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Implementation of the Affordable Care Act: A Comparison of Outcomes in Patients With Severe Sepsis and Septic Shock Using the National Inpatient Sample*

Chinai, Brian DO1; Gaughan, John PhD, MBA2,3; Schorr, Christa DNP, MSN, RN2,3

Author Information
doi: 10.1097/CCM.0000000000004310



Sepsis is the most common and costly diagnosis in U.S.’ hospitals, accounting for more than $20 billion of the healthcare cost in 2011 and increasing to $24 billion in 2013 (1,2). In patients with a diagnosis code of sepsis, reported overall mortality was 12.5% and varied by severity (5.6%, 14.9%, and 34.2%) for those without organ dysfunction, severe sepsis, and septic shock (3). Similarly, hospital costs increased with disease severity to $16,324, $24,638, and $38,298, respectively (3). The prevalence of sepsis is also rising, likely reflecting an aging patient population with chronic health conditions along with better sepsis recognition and documentation with appropriate sepsis coding (4). Severe sepsis and septic shock research and quality improvement programs have advanced care, resulting in decreased in-hospital mortality over the past 20 years (5–9). Despite these advances, sepsis accounts for greater than 50% of all hospital deaths, with mortality rising as disease severity increases (10,11). Great strides to improve management are ongoing, yet disparities exist that can influence outcomes.

A key modifier of outcomes is access to care due to lack of health insurance. A retrospective study of uninsured individuals with severe sepsis found that these patients were more likely to have significant disease on hospital presentation, more organs failing, and greater all-cause mortality (12). It is unclear whether these findings were due to hospital variation or access to sepsis care differences in insured versus uninsured individuals. Data demonstrate that uninsured patients partake in preventative health services less often, delay seeking care, and have worse outcomes (12,13). As reducing sepsis morbidity and mortality hinges on early recognition and intervention, the lack of insurance coverage may be a significant roadblock in seeking healthcare, ultimately resulting in poor patient outcomes (14,15).

The Affordable Care Act (ACA) was passed in 2010 to expand access to health insurance coverage, to protect patients from subjective actions by insurance companies, and to reduce cost (16). Provisions included prescription drug discounts, free preventive care for senior citizens, and increased access to home and community services. The year 2014 brought medicaid expansion, the individual mandate, the first individual exchange period, protections for no pre-existing condition exclusions, and no annual limits (17,18).

Full implementation of the ACA occurred in January 2014 (16). More than 30 million Americans were expected to have access to insurance as a result of the ACA (16). The main drivers of increased insurance coverage were increases in medicaid eligibility, tax credits for private health coverage purchased through health insurance exchanges, and the ability for young adults to remain dependents on their parents’ health insurance until age 26 (19). One study estimated that the ACA reduced the uninsured rate by 44%, decreased the number of patients without a primary care doctor by 12%, reduced those not having an annual check-up by 10%, and decreased those that forego care because of cost by 28% (20).

Several states expanded medicaid for low income adults from 1997 to 2007, reducing mortality by 6.1%, while improving coverage, access to care, and self-reported health (21). Uninsured patients, 18–64 years old, hospitalized from 2000 to 2008 with severe sepsis had a higher mortality than insured individuals (12). Ideally, increasing access to health insurance should improve access to healthcare whereby insured patients may seek care earlier, contributing to a decrease in both morbidity and mortality. The purpose of this study was to use a large national database to evaluate if implementation of the ACA contributed to improved outcomes in patients with severe sepsis or septic shock.


Data Source

Data were obtained from the Healthcare Cost and Utilization Project National Inpatient Sample (NIS) between 2011 and 2016. The NIS is the largest publicly available all-payer inpatient healthcare database, containing data that estimate approximately 35 million hospitalizations. It allows researchers to make national estimates of healthcare utilization, costs, access, quality, and outcomes. The NIS uses approximate weights to approximate a sample of all discharges from U.S. hospitals, excluding only rehabilitation and acute long-term care institutions (22). This study was examined and deemed exempt from formal review by the Institutional Review Board at Cooper University Hospital.

Study Population

Patients included in this study were between the ages of 18 and 64, with an International Classification of Diseases, 9th Edition (ICD-9) or International Classification of Diseases, 10th Edition (ICD-10) discharge diagnosis code for severe sepsis or septic shock. We aligned the ICD-9 and ICD-10 codes to a previously published study using an administrative database and also used the ICD-9 to ICD-10 crosswalk (12,23). Patients 65 years old and older, or with end-stage renal disease or solid organ transplant, were excluded, since we were interested in evaluating those other than the standard medicare population. However, patients under age 65 receiving medicare for a multitude of reasons (i.e. psychiatric, disability etc.) were included in this study.

Definition of Variables

Data were divided into two groups: 2011–2013 (pre ACA) and 2014–2016 (post ACA). These time periods were selected as the ACA was considered to be fully operational by 2014, thereby allowing a before and after comparison. Patient variables included age, sex, race, median income, primary payer, and infection source categorized by organ system. Appendix 4 (Supplemental Digital Content 1, lists the ICD-9 and ICD-10 codes for infection source.

Hospital characteristics, including hospital region, size, teaching status, and ownership were evaluated. The Elixhauser comorbidity software was used to identify the severity of comorbid conditions to generate an index score (24). Admission source was categorized as transfer from an acute care hospital, transfer from another healthcare facility (i.e. nursing home), and not transferred.

Outcome Measures

The primary outcomes of interest were in-hospital mortality and hospital length of stay (LOS). Secondary outcomes included organ failure, treatments thought to indicate severity of sepsis care (blood transfusion, tracheostomy, and mechanical ventilation), and discharge disposition. Appendix 5 (Supplemental Digital Content 1, contains diagnostic and procedural codes used to assess these secondary outcomes. Discharge disposition was classified as routine, home healthcare, transfer to acute care hospitals, transfer to other healthcare facilities (i.e. inpatient rehabilitation, skilled nursing facilities, psychiatric hospitals, intermediate care, or inpatient hospice), and other (i.e. discharged against medical advice).

Statistical Analysis

Data analyses were carried out on raw NIS data without discharge weights since national estimates are not presented. Categorical variables were compared using chi-square and linear models with binomial or multinomial outcomes and follow-up pairwise comparisons. Continuous variables were compared using t tests and analysis of variance with follow-up pairwise comparisons with Bonferroni corrections performed. A hierarchical multiple variable logistic regression was completed with mortality as the outcome. Factors included participating hospital, risk factors per time period (2011–2013 vs 2014–2016), Elixhauser comorbidity index, age, and hospital region. Statistical analysis was carried out using SAS v9.4 (SAS Institute, Cary, NC).



Between the years 2011 and 2016, a total of 361,323 severe sepsis or septic shock hospital discharges were identified. Of these, 159,133 patient discharges occurred during 2011–2013 and 202,190 during 2014–2016. In both the pre- and post-ACA groups, severe sepsis and septic shock patients were more likely to be older, male, of white race, and have a lower annual income (Table 1). In the pre-ACA period, patients were more likely to be insured by medicare or private insurance, followed by medicaid. Post ACA, there was a 53% increase in Medicaid patient discharges with an observed decrease in Medicare.

Demographic Characteristics of Patients Admitted for Severe Sepsis or Septic Shock Comparing Pre Affordable Care Act versus Post Affordable Care Act

Clinical Characteristics

The most common source of infection pre and post ACA was the respiratory system (Table 2). A marked increase in urinary tract infections was observed in the post-ACA period. In both groups, the majority of patients presented directly to the admitting hospital, followed by transfer from an acute care hospital and presentation from another health facility. The Elixhauser Comorbidity Index score, mean (sd), was 4.2 (2.0) pre ACA and 3.2 (2.5) post ACA.

Clinical Characteristics of Patients With Severe Sepsis or Septic Shock Comparing Pre Affordable Care Act Versus Post Affordable Care Act

Hospital Characteristics

Patients were admitted more often to private, nonprofit institutions in both pre- and post-ACA groups (Appendix 1, Supplemental Digital Content 1, Comparing pre- with post-ACA, there was an increase in presentation to small and urban teaching hospitals. Geographically, fewer patients with severe sepsis or septic shock presented to hospitals in the Northeast during 2014–2016 as compared to 2011–2013, with the reverse seen in the West, Midwest, and South.


Primary Outcomes.

In-hospital mortality in patients admitted with severe sepsis or septic shock was 22.9% pre-ACA compared with 18.6% post-ACA (p < 0.0001) (Table 3). Mortality stratified by region and year are seen in Appendices 2 and 3 (Supplemental Digital Content 1, During 2011–2013, the average LOS was 13.9 (17.4) days, compared with 12.4 (15.8) days during 2014–2016. After stratifying LOS according to mortality, there was a significant difference in LOS among survivors, mean, se (1.8; se = 0.06; p < 0.0001), and nonsurvivors (1.0, se = 0.09; p < 0.0001). Mortality among medicaid patients decreased by 5% post ACA.

Primary and Secondary Outcomes

Secondary Outcomes.

Comparing pre- with post-ACA, there was a decrease in the frequency of pulmonary, hepatic, and hematologic organ failure (Table 3). An increased occurrence rate of metabolic and neurologic failure was observed in the post-ACA period. Patients underwent fewer blood transfusions post ACA and were less likely to require mechanical ventilation. Conversely, more patients underwent tracheostomy post ACA. Changes in discharge disposition were observed with an increase in routine discharges post ACA and those discharged home with home care. Conversely, fewer patients were discharged to a facility or transferred to another hospital post ACA.

LOS and mortality comparisons stratified by insurance type are included in Figures 1 and 2. In the pre-ACA group, uninsured patients had the highest mortality rate. In the post-ACA group, the other category had the highest mortality, followed by uninsured patients. Mortality benefit pre versus post ACA remained after adjustment for age and Elixhauser comorbidity index (odds ratio, 1.2; CI, 1.2–1.3 [p < 0.001]).

Figure 1.
Figure 1.:
Mortality rate based on insurance type, comparing pre-Affordable Care Act (ACA) and post-ACA (p < 0.0001).


Due to study limitations including secondary analysis of a dataset, we cannot definitively establish a causal relationship between the full implementation of the ACA and improved outcomes in severe sepsis and septic shock. Despite this, to our knowledge, this is the first study evaluating the ACA’s effect on insurance coverage and how it pertains to severe sepsis and septic shock outcomes.

In this cohort, there was an approximate 4.5% reduction in in-hospital severe sepsis and septic shock mortality after full implementation of the ACA. When stratified according to insurance type, there were decreased mortality rates for patients with medicaid, private insurance, and the uninsured, with the greatest reduction identified in the medicaid population. Although uninsured patients had decreased mortality, that cohort still had a higher mortality rate when compared with individuals with medicaid or private insurance. Our findings are consistent with the available literature suggesting that uninsured patients have a higher sepsis-related mortality (12,25,26).

This study also demonstrated a post-ACA reduction in LOS, with the greatest reduction among insured patients observed in the medicaid population. Yet, this group still had a higher LOS than the uninsured population during both time periods. These results are also consistent with the current literature (12,26). Although the literature does not fully explain these differences, a plausible explanation may be related to uninsured patients having higher in-hospital mortality, resulting in a shorter hospital stay.

The improved outcomes in this study could partially be associated with the increase in insurance coverage associated with the ACA. Uninsured patients have worse outcomes than insured individuals due to lower use of preventative services, delay in seeking care, increased severity of illness on presentation, and additional organ failure(s) during the hospitalization (12,13,27–31). The decreased mortality may be attributed to insurance coverage allowing patients to present to the hospital and receive therapy earlier in their disease course. The Elixhauser Comorbidity Index was lower in the post-ACA population, suggesting that patients may not have had as many comorbidities at admission. Other factors contributing to improved outcomes are advances in sepsis care (32,33), decreased severity of illness (i.e. organ failure) during the hospitalization, and increased use of urban teaching hospitals for sepsis management. Even though many initiatives to improve processes in sepsis care have progressed over the years, this study is unable to determine if hospitals were adhering to sepsis guidelines and bundles or whether patients were exposed to sepsis awareness campaigns.

We observed that after full implementation of the ACA, the number of discharges home, with or without home care, increased by approximately 5%, while discharge to another facility decreased by approximately 1%. The current literature has conflicting results with one study demonstrating an increase in discharge to home (4) and another with no difference in discharge disposition (34).

Significant differences were seen post ACA in source of infection, organ failure, and procedures. The increase in urinary tract infections post ACA may be due to changes in coding or documentation leading to increased coding of severe sepsis or septic shock. Yet, we cannot be certain as this dataset cannot account for how clinicians may have documented pre ACA. An increase in metabolic and neurologic organ failure was also observed. We defined metabolic organ failure as acidosis. The 2012 Surviving Sepsis Campaign Guidelines recommended obtaining a lactate on initial presentation as a way to monitor for tissue hypoperfusion, and an elevated lactate was included in the diagnostic criteria (32,35). Similarly, we included altered consciousness for neurologic organ failure, and altered mental status was part of the diagnostic criteria, likely explaining why these data show a 6% increase (32,36).

There was a decrease in blood transfusions and mechanical ventilation in the post-ACA period. In 2012, the “Choosing Wisely Campaign” published guidelines limiting the overuse of blood product transfusion to specific circumstances (37). As to the decrease in mechanical ventilation, although it is plausible that patients who are not as sick do not require an advanced airway, another explanation for this finding is the increased use of noninvasive positive pressure ventilation as an attempt to avoid intubation (38). The observed increase in tracheostomy post ACA may be explained by recent data demonstrating that early tracheostomy improves patient comfort, enables early mobility, decreases ICU LOS, and allows for weaning for the ventilator (39).

Severe sepsis and septic shock outcomes can also depend on hospital characteristics. In a retrospective analysis assessing variability in hospital-level mortality in medicare beneficiaries admitted with severe sepsis and septic shock, the investigators found that mortality was dependent on where a patient received care (40). A nearly 12% increase in presentation to an urban, teaching institution was observed in the post-ACA group. This is noteworthy, as a recent large retrospective analysis comparing mortality in teaching versus nonteaching institutions found that patients who present to teaching institutions have lower mortality rates (41). Thus, there are other epidemiologic factors to consider in addition to insurance status when assessing severe sepsis and septic shock mortality.

This study has several limitations. First, there have been several published definitions of sepsis, severe sepsis, and septic shock, leading to variable diagnoses and interpretations among providers. Second, coding practices may differ between institutions, particularly during the transition from the ICD-9 to ICD-10 coding system in October 2015. Therefore, some of the differences we see in the post-ACA group may be attributable to the learning curve during the transition, evolving coding reliability and accuracy, and variable hospital participation (42).

There are several limitations of the NIS database, including the selection bias involved when deriving data, as seen with the varied n values. Data are also not available at the state, institution, or individual patient level. Therefore, we cannot state with certainty when each state started implementing the ACA. The NIS database also cannot distinguish multiple admissions for the same patient.

In addition, this study mostly involves numerator type data and a pretest-posttest design. This limits our ability to control for potential confounders. Finally, although insurance coverage likely plays a role in patient outcomes, multiple sepsis interventions occurring simultaneously also likely contributed to improved outcomes.


Advances in sepsis management have contributed to improved outcomes over time. Yet other factors may be associated with reduced mortality. This study adds valuable information to the existing literature regarding the effects of the ACA. Specifically, increased access to health insurance for patients with severe sepsis and septic shock may be associated with improved outcomes. Even with increases in healthcare coverage, understanding disparities in access to care and management for patients with severe sepsis and septic shock is essential as we continue to focus on healthcare equality. Additional prospective studies are needed to evaluate how access to insurance coverage affects healthcare access and outcomes. Consideration as to how hospital characteristics and resources contribute to sepsis outcomes, irrespective of insurance type, is warranted. Finally, management of severe sepsis and septic shock within populations are needed to continue the conversation in how to lessen potential differences in access to healthcare.

Figure 2.
Figure 2.:
Hospital length of stay based on insurance type, comparing pre-Affordable Care Act (ACA) and post-ACA (p < 0.0001).


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Affordable Care Act; healthcare insurance; septic shock; severe sepsis

Supplemental Digital Content

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