contaminated (vs clean)	2.95	2.50–3.58	<0.0001
Infected (vs clean)	1.68	1.49–1.89	<0.0001
General surgery (vs. other medical services)	1.68	1.49–1.89	<0.0001
ASA 2 (vs. ASA 1)	1.45	1.23–1.72	<0.0001
ASA 3 (vs. ASA 1)	1.90	1.57–2.29	<0.0001
Model 3
Age (years)	1.01	1.01–1.02	<0.0001
Duration of procedure (hours)	1.34	1.30–1.38	<0.0001
No video use (vs. with use of video)	2.72	2.22–3.34	<0.0001
Potentially contaminated (vs clean)	1.52	1.33–1.73	<0.0001
Contaminated (vs clean)	3.00	2.57–3.50	<0.0001
Infected (vs clean)	2.76	2.10–3.63	<0.0001
General surgery (vs. other medical services)	1.68	1.48–1.89	<0.0001
ASA 2 (vs. ASA 1)	1.46	1.24–1.72	<0.0001
ASA 3 (vs. ASA 1)	1.91	1.58–2.30	<0.0001

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Universidade de São Paulo, Escola de Enfermagem Av. Dr. Enéas de Carvalho Aguiar, 419 , 05403-000 São Paulo - SP/ Brasil, Tel./Fax: (55 11) 3061-7553, - São Paulo - SP - Brazil
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[T1FN1] Notes: SD = standard deviation; ASA = American Society of Anesthesiologists.