Validation of Ultrasonographic Criteria for Diagnosing Сlostridioides difficile Colitis in COVID-19 and Non-COVID-19 Patients With Antibiotic-Associated Diarrhea

Objective : To assess the validity of developed ultrasonographic criteria for diagnosing Clostridioides (formerly Clostridium ) difficile ( C difficile ) colitis in COVID-19 and non-COVID-19 patients. Materials and methods : We examined 253 patients (85 men and 168 women) aged 18-100 years with antibiotic-associated diarrhea (AAD). The diagnosis of C difficile colitis was verified in 86 of 136 COVID-19 patients and in 75 of 117 non-COVID-19 patients. We used the developed ultrasonographic criteria for diagnosing C difficile colitis in the patients with AAD. Internal validation of cut-off values of colon wall thickness was performed by means of a bootstrap method using the main group according to the Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis guidelines and the Prediction Model Risk of Bias Assessment Tool algorithm. Results : The internal validation revealed that the determined cutoff values of colon wall thickness were resistant to data variation in the target population, confirming great generalizability of the proposed cutoff values. Conclusions : The established ultrasonographic criteria for diagnosing C difficile colitis (colon wall thickness greater than 4.0 mm in COVID-19 patients with AAD and greater than 3.2 mm in non-COVID-19 patients with AAD) are valid and can be effectively used in clinical practice.