Skin and soft tissue infection incidence before and during the COVID-19 pandemic

Abstract

Skin and Soft Tissue Infections (SSTIs) are common bacterial infections. We hypothesized that due to the COVID-19 pandemic, SSTI rates would significantly decrease due to directives to avoid unneeded care and attenuated SSTIs risk behaviours. We retrospectively examined all patients with an ICD-10 diagnosis code in the Los Angeles County Department of Health Services, the second largest U.S. safety net healthcare system between 16 March 2017 and 15 March 2022. We then compared pre-pandemic with intra-pandemic SSTI rates using an interrupted time series analysis. We found 72,118 SSTIs, 46,206 during the pre-pandemic period and 25,912 during the intra-pandemic period. Pre-pandemic SSTI rate was significantly higher than the intra-pandemic rate (3.27 vs. 2.31 cases per 1,000 empanelled patient-months, P < 0.0001). The monthly SSTI cases decreased by 1.19 SSTIs/1,000 empanelled patient-months between the pre- and intra-pandemic periods (P = 0.0003). SSTI subgroups (inpatient, observation unit, emergency department, and outpatient clinics), all had significant SSTI decreases between the two time periods (P < 0.05) except for observation unit (P = 0.50). Compared to the pre-COVID-19 pandemic period, medically attended SSTI rates in our large U.S. safety net healthcare system significantly decreased by nearly 30%. Whether findings reflect true SSTI decreases or decreased health system utilization for SSTIs requires further examination.

Keywords: COVID-19; skin infections; soft tissue infections.

Figure 1.

SSTI rates (SSTIs/1000 empaneled patient-months) for pre-pandemic and intra-pandemic periods are graphically represented. Immediately about the X-axis label, the horizontal dashed line pointing left indicates the pre-pandemic period and black solid line pointing right indicates the intra-pandemic period. The first set of vertical perpendicular dashed lines represent the interval period of the first Los Angeles County Department of Health Services (LAC DHS) “stay at home order”. The second set of vertical perpendicular dashed lines represent the interval period of the second (LAC DHS) “stay at home order”. The Gap between MAR20 (March 2020) and APR20 (April 2020) is the transition period between pre-pandemic and intra-pandemic, which we censored (see text). The asterisks below MAR17, MAR20, and MAR22 were used to indicate that we used only half months of data in order to keep the time periods at intervals of 1 calendar year (see text for details).