**Background:** Patients with end-stage renal disease on dialysis or with kidney transplants are at high risk for severe COVID-19 and its long-term sequelae. Gastrointestinal (GI) involvement in Long-COVID is poorly characterized in these immunosuppressed populations. This study aimed to determine the prevalence and characteristics of GI manifestations of Long-COVID in dialysis-dependent patients and kidney transplant (KT) recipients.
**Methods:** This prospective, observational cohort study enrolled 645 eligible participants (588 hemodialysis [HD], 38 peritoneal dialysis [PD], 19 KT recipients) with RT-PCR-confirmed COVID-19 infection from January 1 to July 31, 2022, across three renal referral tertiary care centers in Thailand. Of these, 577 (89.5%) agreed to interviews at 3 months post-onset. Exclusion criteria included death before follow-up, inability to contact, or lack of consent. Trained research nurses conducted structured interviews (in-person or by telephone) to assess persistent or emerging GI symptoms including loss of appetite, nausea, weight loss, abdominal pain, heartburn, dysphagia, diarrhea, constipation, altered bowel motility, and irritable bowel syndrome. Clinical data were extracted from electronic medical records. Statistical analyses used chi-square tests, Tukey-Kramer multiple comparisons, and backward stepwise binary regression.
**Key Results:** The mean age was 52 ± 11 years, 52% were women. Median dialysis vintage was 7 ± 3 years (HD) and 5 ± 1 years (PD); median post-transplantation time was 6 ± 2 years. Hypertension (92%) and type 2 diabetes (77%) were the most common comorbidities. All participants were hospitalized per Thai national guidelines. Long-COVID was identified in 293/524 (56%) of HD, 21/34 (62%) of PD, and 7/19 (37%) of KT patients. Fatigue was the most prevalent non-GI symptom (96%). Among GI manifestations, anorexia was most common (525 cases, 90.9% across all groups), followed by loss of taste (372 cases, 64.4%), and abdominal pain (367 cases, 62.5%). Anorexia and loss of taste improved by 2 months in most cases, while abdominal pain and diarrhea persisted beyond 3 months. Notably, 6 of 19 KT recipients with GI symptoms were diagnosed with mesenteric panniculitis, all of whom had complete resolution after 8 weeks of oral prednisolone (20 mg, tapered). Risk factors for GI Long-COVID included age >65 years (OR 2.00, 95% CI 1.2–2.8), chronic lung disease (OR 2.10, 95% CI 1.1–4.2), PD modality (OR 1.80, 95% CI 1.4–2.5), and elevated C-reactive protein (>5 mg/L) plus D-dimer (>500 ng/mL) at onset (OR 4.40, 95% CI 1.4–8.8).
**Clinical Implications:** GI manifestations of Long-COVID are highly prevalent in dialysis and KT populations, with a different symptom profile (predominantly anorexia and abdominal pain) compared to the general population (where diarrhea is most common). The finding of mesenteric panniculitis in KT recipients—a rare but treatable condition—underscores the need for diagnostic vigilance. The authors propose a revised nomenclature distinguishing post-acute COVID-19 syndrome (<3 months), chronic COVID-19 syndrome (3–6 months), and Long-COVID syndrome (>6 months). Limitations include the single-country design, small KT sample size, lack of non-COVID controls, and absence of data on SARS-CoV-2 variants and vaccination status. Larger multinational studies are needed to confirm these findings and explore underlying mechanisms such as gut dysbiosis and immune dysregulation.