Trends in Outpatient Medical-Care Seeking for Acute Gastroenteritis During the COVID-19 Pandemic,2020

Background

During the coronavirus disease 2019 (COVID-19) pandemic, the number of enteric infections reported by states to public health surveillance decreased sharply (Ray et al., 2021). In Colorado, the incidence of laboratory-confirmed infections caused by nine enteric pathogens was 30% lower in 2020 than in the previous 3-year average, and the number of reported norovirus outbreaks was 76% lower (J Queen, Personal Communication). Stay-at-home orders, restaurant closures, international travel restrictions, and other public health interventions likely reduced exposures commonly associated with enteric disease, as well as opportunities for disease transmission. Changes in medical care-seeking behavior and public health and laboratory capacity may have impacted the diagnosis of enteric infections.

Acute gastroenteritis (AGE) is a common syndrome of acute enteric infections. The purpose of this analysis was to evaluate trends in outpatient medical care-seeking behavior for AGE in Colorado during 2020 compared with that during the previous 3 years.

Materials and Methods

Outpatient encounter data were available from the Colorado Health Observation Regional Data Service (CHORDS) from 2017 to 2020. The methods and structure of CHORDS are described in detail elsewhere (Bacon et al., 2019). In brief, the CHORDS network is a collaborative regional data network that provides deidentified electronic health record (EHR) data from 14 contributing health care providers in 9 Colorado counties. CHORDS network providers are concentrated in the Denver Metropolitan Area, with EHR data covering ∼25% of the state population and representing Colorado's most populous region (Scott et al., 2020). These providers expanded their use of telemedicine after April 1, 2020, following an executive order that suspended state statues limiting the use of telemedicine due to the presence of COVID-19 in Colorado.

We included outpatient encounters with ≥1 AGE diagnosis using established International Classification of Diseases (ICD) diagnosis codes: ICD-10 codes A00–A08 (infectious gastroenteritis of known cause), A09 (diarrhea and gastroenteritis of presumed infectious origin), or K52.9 (noninfectious gastroenteritis and colitis, unspecified), excluding codes A04.7 (enterocolitis caused by C. difficile) and A05.1 (botulism) (Scallan et al., 2011). CHORDS provided counts of AGE encounters by age group (0–17, 18–39, 40–64, and 65+ years) and encounter type (in-person and telemedicine) aggregated by year and quarter (January–March, April–June, July–September, and October–December).

We calculated encounter rates by dividing the number of AGE encounters by the total number of outpatient encounters. AGE encounters in 2020 were compared with the 2017–2019 average using one-sample t-tests. Statistical analyses were performed using SAS 9.4 (SAS Institute, Inc., Cary, NC). This analysis did not meet the definition of human subjects research (as defined in the U.S. Code of Federal Regulations, Title 45 Part 46) and was not subject to review by an institutional review board.

Results

From 2017 to 2019, the average number of AGE outpatient encounters was 18,784, with an average of 325 AGE encounters per 100,000 total encounters (Fig. 1). AGE encounters demonstrated a seasonal pattern with most occurring in the first and fourth quarters of the year and a nadir in the third quarter. Children 0–17 years of age accounted for most AGE encounters (58% in 2017, 53% in 2018, 50% in 2019). Pediatric encounters were consistently higher than other age groups for all quarters, with most pediatric encounters occurring in the first and fourth quarters (Fig. 1).

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FIG. 1.

Frequency of outpatient encounters for acute gastrointestinal illness by year, quarter, and age group, the CHORDS, 2017–2020. CHORDS, Colorado Health Observation Regional Data Service.

In 2020, there were 9064 AGE encounters (168 per 100,000 total encounters), a 52% decrease from 2017 to 2019 (Fig. 1). Previously observed seasonal and age trend patterns were no longer evident. The rate of AGE encounters decreased after the first quarter of 2020 and remained significantly lower in the second (143 per 100,000 total encounters in 2020 vs. 314 in 2017–2019, p < 0.01), third (137 vs. 251, p < 0.01), and fourth quarters (95 vs. 335, p = 0.01). Statistically significant decreases were observed for those <65 years in the second quarter and for all age groups in the third and fourth quarters. Telemedicine was the visit modality for 23% of AGE encounters in 2020.

Discussion

AGE outpatient encounters in Colorado decreased significantly during 2020. These declines may represent an actual decrease in illness attributable to decreased exposure and transmission risk due to COVID-19 public health interventions, or a reluctance of people with AGE to seek medical care because of concerns about COVID-19 exposure during a health care visit, or a combination of the two.

Overall, AGE outpatient encounters decreased 52% in 2020 compared with those in the previous 3 years. This was particularly pronounced for children <18 years of age who accounted for most AGE encounters in previous years. Similar decreases in medical care seeking have been reported for other health conditions and in other health care settings (Hartnett et al., 2020; Wong et al., 2020). Harnett et al. (2020) reported a 42% decrease in emergency department visits during a 4-week period early in the COVID-19 pandemic when compared with the same 4-week period in 2019, also noting the largest decreases among children.

Seasonal increases in the number of AGE encounters typically observed during the fourth and first quarters of the year (October to March) were not evident during 2020. These seasonal trends were likely driven by norovirus, which causes a substantial burden of enteric illness in the United States with most cases occurring in the winter months (Hall et al., 2014). This lack of a seasonal peak in 2020 correlates with a decrease in reported norovirus outbreaks nationally and in Colorado (J Queen, Personal Communication; CDC, 2020).

The use of telemedicine increased dramatically during the pandemic. Regulatory changes expanded public and private insurer reimbursement, allowing providers to offer a wider range of telemedicine services to patients while minimizing the transmission risk of COVID-19 (Demeke et al., 2021). In our study, almost one-quarter of AGE encounters in 2020 were telemedicine visits. A previous analysis by the CHORDS network indicated that children <18 years of age were the highest adaptors of telemedicine (Colorado Health Institute, 2020). It is notable that the number of AGE visits declined and remained low despite the increased availability and use of telemedicine, especially among the <18-year-old population.

The increased use of telemedicine may also have impacted the frequency of stool specimen submission for enteric pathogen testing; however, data were not available to test this hypothesis. Stool sample submission and testing is essential for the diagnosis and reporting of bacterial enteric pathogens.

These findings are subject to several limitations. First, this analysis was restricted to counties and providers participating in the CHORDS network in Colorado. Second, our definition of AGE is not very specific and may include noninfectious causes of diarrhea. Third, we did not have access to laboratory testing data or data on the number of visits that resulted in the submission of a stool sample. Fourth, the time variable was aggregated by quarter to obtain encounter counts while observing data masking policies.

AGE outpatient encounters in Colorado in 2020 were substantially lower than during the previous 3 years. These decreases were especially pronounced for children <18 years of age. These results can be used when interpreting surveillance and outbreak trends during 2020.