Risk factors of long COVID among discharged patients with omicron infection in Changzhi, China: a retrospective cohort study.

BACKGROUND: Relatively little is known about long COVID (LC) in China, particularly regarding the effects of recent Omicron sub-lineages. Therefore, we systematically assessed the prevalence and risk factors for developing LC. METHODS: This retrospective cohort study included COVID-19 patients who had been hospitalized at two hospitals in Changzhi, China, between December 15, 2022 and April 30, 2024. All patients were interviewed via telephone ≥ 3 months after discharge. The follow-up study was conducted between July 18 and August 20, 2024. Logistic regression models were used to analyze risk factors for developing long COVID. RESULTS: A total of 2,765 patients (1,407 male [50.9%]; median [IQR] age 70.0 [59.0-78.0] years) were successfully evaluated by telephone; 458 (16.6%) self-reported long COVID symptoms. The most common symptom was fatigue (4.9%), followed by muscle weakness (3.9%), sleep difficulties (3.0%), brain fog (2.8%) and cough (2.5%). Severe COVID-19 patients had a higher risk of LC than non-severe patients (OR = 1.275, 95% CI: 1.036-1.570). In subgroup analyses stratified by follow-up time, overweight patients (OR = 1.564; 95% CI: 1.052-2.326), patients with ≥ 7 acute-phase symptoms (OR = 1.275; 95% CI: 1.064-1.528), and farmer (OR = 1.439, 95% CI: 1.047, 1.976) had a higher risk of LC, whereas individuals who received immunosuppressant therapy had a lower risk (OR = 0.691, 95% CI: 0.504, 0.948). In addition, aged ≥ 50 years (OR = 2.441, 95% CI: 1.175-5.072) and underweight status (OR = 2.183; 95% CI: 1.115-4.273) were associated with a higher risk of muscle weakness. CONCLUSION: This study provides valuable insights into LC after discharge, with 16.6% of discharged patients reporting symptoms. It is essential to monitor at-risk individuals according to identified risk factors for public health efforts.