**Background:** COVID-19, caused by SARS-CoV-2, has been associated with high hospitalization rates and mortality, particularly in patients with comorbidities such as hypertension, diabetes, cardiovascular disease, and obesity. Malnutrition and muscle loss are common in hospitalized COVID-19 patients and may worsen outcomes. Phase angle (PhA), a bioelectrical impedance analysis (BIA)-derived parameter reflecting cellular health and membrane integrity, and handgrip strength (HGS), a measure of muscle strength, have been proposed as prognostic markers in various diseases. Previous studies suggested that low PhA is associated with increased mortality, prolonged ICU stay, and mechanical ventilation in COVID-19 patients, while low HGS may predict severe disease and adverse clinical events. This study aimed to investigate the relationship between PhA, HGS, anthropometric and biochemical parameters, and clinical outcomes in hospitalized COVID-19 patients.
**Methods:** This observational study was conducted at AHEPA General Hospital of Thessaloniki, Greece, from November 2021 to March 2022. Eligible patients were adults aged 18–75 years with PCR-confirmed SARS-CoV-2 infection. Exclusion criteria included age <18 or >75 years, pregnancy, liver cirrhosis, dialysis, end-stage cancer, severe physical disability, suitability for outpatient treatment, or direct ICU admission. Demographic data, comorbidities, vaccination status, and laboratory values (albumin, CRP, IL-6, neutrophil-to-lymphocyte ratio, ferritin, uric acid, phosphorus, D-dimers) were collected. BIA was performed using a Bodystat Quadscan 4000 device to measure PhA, and HGS was measured with a calibrated Jamar hand dynamometer (three attempts, largest value recorded). Measurements were taken on day 1 (admission) and day 7 of hospitalization. The primary outcome was 28-day clinical status (discharge, hospitalization, or death). Secondary outcomes included length of stay (LOS), BMI, CRP, ferritin, albumin, oxygen requirements, and pneumonia stage (classified by CT from stage 1–5). Statistical analysis used Wilcoxon signed-rank, Kruskal-Wallis, ANOVA with Bonferroni correction, and Spearman correlation, with significance set at p < 0.05.
**Key Results:** A total of 102 patients were enrolled (median age 59 years, IQR 47.5–67; median BMI 29 kg/m², IQR 25–32.5; 59.8% male; 83.3% non-smokers). Common comorbidities included hypertension (30.4%), dyslipidemia (25.5%), diabetes (15.7%), and obesity (15.7%). On day 1, median PhA was 6.1° (IQR 5.2–8.3) and mean HGS was 34.1 kg (SD 14.1); on day 7, median PhA was 5.95° (IQR 4.8–9.8) and mean HGS was 34.9 kg (SD 14.5). Mean CRP decreased from 7.6 mg/dL (SD 5.6) on day 1 to 1.3 mg/dL (SD 1.6) on day 7. Mean albumin on day 1 was 3.6 g/dL (SD 0.4), and median ferritin was 577 ng/mL (IQR 246–986). By day 28, 84 patients were discharged, 4 remained hospitalized, and 12 had died. For the primary outcome, no significant difference was found between PhA on day 1 (p = 0.769) or day 7 (p = 0.807) and 28-day clinical status. Similarly, HGS on day 7 showed no association (p = 0.476). However, HGS on day 1 was significantly associated with 28-day clinical status (p = 0.008). Post-hoc analysis revealed that discharged patients had significantly higher mean HGS on day 1 (40.1 kg) compared to those who died (30.9 kg, p = 0.04). HGS in patients still hospitalized at day 28 did not differ from either group (p = 0.972). For secondary outcomes, LOS was not correlated with PhA day 1 (r_s = −0.081, p = 0.422) or HGS day 1 (r_s = 0.137, p = 0.177). PhA day 1 did not correlate with ferritin (r_s = 0.092, p = 0.370) or CRP (r_s = −0.043, p = 0.680), but showed a significant positive correlation with albumin (r_s = 0.286, p = 0.006). PhA day 1 did not differ across oxygen requirement categories (day 1, p = 0.733; day 7, p = 0.603) or pneumonia stages (p = 0.371). On day 7, a significant difference was found between oxygen requirements and BMI (p = 0.005), with patients requiring no oxygen support having lower median BMI than those needing ≤4 L O₂/day (p = 0.002).
**Clinical Implications:** This study suggests that handgrip strength measured at hospital admission may serve as a simple, inexpensive prognostic tool for identifying COVID-19 patients at higher risk of mortality. Patients with lower HGS on admission (mean 30.9 kg in non-survivors vs. 40.1 kg in survivors) warrant closer monitoring and potentially earlier intervention. The lack of association between PhA and clinical outcomes contrasts with several previous studies, possibly because most patients in this cohort had near-normal PhA values at admission (median 6.1°). The positive correlation between PhA and albumin supports the role of both as nutritional status indicators, though inflammation may confound this relationship. The finding that higher BMI was associated with greater oxygen requirements on day 7 reinforces the known link between obesity and COVID-19 severity. Limitations include the small sample size (n = 102), single-center design, and inability to assess nutritional status with validated screening tools. Larger multicenter studies are needed to confirm HGS as a prognostic marker and to clarify the role of PhA in COVID-19 outcomes.