Missed visits have been estimated to cost the U.S. healthcare system $50 billion annually and have been linked to healthcare inefficiency, higher rates of emergency department visits, and worse outcomes. COVID-19 disrupted existing outpatient healthcare utilization patterns. In our study, we sought to examine the frequency of missed outpatient visits over the course of the COVID-19 pandemic and to examine patient-level characteristics associated with non-attendance. This study utilized data from a longitudinal cohort study (the Chicago COVID-19 Comorbidities (C3) study). C3 participants were enrollees in 1 of 4 active, "parent" studies; they were rapidly enrolled in C3 at the onset of the pandemic. Multiple waves of telephone-based interviews were conducted to collect experiences with the pandemic, as well as socio-demographic and health characteristics, health literacy, patient activation, and depressive and anxiety symptoms. For the current analysis, data from waves 3 to 8 (05/01/20-05/19/22) were analyzed. Participants included 845 English or Spanish-speaking adults with 1 or more chronic conditions. The percentage of participants reporting missed visits due to COVID-19 across study waves ranged from 3.1 to 22.4%. Overall, there was a decline in missed visits over time. No participant sociodemographic or health characteristic was consistently associated with missed visits across the study waves. In bivariate and multivariate analysis, only patient-reported anxiety was significantly associated with missed visits across all study waves. Findings reveal that anxiety was consistently associated with missed visits during the COVID-19 pandemic, but not sociodemographic or health characteristics. Results can inform future public health initiatives to reduce absenteeism by considering patients' emotional state during times of uncertainty.