Impact of COVID-19 Vaccination on Outcomes in Geriatric Hip Fracture Patients

Geriatric patients with hip fractures face high morbidity, mortality, and healthcare costs. During the COVID-19 pandemic, older and immunocompromised individuals have been at highest risk for severe infection, ICU admission, and death, with over 81% of COVID-19 deaths occurring in those older than 65 years. Early pandemic data indicated COVID-19 positivity independently increased inpatient mortality among geriatric hip fracture patients. Since late 2020, COVID-19 vaccines and, subsequently, boosters have been deployed and shown to reduce infection, hospitalization, and death. This study aimed to determine the impact of COVID-19 vaccination and booster status on outcomes among geriatric hip fracture patients, hypothesizing that vaccination (including booster dosing) improves outcomes.

Prior research demonstrates mRNA vaccines (Pfizer-BioNTech and Moderna) substantially reduce SARS-CoV-2 infection and severe outcomes, with evidence of waning immunity mitigated by booster doses. Observational data from multiple settings show vaccinated individuals are markedly less likely to be hospitalized or die from COVID-19. Early pandemic hip fracture studies in New York City showed higher inpatient mortality and major complications associated with COVID-19 positivity. Vaccination has been emphasized for older adults (≥65 years) due to higher risk, and boosters increase protection in the context of variants such as Delta and Omicron.

Design: Retrospective cohort study using an IRB-approved geriatric trauma database at a single academic medical center. Timeframe: December 2020 to January 2022. Population: Patients aged ≥55 years with low-energy hip fractures, including subtrochanteric, femoral neck, or intertrochanteric fractures (AO/OTA 31A, 31B, 32A–C). Exclusions: Age <55 years or high-energy mechanism. Exposure (vaccination status): Non-vaccinated (NV); partially vaccinated (PV: 1 dose Pfizer/Moderna); fully vaccinated (FV: 2 doses Pfizer/Moderna or 1 dose Janssen); boosted (BV: full vaccination plus booster). COVID-19 positivity defined by RT-PCR positivity on admission. Variables collected: Demographics (age, sex, BMI), comorbidity burden (Charlson Comorbidity Index, CCI), baseline ambulatory status; injury severity (GCS, AIS Head/Neck, AIS Chest); fracture classification; treatment modality (e.g., short/long IM nail, hemiarthroplasty, THA, CRPP, sliding hip screw, nonoperative); hospital quality measures (length of stay [LOS], ICU level care); complications during index hospitalization (minor: pneumonia, ARF/AKI, SSI, decubitus ulcer, UTI, anemia; major: sepsis/septic shock, DVT/PE, MI, stroke, acute respiratory failure, cardiac arrest); mortality (inpatient and 30-day); readmissions (30 and 90 days); discharge disposition. Analyses: Primary comparison of any vaccinated (PV+FV+BV combined) vs NV. Subgroup comparisons of PV, FV, and BV each vs NV. Descriptive statistics used for demographics; continuous variables compared via t-test or ANOVA; categorical via chi-square. Multivariable logistic regression assessed independent associations with need for ICU care and minor complications, including covariates from univariate analyses. Software: IBM SPSS v25. Alpha 0.05.

Cohort: 506 patients ≥55 years; NV 329 (65%), PV 14 (3%), FV 138 (27%), BV 25 (5%); mean age 80.03±10.85; 67% female; mean BMI 24.11±5.14; mean CCI 1.51±1.74. Baseline demographics, ambulatory status, and treatment modalities were similar between vaccinated and NV groups. COVID-19 positivity on admission: 28 (5.5%), all symptomatic; 20 (71%) NV and 8 (29%) vaccinated (0 PV, 7 FV, 1 BV). Outcomes (vaccinated vs NV):

• Minor complications: 26.55% vs 37.99%, p<0.01 (significantly lower with vaccination). Among COVID+ patients: 12.50% vs 60.00%, p=0.023. Among COVID− patients: 27.22% vs 36.57%, p=0.036.
• Major complications: 12.43% vs 13.68%, p=0.683 (no significant difference).
• ICU level care: 6.21% vs 14.89%, p<0.01 (significantly lower with vaccination). In COVID−: 5.92% vs 14.89%, p<0.01; in COVID+: 12.50% vs 15.00%, p=0.864.
• LOS: 5.58±4.77 vs 6.22±3.24 days, p=0.235 (ns). Among COVID+: 7.75±5.39 vs 12.70±10.53, p=0.221 (ns).
• Home discharge: 34.46% vs 30.70%, p=0.387 (ns).
• Readmission 30 days: 9.60% vs 5.17%, p=0.069 (ns overall); in COVID+: 25.00% vs 0%, p=0.037 (small numbers).
• Readmission 90 days: 14.69% vs 11.85%, p=0.432 (ns).
• Inpatient mortality: 1.13% vs 3.34%, p=0.133 (ns); 30-day mortality: 4.52% vs 6.69%, p=0.325 (ns). Mortality rates were numerically lower in vaccinated groups but not statistically significant. Subgroup (PV, FV, BV vs NV): Similar patterns observed: reduced minor complications and ICU need with vaccination; no significant differences in major complications, LOS, discharge disposition, or mortality. Multivariable logistic regression:
• Need for ICU level care: COVID-19 vaccination independently protective (OR 0.655, 95% CI 0.470–0.913, p=0.013). Age (OR 1.030, p=0.051) borderline; other covariates not significant.
• Minor complications: COVID-19 vaccination independently protective (OR 0.767, 95% CI 0.628–0.937, p<0.01); female gender protective (OR 0.629, p=0.028); increasing age (OR 1.040 per year, p<0.01) and higher CCI (OR 1.140 per point, p=0.019) increased risk.

Consistent with broader evidence that COVID-19 vaccination reduces disease severity, vaccinated geriatric hip fracture patients had significantly fewer minor inpatient complications and a markedly reduced need for ICU care compared with non-vaccinated patients. These effects were evident even among COVID-negative patients, suggesting system-level and clinical benefits such as improved resource availability and possibly more effective floor-based care and mobilization. Although mortality differences favored vaccinated patients, the study was underpowered to detect statistically significant differences in inpatient or 30-day mortality. The reduction in ICU utilization is clinically and operationally meaningful, particularly during pandemic surges when ICU capacity constraints can adversely affect care. Lower minor complication rates may reflect attenuation of COVID-related illness severity and downstream benefits such as earlier mobilization, reduced risk of hospital-acquired infections (e.g., HAP, UTI, pressure ulcers), and enhanced rehabilitation. Multivariable analyses confirm vaccination as an independent protective factor for both ICU need and minor complications, while older age and higher comorbidity burden predict higher minor complication risk and female sex is protective.

In a single-center cohort of geriatric hip fracture patients during the COVID-19 vaccine era, any COVID-19 vaccination status (including partial, full, or boosted) was associated with significantly reduced minor inpatient complications and decreased need for ICU-level care, with trends toward lower inpatient and 30-day mortality that did not reach statistical significance. These findings support vaccination as a key component of perioperative risk mitigation in this vulnerable population. Future research should include larger multicenter cohorts to better assess mortality effects, stratify by vaccine brand and timing, evaluate booster-specific impacts, and account for evolving SARS-CoV-2 variants.

Single health system experience may limit generalizability to other settings. Retrospective design introduces potential selection and information biases. The dynamic nature of the pandemic and variant evolution may affect applicability over time. Heterogeneity in vaccine brand and timing relative to admission, as well as small subgroup sizes (especially partially vaccinated and boosted), limit precision and power, particularly for mortality and readmission outcomes.