1. Age and its Impact on Outcomes with Intraabdominal Infections
Drew Farmer, Jeffrey M. Tessier, James M. Sanders, Robert G. Sawyer, Billy J. Moore, Therese M. Duane
Baylor University Medical Center; Dallas, TX
JPS Health Network; Fort Worth, TX
Departments of Surgery and Public Health Sciences, University of Virginia; Charlottesville, VA

2. Introduction
Study to Optimize Peritoneal Infection Therapy (STOP-IT) trial
Prospective, multicenter, randomized controlled trial
Source control with short vs. longer abx therapy
No difference in outcomes
Age plays a significant role in the etiology of cIAIs
Correlation between age and outcomes after therapy was not investigated

3. Purpose
To determine if patients 65 years and older with complicated intraabdominal infection have different outcomes compared with their younger counterparts when treated with similar regimens

4. Methods Post-hoc analysis of the STOP-IT trial database
Patients were stratified by age <65 or ≥65 years of age.
Characteristics of the groups were analyzed including
clinical indicators of disease severity
infection acquisition location
site of the infection

5. Methods Subgroup analyses with focus on sites of infection
source control procedures
antimicrobial therapy
Primary outcomes:
surgical site infection (SSI)
recurrent intraabdominal infection (recIAI)
Death
composite of all three
Multivariate analysis was performed to identify independent predictors of outcomes

7. Results Table 1. Baseline characteristics stratified by age
Age < 65 Years (N=398)
Age ≥ 65 Years (N=120)
P-valueb
Gender, no. (%)
Male
217 (54.5)
72 (60.0)
0.30
Race, no. (%)
0.06
White
301 (75.6)
103 (85.8)
Black
80 (20.1)
14 (11.7)
Othera
17 (4.3)
3 (2.5)
Hispanic, no. (%)
29 (7.3)
6 (5.0)
0.38
Body Mass Index, mean±SD
29.4 ± 9.3
27.7 ± 7.0
0.03
APACHE II score, mean±SD
9.0 ± 5.8
13.4 ± 5.4
<0.0001

8. Results

9. Results
Table 2. Infection characteristics and treatment strategies stratified by age, N=518 
Characteristic
Age < (N=398)
Age ≥ (N=120)
P-value
Maximum white blood cell count, per mm3, mean±SD
16.7 ± 10.1
15.3 ± 7.5
0.09
Maximum body temperature, 0C, mean±SD
37.8 ± 0.9
37.5 ± 0.8
0.002
Setting of acquisition of cIAI, no. (%)
0.19
Community-acquired
240 (60.5)
81 (67.5)
Healthcare-associated
105 (26.5)
22 (18.3)
Hospital-acquired
52 (13.1)
17 (14.2)
Total antibiotic days, mean±SD
7.4 ± 5.7
7.5 ± 4.9
0.95

10. Results

11. Results

12. Results Site of Infection Source-control Procedure Colon or Rectum
Source-control Procedure
Site of Infection
Colon or Rectum
N=177
Small Intestine
N= 73
Appendix
Biliary Tree
N= 56
< 65
N= 119
> 65
N= 58
P-Valuea
N= 65
N= 8
P-Value1
N= 68
N= 5
N= 36
N= 20
Percutaneous drainage,
no. (%) 38
(31.9)
12 (20.7)
0.15
20 (30.8)
3 (37.5)
0.70 26
(38.2)
(0.0) 10
(27.8) 7
(35.0)
0.76
Resection and anastomosis or closure, no. (%) 29
(24.4) 18
(31.0)
0.37 17
(26.2) 2
(25.0)
1.00 19
(27.9) 1
(20.0) 12
(33.3) 6
(30.0)
Surgical drainage only, 28
(23.5)
(20.7)
0.71
(18.5)
0.64 14
(20.6)
(40.0)
0.30 9 4
0.75
Resection and proximal diversion,
(14.3) 11
(19.0)
0.51
(16.9)
(12.5)
(8.8)
0.09
(5.6)
0.53
Simple closure, no. (%)
(3.4) 5
(8.6)
0.16
(6.2)
(2.9)
(10.0)
0.61
Surgical drainage and diversion, no. (%) 3
(2.5)
0.55
(1.5)
(1.47)
(2.8)
(5.0)
Results

13. Results Site of Infection Antimicrobial Colon or Rectum N=177
Antimicrobial
Site of Infection
Colon or Rectum
N=177
Small Intestine
N= 73
Appendix
Biliary Tree
N= 56
< 65
N= 119
> 65
N= 58
P-Valuea
N= 65
N= 8
N= 68
N= 5
N= 36
N= 20 P-
Valuea
Amoxcillin or Amoxicillin-clavulanate,
no. (%) 6
(5.0) 2
(3.5)
1.00 4
(6.2) 1
(12.5)
0.45 9
(13.2)
(0.0)
(16.7) 5
(25.0)
0.50
Piperacillin-tazobactam, 61
(51.3) 36
(62.1)
0.27 30
(46.2)
(50.0) 21
(30.9)
(80.0)
0.04 28
(77.8) 13
(65.0)
0.35
Ertapenem, 17
(14.3)
(1.7)
0.01 7
(10.8)
(25)
0.25 11
(16.2)
(20.0)
(2.8)
Meropenem/
imipenem-cilastatin, 3
(5.2)
(1.5)
(8.3)
Ceftriaxone,
0.18
0.36
Cephamycinb,
(7.6)
0.17
(7.7)
0.51
(10.3)
0.55
Fluoroquinolonec, no. (%) 37
(31.1) 19
(32.8)
0.86 18
(27.7)
0.67 23
(33.8)
(40.0) 10
(27.8)
Metronidazole, 39
(31.0)
0.87
(32.3)
0.42 32
(47.1) 8
0.10
Vancomycin, 35
(29.4) 12
(18.5)
(37.5)
(8.8)
(22.2)
(30.0)
0.54
Results

14. Results
Of the primary outcomes only death was significantly different between the age groups
More prevalent in the ≥ 65 years group (3.3% vs. 0.3%, p=0.01)
No difference was seen in rates of
Surgical site infection (7.3% vs. 9.2%, p=0.50)
Recurrent intraabdominal infection (14.4% vs. 15.8%, p=0.69)
Composite outcome (20.4% vs. 26.7%, p=0.14)
Multivariate analyses did not reveal age as an independent predictor of the composite or individual outcomes

15. Discussion
Important to understand pathophysiology of intraabdominal infection in the elderly
Over 23% of the patients in the recently published STOP-IT trial were sixty-five years of age
Advanced age has previously been shown to be an independent risk factor for mortality in the patient with an IAI
SIS and IDSA guidelines list advanced age as a factor for predicting failure of source control
Recommend escalated antimicrobial therapy for empiric treatment of community acquired infections in this population
Vulnerable to the virulent effects of certain pathogens increasing their mortality rate

16. Discussion
Current recommendations suggesting a more aggressive approach to the treatment of the elderly make the findings in this study provocative
No statistical differences in prevalence of surgical site infections and recurrent intraabdominal infections between age groups
Groups had same duration of antimicrobial therapy and type of source control
Although more colorectal sources in ≥ 65 vs. more appendix and SB in < 65 the source control procedures were similar
Questionable whether there is need for a more aggressive approach as recommended by the SIS and IDSA

17. Discussion
These findings suggest that adherence to these guidelines was inconsistent, yet infection-specific differences in outcomes between the two groups were not statistically significant.

18. Limitations Post hoc analysis of prospectively collected data
Smaller sample size especially with subgroup analysis
Risk of Type II error

19. Conclusions
Despite distinct differences in etiology, this study confirms that a similar approach is important such that all patients should be expeditiously treated with source control and antibiotics.
Similar duration of therapy can be applied to the elderly population
Guidelines that recommend a different approach to patients with advanced age deserve further evaluation