Incidence of Lower Extremity Cellulitis and Effects of ...
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Incidence of Lower Extremity Cellulitis and Effects of Seasonality After the Emergence of Community-Acquired Methicillin-Resistant Staphylococcus Aureus: A Population-Based Study Jasmine R Marcelin 1 , Douglas W Challener 2 , Eugene M Tan 1 , Brian Lahr 3 , Larry M Baddour 1 1 Division of Infectious Diseases, Department of Medicine, 2 Department of Internal Medicine, and 3 Division of Biomedical Statistics and Informatics Mayo Clinic, Rochester, MN © 2016 Mayo Foundation for Medical Education and Research Discussion/Conclusions • The incidence of LE cellulitis in Olmsted County was lower in 2013, as compared to the incidence reported in 1999 prior to the emergence of CA-MRSA. • The incidence of LEC in females in 2013 was lower than in 1999. • This suggests that CA-MRSA does not play a significant role in the epidemiology of LE cellulitis. • Prescribing practices should reflect this trend, avoiding first-line use of antibiotics targeting CA-MRSA in the absence of purulence. • Cases of LEC were seasonally distributed, with more cases occurring in spring/summer months. • A reanalysis of risk factor modification is needed. References 1. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft-tissue infections. Clin Infect Dis. 2005;41(10):1373-1406. 2. Swartz MN. Clinical practice. Cellulitis. N Engl J Med. 2004;350(9):904-912. 3. Ellis Simonsen SM, van Orman ER, Hatch BE, et al. Cellulitis incidence in a defined population. Epidemiology & Infection. 2006;134(2):293-299. 4. McCormic ZD, Balihe MN, Havas KA. Bacterial skin infections, active component, U.S. Armed Forces, 2000-2012. Med Surveill Monthly Rep (MSMR). 2013;20(12):2-7. 5. McNamara DR, Tleyjeh IM, Berbari EF, et al. Incidence of lower-extremity cellulitis: a population-based study in Olmsted county, Minnesota. Mayo Clin Proc. 2007;82(7):817-821. Table 1 Baseline Characteristics of Patients with Incident Cases of Confirmed LE Cellulitis (n=196) Characteristic No. (%) or mean (SD), or median [IQR] Age 61.2 [45-73.1] Male Sex 114 (58.2%) Caucasian Race 189 (96.4%) BMI 32.6 [26-38.1] Presenting Signs/Symptoms Erythema Warmth Tenderness Edema Pain 196 (100%) 143 (73%) 101 (51.5%) 162 (82.7%) 140 (71.4%) Presenting Anatomical Site Toe Foot Ankle Tibial Knee Femoral Multiple LE Nos 23 (11.7%) 34 (17.3%) 12 (6.1%) 51 (26%) 10 (5.1%) 8 (4.1%) 19 (9.7%) 39 (19.9%) Affected Side Left Right Both 92 (46.9%) 97 (49.5%) 7 (3.6%) Diagnosis Location Inpatient Outpatient Emergency Department 4 (2%) 132 (67.3%) 60 (30.6%) Duration of symptoms (days) 2 [1-5] Temperature at diagnosis 36.7 [36.4-37] Fever documented? 11 (7.4%) Required hospitalization 28 (14.3%) Length of hospitalization (days) 3.5 [2-6.5] Antibiotics prescribed 196 (100%) Duration of antibiotics (days) 10 [9-10] Previous history of cellulitis 46 (23.5%) Labs completed WBC at Diagnosis (51 done) 52 (26.5%) 10.5 [7.4-14.3] Background Lower extremity cellulitis (LEC) is common: • Population-based incidence of LEC in Olmsted County (OC), MN was 199 per 100,000 persons in 1999. • First description of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in 1999. • Not known whether CA-MRSA has affected the incidence of LEC. • Some empiric treatment recommendations include coverage for this organism. • Effects of seasonality on incidence of infectious diseases have been described for other entities. • Scant published data report the effect of seasonality on the incidence of LEC. Methods • Retrospective, population-based study among adults with LEC living in OC in 2013. • Patients selected for chart review based ICD-9 codes for first episode of LEC in the year 2013. • LEC defined as acute onset of warmth, erythema, and edema on the lower extremities, with or without fever or pain. Patients with purulent skin/soft tissue infections were excluded. • Medical records initially reviewed by trained nurse abstractors. JRM re-reviewed cases to confirm that they meet the case definition. LMB independently randomly reviewed 5% (93) of all charts; agreement was 96% on chart classification. • Poisson regression used to assess the influence of age, sex and seasonal effects on incidence. Objectives Using contemporary population-based cohort: • To determine the incidence of LEC since the emergence of CA-MRSA. • To determine effect of seasonality on LEC. Figure 1 Relationship of Age and Sex with Incidence of Lower Extremity Cellulitis in Olmsted County (2013) Note: Incidence data specifying counts of LEC cases (numerator) and counts of total at-risk adults (denominator) were organized strata specific to sex and each single year of age (18-100 years). Using this granular form of data, smoothing techniques (loess algorithm) were used to estimate incidence in relation to age and sex. Symbols represent sex-specific incidence rates estimated according to age groups (those shown in Table) to provide a crude verification of the smoothed trends. In a multivariable Poisson regression model, rates of incidence were higher in males and increased with age for both sexes (P<001 for both age and sex effects). Table 2 Incidence of Lower Extremity Cellulitis in Olmsted County, Minnesota (2013) by Age and Sex Groupings Females Males Both Sexes Age No. cases (unadjusted incidence rate, per 100,000 persons) 18-39 40-49 50-59 60-69 70-79 80-99 All Ages 18 (71.3) 6 (63.1) 19 (164.5) 10 (133.3) 12 (265.5) 17 (487.4) 82 (132.6) 21 (95.3) 12 (135.0) 19 (184.2) 30 (458.4) 13 (343.2) 18 (802.1) 113 (210.0) 39 (82.5) 18 (97.8) 38 (173.8) 40 (284.7) 25 (300.9) 35 (610.6) 195 (168.6) Overall Adjusted incidence rate (95% CI), per 100,000 persons Adjusting Population 2000 U.S. Whites 2000 U.S. Whites 128.7 (100.0, 157.4) 133.3 (104.1, 162.5) 214.8 (174.5, 255.2) 225.8 (183.5, 268.0) 168.2 (144.0, 192.4) 176.6 (151.5, 201.7) Note: Age-stratified results are reported as number of cases and rate of incidence (IR) in parentheses, while overall results appear as IR and 95% confidence interval (CI) adjusted for age and sex (or for age alone with gender-specific rates) by direct standardization against the U.S. White populations in 2000 and 2010; all incidence estimates assume an at-risk population of adults (age >18 years). Figure 2 Seasonal Variation in Incidence of Lower Extremity Cellulitis in Olmsted County (2013) Note: Smoothing techniques (loess algorithm) were used to estimate total and gender-specific incidence rates in relation to calendar year. Symbols represent gender-specific incidence rates estimated according to age groups (those shown in Table) to provide a crude verification of the smoothed trends. In a multivariable Poisson regression model adjusting for the effects of age and gender, the pre-specified interval of May-September (representing warm weather months) reflected significantly higher incidence compared to the remaining months of October-April (P=0.001). Table 3 Incidence of Lower Extremity Cellulitis in Olmsted County, Minnesota (2013) by Seasonal Periods LEC Cases Group Entire Year † Cold Months ‡ Adjusted incidence rate (95% CI), per 100,000 persons Female 133.3 (104.1, 162.5) 193.8 (139.5, 248.1) 90.1 (58.5, 121.7) Male 225.8 (183.5, 268.0) 260.3 (189.9, 330.7) 201.1 (149.0, 253.1) Total 176.6 (151.5, 201.7) 224.6 (180.9, 268.4) 142.3 (112.8, 171.9) Note: Gender-specific incidence rates are adjusted for age, While total incidence rates (bolded are adjusted for age and gender by direct standardization against the U.S. White population in 2010; all incidence estimates assume and at-risk population of adults (age >18 years). † Pre-specified interval of May-September was used to represent warm seasonal months ‡ Remaining months of October-April were considered to be cold seasonal months 10 100 1000 20 40 60 80 100 Age (years) Total incidence Male incidence Female incidence Incidence (per 100,000) 0 100 200 300 400 500 Month Incidence (per 100,000) Counts by month Total cases 14 11 16 19 26 14 23 20 21 11 6 14 Male cases 7 6 13 12 12 5 13 11 13 8 4 9 Female cases 7 5 3 7 14 9 10 9 8 3 2 5 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total incidence Male incidence Female incidence
Transcript of Incidence of Lower Extremity Cellulitis and Effects of ...
Incidence of Lower Extremity Cellulitis and Effects of Seasonality After the Emergence of Community-Acquired Methicillin-Resistant Staphylococcus Aureus:
A Population-Based StudyJasmine R Marcelin1, Douglas W Challener2, Eugene M Tan1, Brian Lahr3, Larry M Baddour1
1Division of Infectious Diseases, Department of Medicine, 2Department of Internal Medicine, and 3Division of Biomedical Statistics and InformaticsMayo Clinic, Rochester, MN
© 2016 Mayo Foundation for Medical Education and Research
Discussion/Conclusions• The incidence of LE cellulitis in Olmsted County
was lower in 2013, as compared to the incidence reported in 1999 prior to the emergence of CA-MRSA.
• The incidence of LEC in females in 2013 was lower than in 1999.
• This suggests that CA-MRSA does not play a signifi cant role in the epidemiology of LE cellulitis.
• Prescribing practices should refl ect this trend, avoiding fi rst-line use of antibiotics targeting CA-MRSA in the absence of purulence.
• Cases of LEC were seasonally distributed, with more cases occurring in spring/summer months.
• A reanalysis of risk factor modifi cation is needed.
References1. Stevens DL, Bisno AL, Chambers HF, et al. Practice
guidelines for the diagnosis and management of skin and soft-tissue infections. Clin Infect Dis. 2005;41(10):1373-1406.
2. Swartz MN. Clinical practice. Cellulitis. N Engl J Med. 2004;350(9):904-912.
3. Ellis Simonsen SM, van Orman ER, Hatch BE, et al. Cellulitis incidence in a defi ned population. Epidemiology & Infection. 2006;134(2):293-299.
4. McCormic ZD, Balihe MN, Havas KA. Bacterial skin infections, active component, U.S. Armed Forces, 2000-2012. Med Surveill Monthly Rep (MSMR). 2013;20(12):2-7.
5. McNamara DR, Tleyjeh IM, Berbari EF, et al. Incidence of lower-extremity cellulitis: a population-based study in Olmsted county, Minnesota. Mayo Clin Proc. 2007;82(7):817-821.
Table 1
Baseline Characteristics of Patients with Incident Cases of Confi rmed LE Cellulitis (n=196)
Characteristic No. (%) or mean (SD), or median [IQR]
Age 61.2 [45-73.1]
Male Sex 114 (58.2%)
Caucasian Race 189 (96.4%)
BMI 32.6 [26-38.1]
Presenting Signs/SymptomsErythemaWarmthTendernessEdemaPain
196 (100%)143 (73%)
101 (51.5%)162 (82.7%)140 (71.4%)
Presenting Anatomical SiteToeFootAnkleTibialKneeFemoralMultipleLE Nos
23 (11.7%)34 (17.3%)12 (6.1%)51 (26%)10 (5.1%)8 (4.1%)
19 (9.7%)39 (19.9%)
Affected SideLeftRightBoth
92 (46.9%)97 (49.5%)
7 (3.6%)
Diagnosis LocationInpatientOutpatientEmergency Department
4 (2%)
132 (67.3%)60 (30.6%)
Duration of symptoms (days) 2 [1-5]
Temperature at diagnosis 36.7 [36.4-37]
Fever documented? 11 (7.4%)
Required hospitalization 28 (14.3%)
Length of hospitalization (days) 3.5 [2-6.5]
Antibiotics prescribed 196 (100%)
Duration of antibiotics (days) 10 [9-10]
Previous history of cellulitis 46 (23.5%)
Labs completedWBC at Diagnosis (51 done)
52 (26.5%)10.5 [7.4-14.3]
Background
Lower extremity cellulitis (LEC) is common: • Population-based incidence of LEC in Olmsted County (OC), MN was 199
per 100,000 persons in 1999.
• First description of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in 1999.
• Not known whether CA-MRSA has affected the incidence of LEC.
• Some empiric treatment recommendations include coverage for this organism.
• Effects of seasonality on incidence of infectious diseases have been described for other entities.
• Scant published data report the effect of seasonality on the incidence of LEC.
Methods• Retrospective, population-based study among adults with LEC living in OC
in 2013.
• Patients selected for chart review based ICD-9 codes for fi rst episode of LEC in the year 2013.
• LEC defi ned as acute onset of warmth, erythema, and edema on the lower extremities, with or without fever or pain. Patients with purulent skin/soft tissue infections were excluded.
• Medical records initially reviewed by trained nurse abstractors. JRM re-reviewed cases to confi rm that they meet the case defi nition. LMB independently randomly reviewed 5% (93) of all charts; agreement was 96% on chart classifi cation.
• Poisson regression used to assess the infl uence of age, sex and seasonal effects on incidence.
Objectives
Using contemporary population-based cohort:• To determine the incidence of LEC since the emergence of CA-MRSA.
• To determine effect of seasonality on LEC.
Figure 1
Relationship of Age and Sex with Incidence of Lower Extremity Cellulitis in Olmsted County (2013)
Note: Incidence data specifying counts of LEC cases (numerator) and counts of total at-risk adults (denominator) were organized strata specifi c to sex and each single year of age (18-100 years). Using this granular form of data, smoothing techniques (loess algorithm) were used to estimate incidence in relation to age and sex. Symbols represent sex-specifi c incidence rates estimated according to age groups (those shown in Table) to provide a crude verifi cation of the smoothed trends. In a multivariable Poisson regression model, rates of incidence were higher in males and increased with age for both sexes (P<001 for both age and sex effects).
Table 2
Incidence of Lower Extremity Cellulitis in Olmsted County, Minnesota (2013) by Age and Sex
Groupings Females Males Both Sexes
Age No. cases (unadjusted incidence rate, per 100,000 persons)
18-3940-4950-5960-6970-7980-99All Ages
18 (71.3)6 (63.1)
19 (164.5)10 (133.3)12 (265.5)17 (487.4)82 (132.6)
21 (95.3)12 (135.0)19 (184.2)30 (458.4)13 (343.2)18 (802.1)
113 (210.0)
39 (82.5)18 (97.8)
38 (173.8)40 (284.7)25 (300.9)35 (610.6)
195 (168.6)
Overall Adjusted incidence rate (95% CI), per 100,000 persons
Adjusting Population2000 U.S. Whites2000 U.S. Whites
128.7 (100.0, 157.4)133.3 (104.1, 162.5)
214.8 (174.5, 255.2)225.8 (183.5, 268.0)
168.2 (144.0, 192.4)176.6 (151.5, 201.7)
Note: Age-stratifi ed results are reported as number of cases and rate of incidence (IR) in parentheses, while overall results appear as IR and 95% confi dence interval (CI) adjusted for age and sex (or for age alone with gender-specifi c rates) by direct standardization against the U.S. White populations in 2000 and 2010; all incidence estimates assume an at-risk population of adults (age >18 years).
Figure 2
Seasonal Variation in Incidence of Lower Extremity Cellulitis in Olmsted County (2013)
Note: Smoothing techniques (loess algorithm) were used to estimate total and gender-specifi c incidence rates in relation to calendar year. Symbols represent gender-specifi c incidence rates estimated according to age groups (those shown in Table) to provide a crude verifi cation of the smoothed trends. In a multivariable Poisson regression model adjusting for the effects of age and gender, the pre-specifi ed interval of May-September (representing warm weather months) refl ected signifi cantly higher incidence compared to the remaining months of October-April (P=0.001).
Table 3
Incidence of Lower Extremity Cellulitis in Olmsted County, Minnesota (2013) by Seasonal Periods
LEC Cases Group Entire Year† Cold Months‡
Adjusted incidence rate (95% CI), per 100,000 persons
Female 133.3 (104.1, 162.5) 193.8 (139.5, 248.1) 90.1 (58.5, 121.7)
Male 225.8 (183.5, 268.0) 260.3 (189.9, 330.7) 201.1 (149.0, 253.1)
Total 176.6 (151.5, 201.7) 224.6 (180.9, 268.4) 142.3 (112.8, 171.9)
Note: Gender-specifi c incidence rates are adjusted for age, While total incidence rates (bolded are adjusted for age and gender by direct standardization against the U.S. White population in 2010; all incidence estimates assume and at-risk population of adults (age >18 years).†Pre-specifi ed interval of May-September was used to represent warm seasonal months‡Remaining months of October-April were considered to be cold seasonal months
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Counts by monthTotal cases 14 11 16 19 26 14 23 20 21 11 6 14Male cases 7 6 13 12 12 5 13 11 13 8 4 9Female cases 7 5 3 7 14 9 10 9 8 3 2 5
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