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

Variable	Hazard 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†

Variable	Hazard Ratio*	P-Value
Age <40 yrs. (vs. ≥ 40 yrs.)	1.088	N.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