Ambulatory Care-Sensitive Hospitalizations Among Adults and Older Adults Analyzed by Diagnosis-Related Groups

Technical Summary: Ambulatory Care-Sensitive Hospitalizations Among Adults and Older Adults Analyzed by Diagnosis-Related Groups

Problem Statement
The study addresses the growing burden of hospitalizations for ambulatory care-sensitive conditions (ACSCs) within Brazil's Unified Health System (SUS). ACSCs are defined as hospital admissions that could potentially be prevented through timely and effective primary health care (PHC). With Brazil undergoing rapid demographic transition and population aging, the demand for health services is increasing, particularly for chronic non-communicable diseases (NCDs). Despite PHC serving as the preferred entry point and coordinator of care in Brazil, hospital admissions for conditions such as heart failure, hypertension, and cerebrovascular diseases remain high. These admissions indicate potential weaknesses in longitudinal follow-up, clinical management, and care coordination, leading to avoidable healthcare costs and resource strain. While ACSCs are recognized as indicators of PHC quality, there is a gap in understanding these hospitalizations specifically through the lens of the Diagnosis-Related Groups (DRG) system, which links clinical complexity to resource utilization and costs.

Methodology
This epidemiological study analyzed secondary data from 916,676 hospital admissions involving adults and older adults (aged 18 years and older) across all five regions of Brazil between 2018 and 2024. The analysis utilized the DRG system, which classifies patients based on clinical characteristics and resource requirements.

• Data Source: Anonymized data from the institutional DRG database of participating hospitals.
• Inclusion Criteria: Admissions classified within the DRG system with discharge dates between 2018 and 2024. Records with incomplete information were excluded.
• Variables Analyzed:
  • Sociodemographic: Age, sex, age group.
  • Clinical/Healthcare: DRG disease group, DRG classification (medical vs. surgical), length of hospital stay, number of procedures, number of secondary ICD-10 diagnoses, clinical severity, and hospital outcome (survival/death).
• Classification: Admissions were categorized according to the Brazilian List of Hospitalizations for ACSCs (Ministry of Health Ordinance No. 221/2008), grouping them into 19 diagnostic categories (e.g., anemia, angina, asthma, diabetes, hypertension, heart failure, bacterial pneumonia).
• Statistical Analysis: Performed using R software. Descriptive statistics were used to summarize distributions, with categorical variables presented as frequencies and continuous variables as means and standard deviations.
• Ethical Considerations: The study was approved by the Research Ethics Committee (CAAE: 09709118.0.0000.5149) with a waiver of informed consent due to the retrospective nature of the data collection from medical records.

Key Results

• Leading Causes of Admission: Noncommunicable diseases accounted for the largest proportion of admissions. Cerebrovascular diseases, hypertension, and heart failure were consistently the leading causes of hospitalization across all age groups and throughout the study period.
• Sex and Age Differences:
  • Women had higher proportions of admissions for kidney and urinary tract infections.
  • Men showed higher proportions of admissions for angina (particularly ages 45–74) and skin/soft tissue infections.
  • Admissions for asthma, pelvic inflammatory diseases, vaccine-preventable diseases, and pregnancy-related conditions declined over the study period.
• Clinical Complexity and Resource Use:
  • Pulmonary diseases and bacterial pneumonia were associated with the highest mean numbers of secondary ICD-10 diagnoses for both sexes, indicating greater clinical complexity.
  • Men generally had higher mean numbers of procedures than women, except for nutritional deficiencies, cerebrovascular diseases, and infectious gastroenteritis.
  • Gastrointestinal ulcers showed the highest mean number of procedures for both sexes.
• Length of Stay (LOS):
  • Men generally had longer average stays than women across most disease groups.
  • The longest mean LOS for men was observed in pregnancy-, childbirth-, and puerperium-related conditions (17.54 days), a category including congenital disorders.
  • For women, the longest mean LOS was for vaccine-preventable diseases and other ACSCs (13.87 days).
• Mortality and Complications:
  • Bacterial pneumonia and nutritional deficiencies were associated with the highest in-hospital mortality rates for both sexes.
  • The lowest mortality rates were found in men admitted for angina (0.77%) and women for pregnancy-related conditions (0.01%).
  • Severe healthcare-associated infections were highest in men for pregnancy-related conditions (8.33%) and nutritional deficiencies (6.99%); in women, they were highest for cerebrovascular diseases (4.85%) and heart failure (4.78%).
• Surgical vs. Medical DRGs: Men had a higher proportion of surgical DRGs across nearly all disease groups. The greatest sex difference was observed in diabetes mellitus (25.07% surgical for men vs. 14.61% for women).

Key Contributions
The paper characterizes the landscape of ACSC hospitalizations in Brazil using DRG data, providing a granular view of how these admissions vary by disease group, sex, and age. It reinforces the utility of ACSCs as a strategic indicator for assessing the performance of Primary Health Care. By linking specific disease groups to resource utilization metrics (LOS, procedures, secondary diagnoses), the study highlights the clinical complexity and economic burden associated with preventable admissions. It specifically identifies cerebrovascular diseases, hypertension, and heart failure as critical areas where PHC interventions could yield significant reductions in hospitalization rates.

Significance and Claims
The authors claim that the findings underscore the pivotal role of Primary Health Care in reducing avoidable hospitalizations and controlling healthcare costs. The high frequency of ACSC admissions, particularly for chronic NCDs, suggests weaknesses in longitudinal follow-up and care coordination within the current health network. The study posits that:

1. Indicator Value: ACSC hospitalizations serve as indirect markers of PHC capacity to provide comprehensive, continuous, and coordinated care.
2. Policy Implication: Continuous monitoring of these indicators can support the implementation of strategies to reduce admissions, optimize hospital bed management, and improve health system performance.
3. Economic Impact: Prolonged hospital stays and complex conditions associated with ACSCs impose a substantial economic burden, particularly in the context of structural underfunding in the SUS.
4. Targeted Action: The observed variations by sex and age indicate a need for targeted PHC strategies for high-risk populations.

The paper concludes that strengthening PHC is essential to ensure coordinated care and reduce avoidable hospitalizations, thereby upholding health as a fundamental social right. It acknowledges limitations, noting that the sample is restricted to hospitals using the DRG system and relies on secondary data subject to underreporting, but maintains that the findings offer valuable insights for health managers to strengthen preventive actions and continuous follow-up.