Unveiling the Impact of Anemia of Chronic Disease: A Comprehensive Analysis of Mortality, Length of Stay, and Hospitalization Costs Using the NIS 2021 Database
Authors: Babu Kalaivani , Rajarajan Srinishant , Roy Arya Mariam , Correa Amit , Ramesh Nithya , Ramanan Sruthi P , Chattaraj Asmi , Dhamija Kriti , Khan Eiraj , Ayanambakkam Attanathi Adanma Anji 
Published: December 2024

Background: Anemia of chronic disease (AOCD) is a prevalent condition associated with conditions such as chronic infections, inflammatory diseases, autoimmune conditions, and malignancies. Recurring admissions for AOCD can impact the quality of life of patients and increase health care cost. This study evaluates the outcomes of patients with AOCD , focusing on mortality, hospital length of stay (LOS), and hospitalization charges using the National Inpatient Sample (NIS) 2021 data.

Methods: A retrospective analysis of the 2021 NIS database identified patients with AOCD using the appropriate ICD-10 codes. Adjusted regression analyses were performed to assess predictors for mortality of patients admitted with AOCD. The analysis was adjusted for covariates including age, sex, race, median household income by ZIP Code (Q1 denoting high income and Q4 denoting low income), Charlson Comorbidity Index, hospital region, teaching status, and hospital bed size.

Results: Among the 2,007,019 hospitalisations, 51.95% were male. The racial composition was predominantly White (54.01%), followed by Black (25.26%), Hispanic (13.68%), Asian/Pacific Islander (3.55%), Native American (0.86%), and Other (2.64%). The majority of patients had public insurance (69.14%), with the remainder having private insurance (13.62%), self-pay (14.99%), or other forms (2.25%). Hospital characteristics revealed that 52.18% of patients were treated in large hospitals, and 77.51% in teaching hospitals.

The overall mortality rate for AOCD patients was 5.11%. Mortality was significantly associated with age (OR=1.02, 95% CI [1.02, 1.02], p&lt;0.001), female sex (OR=0.89, 95% CI [0.86, 0.91], p&lt;0.001), and Black race compared to White race (OR=0.88, 95% CI [0.84, 0.92], p&lt;0.001). Other significant factors included median household income (2nd Quartile (Q) OR=0.94, 95% CI [0.90, 0.98], p=0.003; 3rd Q OR=0.90, 95% CI [0.86, 0.94], p&lt;0.001; 4th Q OR=0.85, 95% CI [0.80, 0.90], p&lt;0.001), and the Charlson Comorbidity Index (OR=1.09, 95% CI [1.08, 1.10], p&lt;0.001). Hospital region (West: OR=1.17, 95% CI [1.07, 1.27], p&lt;0.001), teaching status (OR=0.99, 95% CI [0.94, 1.04], p=0.67), and bed size (Medium: OR=1.08, 95% CI [1.00, 1.14], p=0.045; Large: OR=1.10, 95% CI [1.03, 1.17], p=0.002) were also relevant.

The mean hospital length of stay (LOS) was 7.68 days. Adjusted regression analysis indicated significant factors for LOS included age (β=-0.018, p&lt;0.001), female sex (β=-0.197, p&lt;0.001), and hospital characteristics. Specific racial influences on LOS included Asian/Pacific Islander (β=-0.205, p=0.022). Additional significant factors were hospital region (Midwest: β=-0.666, p&lt;0.001; South: β=-0.305, p=0.019; West: β=-0.771, p&lt;0.001), teaching status (β=1.018, p&lt;0.001), and bed size (Medium: β=0.478, p&lt;0.001; Large: β=1.206, p&lt;0.001).

The mean total hospitalization charges were $98,587.83. Significant factors influencing hospitalization charges included age (β=-545.979, p&lt;0.001), female sex (β=-6142.695, p&lt;0.001), and race. Notably, hospitalization charges were significantly higher for Asian/Pacific Islander (β=17063.95, p&lt;0.001). Additional influential factors included median household income (2nd Q: β=2719.852, p=0.041; 3rd Q: β=2879.346, p=0.056; 4th Q: β=8866.003, p=0.001), hospital region (Midwest: β=-26617.76, p&lt;0.001; South: β=-8987.225, p=0.033; West: β=15763.55, p=0.008), teaching status (β=19681.91, p&lt;0.001), and bed size (Medium: β=12617.57, p&lt;0.001; Large: β=23313.31, p&lt;0.001).

Conclusion: Patients with AOCD experience significant mortality, with outcomes influenced by demographic, socioeconomic, and hospital-related factors. Elderly patients and those with increased comorbidities had with higher mortality and female sex and Black race were associated with decreased mortality on admissions with AOCD. Our study underscores the need for targeted interventions for specific patient groups to improve outcomes in AOCD.