Postacute Sequelae Following Omicron COVID-19 in Patients With Cancer.

Importance: Information on the burden of postacute sequelae of SARS-CoV-2 infection (or long COVID) in patients with cancer during endemicity is limited. Objective: To evaluate the risk of postacute diagnoses and/or symptoms compatible with long COVID in a population-based cohort of patients with cancer and high rates of vaccination and/or boosting who were infected during Omicron predominance compared with those with negative test results (hereinafter, noninfected patients). Results were additionally stratified by COVID-19 severity and receipt of therapeutics. Design, Setting, and Participants: This retrospective, population-based cohort study used health care claims databases to construct cohorts of adult patients with cancer in Singapore who were infected with SARS-CoV-2 during Omicron predominance (January 1 through December 31, 2022), and contemporaneous noninfected patients. Patients were followed up to 300 days from the index date and data were analyzed from February 1, 2022, through October 27, 2023. Exposure: SARS-CoV-2 infection. Main Outcomes and Measures: Competing risks regression (death as a competing risk), with overlap weights applied, was used to estimate risks of new-incident diagnoses and/or symptoms compatible with long COVID following SARS-CoV-2 infection in patients with cancer compared with noninfected patients. Risks of postacute sequelae following COVID-19 hospitalization in patients with cancer were further contrasted against influenza hospitalizations (January 1, 2017, to December 31, 2022). Results: A total of 76 807 patients with cancer were included in the analysis (48 279 [62.9%] female); 39 256 had SARS-CoV-2 infection and 37 551 were noninfected patients. The mean (SD) age was 63.9 (13.7) years. The mean (SD) follow-up time was 263.1 (36.2) days for patients infected with SARS-CoV-2 and 264.8 (32.5) days for noninfected patients. Most patients had solid-organ cancer (72 497 of 76 807 [94.4%]) and were boosted (71 550 of 76 807 [93.2%]); only a minority with SARS-CoV-2 infection (3571 of 39 256 [9.1%]) required acute hospitalization. No significant difference in risk of postacute diagnoses compatible with long COVID was observed in patients with SARS-CoV-2 infection (hazard ratio [HR], 0.98; 95% CI, 0.92-1.04) compared with noninfected patients. While risk of postacute symptoms following COVID-19 was modestly increased (HR, 1.09; 95% CI, 1.01-1.19; P = .048), statistical significance was not attained after adjustment for multiple comparisons. However, significantly increased risk of postacute sequelae was observed among patients hospitalized for COVID-19 compared with noninfected patients (HR for any diagnosis, 1.36 [95% CI, 1.18-1.56]; HR for any symptom, 1.48 [95% CI, 1.22-1.76]; P < .001 for both); risks remained elevated even among hospitalized cases receiving COVID-19 therapeutics. Risks of postacute sequelae following COVID-19 hospitalization in patients with cancer did not significantly differ from those associated with seasonal influenza hospitalizations. Conclusions and Relevance: The findings of this cohort study suggest that among highly boosted patients with cancer, the overall risk of postacute sequelae following Omicron SARS-CoV-2 infection was not significantly elevated compared with noninfected patients; however, patients who were hospitalized for COVID-19 remained at increased risk of postacute sequelae despite administration of COVID-19 therapeutics. These findings further suggest that COVID-19 vaccination and boosting remain important in mitigating the risk of long COVID among immunocompromised patients during endemicity.