Adaptive Strategies for Outpatient Colonoscopies in Response to COVID-19.

INTRODUCTION

The COVID-19 pandemic caused a decline in outpatient colonoscopies that continues at varying levels.1 To prevent delay in colorectal cancer (CRC) diagnoses, centers strategized to expand fecal immunochemical tests (FIT) and triage symptomatic and FIT positive colonoscopies.2,3 While much has been written about missed CRC diagnoses,4 few studies have examined the impact of adaptive strategies on CRC and advanced polyp (AP) detection rates.5 It was hypothesized that these strategies would increase detection rates compared to pre-pandemic levels due to targeting of high-risk patients.

METHODS

After ethics board approval, CRC and AP diagnoses were identified in outpatient colonoscopy records of Boston Medical Center (BMC), a tertiary-care, safety-net hospital, between January 1, 2017, and June 30, 2021. BMC performs 7,429 ± 215 outpatient colonoscopies per year (2017‒2019). Adaptive strategies in response to COVID-19 were implemented to (1) strictly use FIT for average-risk CRC screening by educating primary care and GI providers (2) link FIT positive patients to colonoscopy and (3) prioritize symptomatic patients. Endoscopy capacity was drastically reduced during the first (March 16‒August 3, 2020) and second (December 14, 2020 to March 1, 2021) pandemic surges and affected by poor show rates.

Colonoscopies performed for screening for CRC, polyp surveillance, positive FIT, symptoms other than diarrhea, follow-up of abnormal imaging or conditions like diverticulitis were included and those for inflammatory bowel disease, diarrhea, history of CRC, and therapeutic indications were excluded (11% of cases). APs were defined as adenomas ≥10 mm or with tubulovillous/villous histology or high-grade dysplasia,6 or sessile serrated lesions ≥10 mm or with dysplasia, or traditional serrated adenomas.7 The primary outcome was the frequency of CRC and APs detected per month. Poisson regression modeling, fit with calendar month (due to seasonality), age, race, sex, and indication, was used to estimate frequencies of CRCs and APs per month with 95% CIs using data from 2017‒2019 and assuming similar outpatient volume and patient characteristics as 2019 in 2020‒2021. Observed and expected frequencies under a Poisson distribution were compared using chi-square tests after the first surge when adaptive strategies were fully implemented.

RESULTS

After the first and second COVID-19 surges there were 27% (434 vs 592) and 15% (493 vs 577) fewer colonoscopies per month, respectively, as compared to 2019. The actual and predicted number of CRC and APs detected by outpatient colonoscopies per month are presented in Figure 1 .

Figure 1

(A) Expected versus observed number of colorectal cancers detected per month (with 95% CI) from January 2017 to June 2021; (B) Expected versus observed number of advanced polyps detected per month (with 95% CI) from January 2017 to June 2021.

Between August 2020 and February 2021, an average of 2.3 ± 1.4 CRCs were detected per month (0.63 per 100 colonoscopies), which was comparable (χ2 =6.12 df=5 p=0.2872) to the expected frequency of 2.5 ± 1.3 per month (0.45 per 100 colonoscopies). However, between March and June 2021, the observed frequency of 4.3 ± 2.1 CRCs detected per month (1.25 per 100 colonoscopies) was significantly higher (χ2 =11.38 df=2 p=0.0034) than the expected frequency of 2.8 ± 0.6 per month (0.48 per 100 colonoscopies).

Between August 2020 and February 2021, the observed frequency of APs detected per month was significantly lower than the expected frequency (χ2 =36.9 df=5 p<0.00001), though AP detection rate was similar (7.3 vs 8.0 per 100 colonoscopies). Between March and June 2021, the observed frequency of APs detected per month was higher at 40.0 ± 10.7 (11.75 APs per 100 colonoscopies) as compared to an expected frequency of 36.2 ± 10.7 (6.3 APs per 100 colonoscopies) (χ2 =10.8 df=2 p=0.0045).

DISCUSSION

Adaptive strategies for outpatient colonoscopies in response to COVID-19 led to higher CRC and AP diagnoses per month compared to predicted values by June 2021 as colonoscopies were performed on patients with higher risk of CRCs or APs. FIT-positive and symptomatic patients were both prioritized, as they had similar rates of CRC detection (1.7 per 100 colonoscopies). CRC and AP detection per month were higher in the second post-surge period potentially due to better show rate and streamlining of strategies.

Adaptive strategies were less effective for APs, as the sensitivity of FIT for advanced adenomas is low.8 The first post surge period also had more symptomatic patients who had lower AP detection rate compared to FIT-positive (5.5 versus 19.6 per 100 colonoscopies). Further studies are needed to understand the long-term impact of these strategies on AP detection, CRC prevention and stage of CRC diagnosis.

This study shows that adaptive outpatient strategies to the COVID-19 pandemic can potentially mitigate the previously predicted increase in CRC incidence and mortality. Here, key outcomes were evaluated using robust prediction models in a real-world scenario where experimental approaches were impractical. The results are potentially generalizable, as the study population is diverse, and centers nationwide have faced similar disruptions.

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CRediT authorship contribution statement

Heidi S. Ahmed: Conceptualization, Data curation, Investigation, Writing – original draft. James J. Connolly: Data curation, Investigation, Writing – review & editing. Enoch C. Chung: Data curation. Howard J. Cabral: Formal analysis, Writing – review & editing. Paul C. Schroy III: Writing – review & editing. Arpan Mohanty: Conceptualization, Project administration, Supervision, Methodology, Visualization, Formal analysis, Software, Investigation, Writing – review & editing.