Highlight
– General Internal Medicine (GIM) admissions increased by 17% between 2015-2016 and 2021-2022 across 21 hospitals in Ontario.
– Patient complexity metrics such as age, comorbidity profiles, in-hospital mortality, and laboratory testing showed no consistent rise over the study period.
– Significant and consistent increases were observed in the utilization of advanced imaging, specifically CT and MRI scans.
– The COVID-19 pandemic was associated with transient increases in complexity indicators such as length of stay, mortality, and care costs.
Study Background
Understanding changes in inpatient complexity over time is critical for hospital resource planning and patient care optimization. General Internal Medicine manages a broad array of medical conditions often involving elderly patients with multiple comorbidities. While hospital admission rates and resource utilization evolve, it remains unclear whether complexity in GIM inpatients has increased, which could contribute to healthcare capacity strain. This study aimed to quantify trends in patient complexity and associated care demands over a seven-year period spanning pre-pandemic and pandemic intervals.
Study Design
This retrospective cohort analysis leveraged individual-level clinical and administrative hospitalization data for GIM inpatients admitted to 21 hospitals in Ontario between April 2015 and June 2022. The cohort comprised 687,512 hospitalizations with a median patient age of 73 years and equal sex distribution. Complexity was assessed through multiple parameters, including demographic features (e.g., advanced age), clinical outcomes (e.g., in-hospital mortality), processes of care such as laboratory utilization and imaging, and resource consumption metrics like hospital length of stay and cost. Admissions were classified dichotomously into complex and non-complex categories. Generalized linear mixed-effects models estimated adjusted rate ratios representing relative monthly admission changes per year compared to baseline 2015-2016 values.
Key Findings
The volume of GIM hospitalizations increased by 17%, rising from 103,851 admissions in 2015-2016 to 121,103 in 2021-2022. Analysis of patient characteristics revealed no substantial or consistent shifts in age distribution or other demographic complexity indicators over time. Similarly, clinical outcomes such as in-hospital mortality and common laboratory test frequencies remained stable across the study decades.
In contrast, diagnostic imaging utilization exhibited marked growth. The proportion of hospitalizations involving CT scans increased from 49% in 2015-2016 to 61% in 2021-2022, with an adjusted rate ratio of 1.45 (95% CI 1.40-1.50). MRI scan usage rose from 11% to 14%, adjusted rate ratio 1.46 (95% CI 1.39-1.54). This rise in imaging intensity occurred despite stable patient complexity, suggesting changes in clinical practice or investigation thresholds rather than patient-driven complexity escalation.
The COVID-19 pandemic period (April 2020-June 2022) correlated with increases in hospital length of stay, in-hospital mortality, laboratory testing utilization, and care costs, signaling pandemic-driven healthcare delivery challenges and shifts in patient acuity.
Expert Commentary
The findings challenge a common perception that inpatient populations are necessarily becoming more medically complex over time. Instead, the data suggest increasing hospital burden arises partly from higher admission volumes and intensified use of specific diagnostic tests like advanced imaging modalities. The rapid growth in CT and MRI utilization, without corresponding increases in measured clinical complexity or mortality, raises crucial questions about appropriateness and cost-effectiveness. It may reflect evolving diagnostic strategies, defensive medicine, or availability of technology rather than patient need.
These trends underscore the need for nuanced evaluation of resource allocation and utilization patterns in hospital medicine. Further research should explore drivers contributing to increased imaging, potential impacts on clinical outcomes, and whether there are opportunities for optimizing care delivery to balance diagnostic benefits with resource stewardship.
Limitations include reliance on administrative data which may omit subtler aspects of clinical complexity, and the inability to fully capture outpatient or community disease burden influences. The pandemic-related changes also confound temporal trends somewhat but are important contextual factors.
Conclusion
Between 2017 and 2022, General Internal Medicine hospitalizations increased substantially in Ontario. However, patient complexity as measured by demographics, clinical outcomes, and laboratory utilization did not similarly increase. Instead, the notable rise in imaging—particularly CT and MRI—highlighted evolving care intensity. The data prompt careful scrutiny of imaging indications and resource use, especially in the context of stable patient complexity. Understanding these dynamics is essential for designing effective hospital resource strategies and ensuring high-value care delivery.
Future studies should incorporate detailed clinical parameters and evaluate long-term outcomes to refine insight into inpatient complexity and resource utilization trends beyond administrative coding metrics.