Relationship between Natural Killer Lymphocytes and Length of Stay in Patients with Depression admitted with Corona Virus-19

Introduction: The recent unexpected COVID-19 pandemic had a serious and sudden impact on the world population physically and mentally. In the current study, we collected data prospectively on COVID-19 infected patients with depression/anxiety admitted to the hospital to evaluate the effect of these illnesses on patient length of stay and the level of Natural Killer Lymphocytes.

Methods: This project was a prospective study of patients admitted between July 2021 - July 2022 with COVID-19 to our community hospital. Patients completed the PHQ-9 and GAD-7 questionnaires to assess levels of depression and anxiety. A blood draw was done to check levels of natural killer lymphocyte cells (NKL). Data collected included age, sex, race, history of diabetes, hypertension, chronic obstructive pulmonary disease, hyperlipidemia, chronic kidney disease, obesity, length of stay, and mortality. Student’s t-Test, Chi-square, and Pearson’s correlation were used to identify the relationship of these patients to their NKL response and length of stay.

Results: There were a total of 67 patients enrolled. Of those 67 patients, 49 (73.1%) had labs drawn to measure NKL levels and were included in the analysis. Mean age was 61.8 (SD: 11.4). Over half of the participants were female (n=26, 53.1%). There were 30 (61.2%) patients with depression and 22 (44.9%) with anxiety. There were 26 (53.1%) patients with hypertension, 16 (32.7%) with diabetes, and 14 (28.6%) patients with chronic obstructive pulmonary disease. The mean Natural Killer lymphocyte was 82.3% (SD ±12.1) (which includes (CD3-CD16+CD56 dim and CD3-CD16+CD56 bright). The overall relationship between length of stay and combined NKL demonstrated a nonsignificant weak negative correlation (n=45, r= -0.07, p=.65). Patients with pre-existing chronic kidney disease had the highest NKL cell level (88.2) and the lowest LOS (5.4 days), and patients with Hypertension and hyperlipidemia had the lowest natural killer lymphocyte cell level (80.2 and 80.1 respectively) had the highest length of stay (8.6 and 10.1 days respectively).

Conclusion: Depression and anxiety did not influence length of stay of COVID-19 patients. NKL response and its relation to length of stay largely dependent on the associated comorbid conditions. Diabetes mellitus in patients with COVID-19 is a significant predictor of length of stay.