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Community-Acquired Skin Infections in the Age of Methicillin-Resistant Organisms

Table 8. Time to resolution of infection (days), univariate analyses retrospective information
N =263

 

N

Time to Resolution
(Days)
Mean ± s.d.

ANOVA
P-Value

Gender

Female

131

10.8 ± 6.3 

Male

132

12.9 ± 8.6

0.028

 

   

Age group (years)

< 20

60

10.8 ± 4.5 

20 to < 40

66

11.4 ± 6.2 

40 to < 65

88

12.6 ± 10.1 

65 to 96

48

12.4 ± 7.1

0.467

 

   

Age group (years)

< 40

126

11.2 ± 5.5 

40 and older

136

12.6 ± 9.1

0.129

 

   

Total number of antibiotics used over course of infection

0

15

8.3 ± 5.9 

1

176

9.6 ± 3.7 

2

50

16.0 ± 10.3 

3

16

21.1 ± 10.0 

4

3

22.7 ± 12.6 

5

3

30.7 ± 14.6

< 0.001

 

   

Total number of antibiotics used

< 2

241

10.9 ± 6.4 

> 2

22

22.6 ± 10.9

< 0.001

 

   

Classification of infection

Abscess only

 94

10.6 ± 6.1

 

Cellulitis only

141

12.3 ± 8.2 

Abscess & cellulitis

28

13.7 ± 8.6

.088

 

   

Rurality of subject

Non-rural

183

10.7 ± 6.3 

Rural

80

14.6 ± 9.0

< 0.001

 

   

Face/neck

34

13.5 ± 10.7 

Groin/pubic/lower extremities

122

13.4 ± 8.5 

Thorax/upper extremities

104

9.6 ± 4.1

< 0.001

 

 

 

 

Subject hospitalized

Yes

 11

21.6 ± 14.9 

No

252

11.4 ± 6.8

< 0.001

 

   

Initial temperature (°F) (not everyone had a temperature recorded)

< 99

206

11.5 ± 7.3 

99 and above

24

15.1 ± 10.0

0.031

 

   

Initial antibiotics given covered MRSA during infection (not everyone received an antibiotic)

Yes

70

11.4 ± 6.6 

No

176

12.3 ± 8.0

0.421

 

 

  

Antibiotics given covered MRSA at some point during infection (not everyone received an antibiotic)

Yes

 91

13.3 ± 8.3 

No

157

11.4 ± 7.1

0.064

 

   

Incision and drainage done

Yes

 85

10.2 ± 5.6 

No

178

12.7 ± 8.3

0.014

 

   

Wound packed

Packed

30

 9.8 ± 6.9 

Not packed

55

10.5 ± 4.8 

Incision and drainage not done

178

12.7 ± 8.3

0.046

 

   

Only for those (n = 85) who had incision and drainage

Wound packed

30

 9.6 ± 6.9 

Wound not packed

55

10.5 ± 4.8

0.592

 

   

MRSA identified vs. others

 

 

 

MRSA identified

45

13.3 ± 6.2 

All others

218

11.6 ± 7.8

0.160

 

   

Patient risk factors (at least one of 13 risk factors)

  

 

At least one of risk factors

 69

13.8 ± 8.9 

No risk factors

194

11.2± 6.9

0.016

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Table 9. Time to resolution using cox proportional hazards regression for retrospective data
N=260 cases, controlling for clinic-level clustering

Patient Characteristics

VariableHazard Ratio* P-Value

Male (vs. female)

0.831<.0001

Rural (vs. urban)

0.657.0009

At least one MRSA risk factor (vs. none)

0.782.0470

Infection Site (vs. thorax/upper extremity)

  

   Face/neck

0.549.0054

   Groin/pubic area/lower extremity

0.574<.0001

Patient and Clinical Characteristics

VariableHazard Ratio*P-Value

Age <40 yrs. (vs. ≥ 40 yrs.)

1.088N.S.

Male (vs. female)

0.838.0003

Rural (vs. urban)

0.718.0194

At least one MRSA risk factor (vs. none)

0.844.1427

Infection Site (vs. thorax/upper extremity)

  

Face/neck

0.548.0014

Groin/pubic area/lower extremity)

0.564<.0001

Total number of antibiotics prescribed over course of infection ≤2 (vs. >2)

2.797<.0001

Patient hospitalized (vs. not)

0.567.0135

MRSA identified (vs. not)

0.862.0633

†Controlled for age category
*Hazard ratio: a value less than 1 means the infection is less likely to resolve at any given time point with the factor present; a value greater than 1 means the infection is more likely to resolve with the factor present.

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Table 10. Prospective skin forms returned by clinic

IRENE Office (Office No.)

City

No. Prospective Skin
and Soft Tissue
Forms Returned

No. Prospective Skin
and Soft Tissue Forms
Used in Analysis

Family Medicine Associates (3)

Guttenberg

24

23

Genesis Family Medicine (1)

Davenport

10

8

Genesis Family Medicine (2)

Blue Grass

1

0

Manchester Family Medical Associates (4)

Manchester

9

9

Medical Associates (5)

Le Mars

11

11

The Country Doctor (6)

Bloomfield

0

0

University of Iowa Hospitals and Clinics CMS Riverside Clinic (7)

Riverside

7

5

University of Iowa Hospitals and Clinics CMS Sigourney Clinic (8)

Sigourney

12

10

University of Iowa Hospitals and Clinics Family Medicine Clinic (9)

Iowa City

30

30

Urbandale Family Physicians (10)

Urbandale

18

18

Total

 

122

114

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Table 11. Demographic information from prospective skin and soft tissue infection forms

Clinic

No. Useable Skin
and Soft Tissue Infection
Prospective Forms

Male
N (%)

Uninsured

Mean Age
Years

Rural County
N (%)

1

8

0

1 (4)

41

0

2

0

0

0

0

0

3

23

11 (48)

0

42

20 (91)

4

9

4 (44)

0

36

1 (11)

5

11

6 (55)

0

30

0

6

0

0

0

0

0

7

5

5 (100)

0

24

0

8

10

5 (50)

1 (9)

32

10 (100)

9

30

10 (33)

0

43

0

10

18

7 (39)

0

44

0

Total

114

48 (42)

2 (2)

39

31 (27)

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Current as of March 2011
Internet Citation: Community-Acquired Skin Infections in the Age of Methicillin-Resistant Organisms. March 2011. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/mrsa/iowa_mrsatabs8-11.html