A Retrospective Analysis of the Incidence of Skin and Soft Tissue Infections Compared to Non-COVID-19 Conditions Before and During the Covid-19 Pandemic at A Large Safety Net Hospital System

Background: Skin and soft tissue infections (SSTIs) are among the most common infections encountered in U.S. healthcare settings. The COVID-19 pandemic substantially altered healthcare utilization patterns, with declines reported for several non-COVID conditions. We evaluated whether pandemic-associated changes in medically attended SSTI rates differed from those observed for other comparator urgent conditions (injury/trauma, myocardial infarction (MI), and stroke) in a large U.S. safety-net health system.

Methods: We conducted a retrospective health system–wide study using electronic health record data from the Los Angeles County Department of Health Services between 3/16/17and 3/15/22. The pre-pandemic period was defined as 3/16/17–3/15/20 and the intra-pandemic period as 4/1/20–3/15/22. SSTIs and comparator conditions were identified using ICD-10 codes. Changes in incidence rates and differences-in-differences between SSTIs and comparator conditions were analyzed using a three-way interaction Poisson regression model incorporating disease type, time period, and continuous time; additional models adjusted for seasonality.

Results: We identified 55,895 SSTI patients, 16,011 with MI, 255,897 with injury/trauma, and 10,597 with stroke. Mean ages were 46.8, 62.7, 39.0, and 58.4 years, respectively, and most patients were male (56–65%) and Hispanic/Latino (53–63%). Overall rates declined between the pre-pandemic and intra-pandemic periods for SSTIs (29%), injury/trauma (49%), and stroke (17%), while MI rates increased by 25%. In regression analyses, SSTI incidence significantly decreased during the intra-pandemic period (rate ratio 0.9943/1000 patient-months; 95% CI 0.9899–0.9987; P=0.01). Injury/trauma decreased more substantially (rate ratio 0.9798; 95% CI 0.9778–0.9819; P<0.0001), whereas stroke and MI showed no significant changes. Differences-in-differences analyses demonstrated a greater decline in injury/trauma compared with SSTIs (rate ratio 1.0147; 95% CI 1.0098–1.0197; P<0.0001), while changes in MI and stroke were not significantly different from SSTIs. Inpatient-only analyses showed unchanged SSTI hospitalization rates but significant declines in injury/trauma hospitalizations. Seasonally adjusted models produced similar findings, confirming that trauma/injury declined more than SSTIs, whereas MI and stroke trends did not significantly differ from SSTIs.

Conclusions: During the COVID-19 pandemic, rates of SSTIs and trauma/injuries both decreased, with trauma/injuries decreasing more than SSTIs. Despite observed significant decreases in SSTIs, there were no differences in rate pandemic changes between SSTIs and either MIs or strokes. Our findings shed insight into anticipated health services changes in common medical conditions that may be seen in future pandemics.