Impact of Type of Health Insurance on Infection Rates among Young Trauma Patients

Abstract

Background:

Many studies have described the detrimental effect of lack of health insurance on trauma-related outcomes. It is unclear, though, whether these effects are related to pre-injury health status, access to trauma centers, or differences in quality of care after presentation. The aim of this study was to determine if patient and insurance type affect outcomes after trauma surgery.

Methods:

We conducted a retrospective chart review of prospectively collected data at the American College of Surgeons level 1 trauma registry in Rhode Island. All blunt trauma patients aged 18–45 observed from 2004 to 2014 were included. Patients were divided into one of four groups on the basis of their type of insurance: Private/commercial, Medicare, Medicaid, and uninsured. Co-morbidities and infections were recorded. Analysis of variance or the Mann-Whitney U test, as appropriate, was used to analyze the data.

Results:

A total of 8,018 patients were included. Uninsured patients were more likely to be male and younger, whereas the Medicare patient group had significantly fewer male patients. Rates of co-morbidities were highest in the Medicare group (28.1%) versus the private insurance (16.7%), Medicaid (19.9%), and uninsured (12.9%) groups (p < 0.05). However, among patients with any co-morbidity, there was no difference in the average number of co-morbidities between insurance groups. The rate of infection was highest in Medicaid patients (7.7%) versus private (5.6%), Medicare (6.3%), and uninsured (4.3%) patients (p < 0.05). Only Medicaid was associated with a significantly greater risk of developing a post-injury infection (odds ratio 1.6; 95% confidence interval 1.1–2.3).

Conclusion:

The presence of insurance, namely Medicaid, does not equate to diagnosis and management of conditions that affect trauma outcomes. Medicaid is associated with worse pre-trauma health maintenance and a greater risk of infection.

Numerous studies have described the detrimental effect of lack of health insurance on trauma-related outcomes [1]. For example, patients with private insurance have a lower mortality rate after traumatic brain injury [2]. It is unclear, though, whether these effects are related to pre-injury health status, access to trauma centers, or differences in quality of care after presentation. We have previously noted that undiagnosed medical co-morbidities often are the drivers of morbidity and death in uninsured patients suffering trauma [3]. However, there has been little investigation of whether various types of insurance are associated with differences in outcomes, which might be expected because different types of insurance likely affect the hospital course and outcomes after injury.

Infections occur more frequently in patients with medical co-morbidities. Infections also are associated with worse trauma outcomes [4] and may reflect long-term pre-injury health status and access to high-quality preventive care as well as to the severity of injury. Pneumonia is associated with more ventilator days, need for tracheostomy, and admission to long-term care facilities. The negative impact of infections on trauma outcomes also has been shown with intra-abdominal abscesses and urinary tract infections (UTIs) [5]. Control of co-morbidities such as diabetes mellitus before hospital presentation improves the outcomes of other acute surgical diseases, including post-operative infection. Efficiency of management of pre-injury co-morbidities and subsequent development of infections may be related to insurance status or type of insurance.

The Patient Protection and Affordable Care Act of 2010 (ACA) has expanded coverage to the uninsured through Medicaid expansion and private insurance exchanges. Despite this expansion, it is unclear whether newly insured patients with various types of insurance have similar access to or quality of healthcare. Most studies broadly characterize patient groups as insured versus uninsured or combine Medicare and Medicaid into government insurance. This makes it difficult to determine which aspects of the different types of insurance or the patients who subscribe to them are affecting outcomes after injury. The impact of the ACA is believed to be felt most by young individuals, as they are more likely to be uninsured or underinsured. Trauma is a leading cause of morbidity and death in this population, and post-injury infections may be related to pre-injury health status, health maintenance, and access to care. We hypothesized that individual insurance types will be associated with different rates of infections in young trauma patients. Further, these differences may be related to baseline patient characteristics or pre-injury management of chronic illnesses.

Patients and Methods

We conducted a retrospective chart review of prospectively collected data from the American College of Surgeons-verified level 1 trauma center registry for the state of Rhode Island. This series includes blunt trauma patients aged 18–45 years treated over a 10-year period from 2004 to 2014. Patients were excluded if they were dead on arrival or if they died in the trauma bay or immediately in the operating room. The data reviewed included demographics, co-morbidities, Injury Severity Score (ISS), and insurance status. Insurance status was based on their insurance on admission; any insurance acquired solely because of the trauma was excluded. Patients were divided into four groups according to their type of insurance: Private, Medicare, Medicaid, and uninsured. Patients with workers' compensation or Veterans Affairs healthcare plans were excluded.

Co-morbidities had been recorded in the trauma registry from information gathered at the time of presentation or during the hospital stay. Co-morbidities were divided into groups: Pulmonary, cardiac, hypertension, neurologic, mental illness, arthritis, gastro-esophageal disease, or diabetes mellitus. Note was made of both the presence of any co-morbidity and the number of co-morbidities per patient. We chose to focus specifically on diabetes mellitus, as it is a sentinel marker known to drive surgical infections. Efficiency of pre-injury control of diabetes was measured by HbA1c data collected during the hospital stay or the early need (<72 h after admission) for an insulin drip.

All infections were either clinically evident (abscess, cellulitis) or culture based (UTI, catheter, pneumonia via bronchoalveolar lavage [BAL]). The Clinical Pulmonary Infection Score (CPIS) was used as the trigger to consider the diagnosis of pneumonia. If the CPIS was >5 and the patient had clinical signs of pneumonia, bronchoscopy was performed. Pneumonia was diagnosed by BAL yielding >10,000 colony-forming units (CFU)/mL. Urinalysis (UA) was performed if UTI was suspected on the grounds of clinical judgment. If the UA was positive, culture was performed and was considered positive if there were >100,000 CFU/mL. All other infections, including surgical site infections (SSI), were diagnosed by the U.S. Centers for Disease Control and Prevention criteria and culture.

Chi-square analysis was used for categorical data, and the Mann-Whitney U or one-way analysis of variance (ANOVA) was applied to continuous data. Clinically relevant factors were considered for inclusion when constructing multivariable analyses. The φ coefficient was calculated to assess for co-linearity across factors. Multivariable logistic regression analysis was conducted for each insurance type adjusting for age, gender, ISS, and number of co-morbidities. Two types of analyses were undertaken. Initially, individual insurance types were compared against all patients in the other three insurance groups. Then comparisons were made between separate individual insurance groups. A p value of <0.05 was considered statistically significant. Full Institutional Review Board approval was obtained for the study.

Results

A total of 8,018 patients aged 18–45 years were admitted to the trauma service. Of these, 2,783 had private insurance, 564 had Medicare, 1,660 had Medicaid, and 3,011 were uninsured. The uninsured patients were the youngest (29.3 ± 0.1 y), and, as expected, Medicare patients were the oldest (33.9 ± 0.4 y)(p < 0.05). Uninsured patients had the highest ISS (11.4 ± 0.2) and Medicaid patients the lowest (9.9 ± 0.2). However, there was no difference in the Head Abbreviated Injury scores (Table 1).

Table 1.

Patient Characteristics by Insurance Type a

	Private	Medicare	Medicaid	Uninsured	p
Total	2,783	564	1,660	3,011
Age (years)	29.8 ± 0.2	33.9 ± 0.4	30.3 ± 0.2	29.3 ± 0.1	<0.05
Male gender (%)	72.2	67.9	62.7	74.8	<0.001
ISS	10.9 ± 0.2	10.5 ± 0.3	9.9 ± 0.2	11.4 ± 0.2	<0.05
Head AIS	3.1 ± 0.1	3.3 ± 0.2	3.3 ± 0.1	3.1 ± 0.1	NS

Presented as means ± standard error of the mean.

AIS = abbreviated injury score; ISS = injury severity score; NS = not significant.

Rates of co-morbidities were highest in the Medicare group (28.1%) versus private (16.7%), Medicaid (19.9%), and uninsured (12.9%)(p < 0.05). However, among patients with any co-morbidity, there was no difference in the average number of co-morbidities between insurance groups. Specifically focusing on diabetes mellitus, the rate of illness was highest in the private insurance group and lowest in the Medicaid group. However, the % HbA1c was highest in Medicaid patients (8.8%) vs private (7.7%), Medicare (7.2%), and uninsured (7.3%) patients (p < 0.05) (Table 2).

Table 2.

Rate and Average Number of Co-Morbidities among Patients by Type of Insurance

	Private	Medicare	Medicaid	Uninsured	p
Any co-morbidity (%)	16.7	28.1	19.9	12.9	<0.05
Average number of co-morbidities ± standard error of the mean	1.6 ± 0.1	1.2 ± 0.1	1.2 ± 0.1	1.4 ± 0.1	0.8
Percent with >1 co-morbidity	4.1	4.6	5.1	3.6	<0.05^b
Percent with diabetes^a	3.7	3.4	2.1	2.3	<0.05
HbA1c (%)	7.7	7.2	8.8	7.3	<0.05
Among diabetics: Percent with glucose difficult to control in hospital	60.8	68.7	66.3	58.1	<0.05

Percent of patients with diabetes mellitus and average measured HbA1c are shown along with the percentage of diabetic patients with glucose that was difficult to control in the hospital. P values were derived using analysis of variance.

For uninsured vs. others.

Overall, the rate of infections was highest in Medicaid patients (7.7%) versus private (5.6%), Medicare (6.3%), and uninsured (4.3%) (p < 0.05). Among all patients in the study, pneumonia occurred most frequently, followed by UTI. There was no difference in the rates of pneumonia, UTI, or central line-associated blood stream infection (CLABSI) across insurance groups. Medicare patients had a markedly lower rate of SSI (3%) (Table 3).

Table 3.

Infection Rate by Insurance Type

	Private	Medicare	Medicaid	Uninsured	p
Overall rate (%)	5.60	6.30	7.7	4.3	<0.05
% of total infections
Pneumonia	54	58	45	55	NS
UTI	33	33	32	20	NS
SSI	15	3	15	17	<0.05
CLABSI	2	0	1	2	NS

CLABI = central line-associated blood stream infection; NS = not significant; SSI = surgical site infection; UTI = urinary tract infection.

Adjusting for age, gender, ISS, and number of co-morbidities across all insurance groups, the presence of any co-morbidity was associated with a higher risk of infection (odds ratio [OR] 4.1; 95% confidence interval [CI] 3.2–4.9). Next, we assessed the cumulative effects of an increasing number of co-morbidities on the risk of developing an infection across each insurance type. Irrespective of the type of insurance, increasing numbers of co-morbidities were associated with an increasing risk of developing an infection per additional co-morbidity (Table 4).

Table 4.

Co-Morbidities and Risk of Infection by Insurance

Insurance	Odds ratio	95% Confidence interval
Private	1.8	1.6–2.1
Medicaid	1.6	1.4–1.9
Medicare	2	1.3–3.1
Uninsured	1.5	1.4–1.7

Multivariable analysis adjusting for age, gender, Injury Severity Score, and number of co-morbidities to assess the association between the presence of any co-morbidity and the risk of infection.

To assess the association between insurance type and infections, we initially compared each individual insurance type against all patients in the other three insurance groups. Adjusting for age, gender, ISS, and number of co-morbidities, only Medicaid was associated with a significantly greater risk of developing a post-injury infection (OR 1.6; 95% CI 1.1–2.3). Notably, uninsured patients had a lower risk of infection (OR 0.6; 95% CI 0.5–0.8). Neither private insurance nor Medicare affected the risk of infection (Table 5).

Table 5.

Effect of Insurance on Risk of Infection

Insurance	Odds ratio (95% confidence interval)
Medicaid	1.60 (1.1–2.3)
Medicare	0.99 (0.7–1.5)
Private	1.03 (0.8–1.26)
Uninsured	0.60 (0.5–0.8)

Comparisons across group as a whole, including odds ratio for the occurrence of infection, adjusting for age, gender, Injury Severity Score, and number of co-morbidities.

Next, we assessed whether the association between Medicaid and the greater risk of infection held true across comparisons between Medicaid and specific individual insurance types. Medicaid patients still had a higher risk of infection than those with private insurance (OR 1.9; 95% CI 1.5–2.5), Medicare (OR 2.01; 95% CI 1.2–3.2), and uninsured (OR2.2; 95% CI 1.7–2.9) (Table 6).

Table 6.

Effects of Medicaid vs. Other Insurance on Infection Risk

	Odds ratio (95% confidence interval)
Medicaid vs. private	1.9 (1.5–2.5)
Medicaid vs. Medicare	2 (1.2–3.2)
Medicaid vs. uninsured	2.2 (1.7–2.9)

Comparisons across group as a whole, including odds ratio for the occurrence of infection, adjusting for age, gender, Injury Severity Score, and number of co-morbidities.

Discussion

In this review of more than 8,000 injured patients aged 18–45 years old, we examined large groups of patients with a diversity of insurance types. Medicaid was associated with the highest rate of infection after injury, whereas uninsured patients had the lowest rate of infection. The rates of co-morbidities were significantly different across the insurance groups, being highest in the Medicare group. In focusing on diabetes mellitus as a marker of control of co-morbidities, Medicare patients had lower HBA1c than the other groups, and Medicaid patients had the highest HbA1c concentrations, suggesting the poorest pre-injury control of co-morbidities.

In the literature across a range of conditions, the outcome of Medicaid individuals has been variable. Our findings differ from those of Weygandt et al. [1], who demonstrated in a trauma population a lower mortality rate for patients with Medicaid in a large National Trauma Data Bank sample [4]. This finding was recognized by the authors as differing from the majority of the literature. Their study was limited by its cross-sectional nature. Also, insurance status was recorded at various times during hospitalization and was not a true measure of pre-injury insurance status. Most studies in various other medical conditions show worse outcomes in Medicaid patients than in those with other types of insurance. Medicaid patients were found to have higher infection rates after spine surgery, even higher than that of the uninsured [6]. In that single institution study of 1,532 patients, Medicaid patients had a 2.06 OR of SSI compared with other groups with Medicare, no, private/commercial, or VA insurance. Worse outcomes for Medicaid also have been described for numerous other conditions, including advanced breast cancer, perforated appendicitis, aortic aneurysm rupture, and spinal metastatic disease [7 –10]. Further, Medicaid coverage is associated with longer stays and higher costs in patients with pneumonia, myocardial infarction, or cerebrovascular accidents [11].

To explain this noted variability in Medicaid-related outcomes, we echo the sentiments of Kelz et al. that the impact of the type of insurance on surgical outcomes in general is related to three variables: Restricted access to high-quality care, greater acuity of presentation (or delay in presentation), and poorer pre-operative health with inefficient control of co-morbidities [12]. Of these variables, the first two are less relevant for our trauma population. In terms of access, Medicaid patients may be treated in hospitals that provide a lower quality of care. This is shown by Pieracci et al., who found that Medicaid patients were more likely to receive care at hospitals that provided a higher percentage of open rather than laparoscopic appendectomies [13]. However, these access effects should be lessened in trauma, where care generally is limited to verified trauma centers. Second, in terms of acuity of presentation, our blunt trauma patients are unique in that they do not have control over the severity of their injuries or the time of presentation or location. Therefore, in our study, it appears that the third factor, poorer pre-trauma health status and management of co-morbidities up to the time of trauma, are the most significant factors driving differences in infection rates.

Uninsured patients often have worse outcomes of conditions such as cancer and chronic medical illnesses. There are two common reasons patients do not have health insurance. First, there often is a lack of access to insurance because of socioeconomic factors, and second, individuals may perceive themselves to be healthy and not in need of insurance coverage. More than 5 million Americans 19–34 years of age forego health insurance, often because they believe it is an unnecessary cost. However, when the need for healthcare coverage arises because of acute disease or injury, there is a clear disparity in what coverage is available according to socioeconomic status. Also, it is possible that these individuals have undiagnosed disease that has not been managed or controlled prior to this point. Holden et al. noted that uninsured individuals utilize preventive services at a much lower rate than those with insurance [14]. In the trauma population, most studies have shown inferior outcomes for the uninsured. Children, adolescents, and adults without insurance were found to have higher rates of death [15]. Delays in treatment, less thorough diagnostic testing, and poorer understanding of healthcare practices in these patients were described as possible etiologies for these outcome differences.

Contrary to this body of literature, our group of uninsured patients had the lowest rates of infection after trauma. Our findings have been observed in other studies also. A review by Bell and Zarzaur found the lowest rate of major complications in uninsured patients in a large National Trauma Data Bank review [16]. Therefore, there may be a situation in which there is a significant group of young healthy individuals who both perceive themselves to be healthy and not in need of insurance coverage and who are in fact healthy.

Infections are significant complications that are a driver of late-phase morbidity and death across a spectrum of critically ill patients, including the trauma population. The International Nosocomial Infection Control Consortium, comprising 173 intensive care units (ICUs), noted an increase of approximately 20%–30% in crude excess deaths across a number of infections, including UTIs, ventilator-associated pneumonia (VAP), and CLABSI [17]. This has been demonstrated also both in trauma patients who were admitted to an ICU and those who were not. Specifically, even minor infections such as a UTI increase the trauma-related mortality rate. But death may not be the best measure of trauma-related outcomes. For VAP in trauma patients, the literature has conflicting results, with some studies showing higher mortality rates [18] whereas others show no increase in the mortality rate despite a high incidence of VAP [19]. We believe that infections are a marker of pre-trauma health status and disease management as much as a marker of the trauma severity. Understanding the effects of the presence of co-morbidity on trauma outcomes can be difficult, as adjusting for co-morbidities does not reflect the degree of disease management. Poorly controlled pre-trauma co-morbidities may affect post-injury immune competence [5]. With the decline in mortality rates from trauma, likely related to better peri-operative and ICU care, the rate of infection has been proposed as a better measure of differences in outcomes in trauma patients.

A major factor in the variability in outcomes after trauma is the presence of medical co-morbidities and their management. Our group has shown that undiagnosed medical co-morbidities were the driver of death in the uninsured after trauma. In that study, we found that the risk of death was unaffected by insurance status if at least one medical co-morbidity was present [3]. We chose HbA1c, as it is an easily measurable marker of co-morbidity control. We found that Medicaid patients had the highest HbA1c percentages and also the highest rate of infection.

The Patient Protection and Affordable Care Act of 2010 aims to provide coverage to many uninsured Americans and to improve coverage for the underinsured. This will be through both the expansion of Medicaid-type insurance and subsidized exchanges, which more closely resemble private insurance. At present, about half of the states have expanded Medicaid. A recent review by Hall and Lord estimates that the number of uninsured Americans will decrease from 18% to 9% of the population. Individual purchased insurance is estimated to increase from 6% to 12% and Medicaid from 11% to 15%, while employer-based insurance will decrease slightly from 49% to 47% [20]. A 2014 study by Aliu et al. used Medicaid expansion in New York State in 2001 to examine trends in referrals for common musculoskeletal procedures. They found that by five years after the expansion, significantly larger numbers of Medicaid patients were undergoing lower-extremity joint replacement, spine procedures, and treatment for extremity fractures/dislocations [21]. The major provisions of the ACA began on January 1, 2014. The actual numbers of insured Americans and the outcomes of these newly insured patients will need to be followed closely. We chose to focus on the populations most likely to be affected by the roll out of the ACA, namely younger patients. We excluded patients with insurance types less likely to be affected by the ACA such as VA coverage. It is possible that some of these newly insured healthy individuals will now shift to Medicaid and make Medicaid seem to have better outcomes than our baseline.

There are provisions in the ACA that improve payments for primary care, physician extenders, telemedicine, and team-based medical homes [20]. The key to success of the ACA will be how well these newly insured patients and existing Medicaid patients improve their health through the recognition and management of co-morbidities. Only then can this law be considered a worthwhile investment of resources. There still are concerns that although more individuals will have health insurance, there may still be disparities in health maintenance practices. This may be a result of either differences in quality or access to care or willingness of individuals to utilize the insurance and care.

A more ethereal concept that often is not addressed when discussing the impact of insurance status and medical outcomes is the self-management component. The mere presence of insurance or full access to health care does not equate to individual participation in daily health maintenance activities such as proper diet, exercise, and medication compliance. Prior efforts at instilling self-health management such as smoking cessation, gym membership, and participation in dietary programs have had poor results. Severe trauma most often affects young individuals, with the greatest impact on quality-associated life years. Further, co-morbidities such as diabetes mellitus and obesity that affect trauma outcomes, including infections, are rapidly increasing in prevalence in these same young individuals. Sadly, young individuals also are the most likely to be non-participatory in self-management. Thus, there is an opportunity for trauma outcomes to be improved if we can mobilize this large group of individuals to become more active in the management of their own health care. Further, individuals of low socioeconomic status who benefit from being offered ACA-related health coverage will still suffer from challenges, including living in food deserts and locales with limited access to outdoor exercise. The challenge is for the ACA to do more than just provide coverage.

Not all insurance is created equal. The presence of insurance in the form of Medicaid does not equate to diagnosis and management of conditions that affect trauma outcomes. Medicaid is associated with worse pre-trauma health maintenance and a higher risk of infections. Uninsured patients had the lowest rate of infections in our study. Despite the advent of the ACA, factors related to access and utilization of health care will continue to affect trauma-related infections.

Footnotes

Author Disclosure Statement

The authors have no conflicts of interest with regard to this paper.

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