Improving transitions and outcomes of sepsis survivors (I-TRANSFER): a type 1 hybrid protocol.

BACKGROUND: This protocol is based on home health care (HHC) best practice evidence showing the value of coupling timely post-acute care visits by registered nurses and early outpatient provider follow-up for sepsis survivors. We found that 30-day rehospitalization rates were 7 percentage points lower (a 41% relative reduction) when sepsis survivors received a HHC nursing visit within 2 days of hospital discharge, at least 1 more nursing visit the first week, and an outpatient provider follow-up visit within 7 days compared to those without timely follow-up. However, nationwide, only 28% of sepsis survivors who transitioned to HHC received this timely visit protocol. The opportunity exists for many more sepsis survivors to benefit from timely home care and outpatient services. This protocol aims to achieve this goal.  METHODS: Guided by the Consolidated Framework for Implementation Research, this Type 1 hybrid pragmatic study will test the effectiveness of the Improving Transitions and Outcomes of Sepsis Survivors (I-TRANSFER) intervention compared to usual care on 30-day rehospitalization and emergency department use among sepsis survivors receiving HHC. The study design includes a baseline period with no intervention, a six-month start-up period followed by a one-year intervention period in partnership with five dyads of acute and HHC sites. In addition to the usual care/control periods from the dyad sites, additional survivors from national data will serve as control observations for comparison, weighted to produce covariate balance. The hypotheses will be tested using generalized mixed models with covariates guided by the Andersen Behavioral Model of Health Services. We will produce insights and generalizable knowledge regarding the context, processes, strategies, and determinants of I-TRANSFER implementation. DISCUSSION: As the largest HHC study of its kind and the first to transform this novel evidence through implementation science, this study has the potential to produce new knowledge about the impact of timely attention in HHC to alleviate symptoms and support sepsis survivor's recovery at home. If effective, the impact of this intervention could be widespread, improving the quality of life and health outcomes for a growing, vulnerable population of sepsis survivors. A national advisory group will assist with widespread results dissemination.

Nursing facilities, food manufacturing plants and COVID-19 cases and deaths.

News outlets pointed to meatpacking plants and nursing homes as viral hotspots during the first wave of the COVID-19 pandemic in the US. In contrast to news reports, we find that retirement communities and assisted living facilities were associated with fewer cases and deaths and that skilled nursing facilities were associated with fewer cases. We find that meatpacking plants were associated with more cases and deaths as were bakeries. In contrast dairy plants were associated with fewer cases and deaths. Proactive implementation of policy measures in nursing homes and retirement facilities were beneficial. Analogous guidance was lacking for food manufacturing establishments, potentially exacerbating the spread of the virus.

Till death do us part: the effect of marital status on health care utilization and costs at end-of-life. A register study on all colorectal cancer decedents in Norway between 2009 and 2013.

BACKGROUND: Economic analyses of end-of-life care often focus on single aspects of care in selected cohorts leading to limited knowledge on the total level of care required to patients at their end-of-life. We aim at describing the living situation and full range of health care provided to patients at their end-of-life, including how informal care affects formal health care provision, using the case of colorectal cancer. METHODS: All colorectal cancer decedents between 2009 and 2013 in Norway (n = 7695) were linked to six national registers. The registers included information on decedents' living situation (days at home, in short- or long-term institution or in the hospital), their total health care utilization and costs in the secondary, primary and home- and community-based care setting. The effect of informal care was assessed through marital status (never married, currently married, or previously married) using regression analyses (negative binominal, two-part models and generalized linear models), controlling for age, gender, comorbidities, education, income, time since diagnosis and year of death. RESULTS: The average patient spent four months at home, while he or she spent 27 days in long-term institutions, 16 days in short-term institutions, and 21 days in the hospital. Of the total costs (~NOK 400,000), 58, 3 and 39% were from secondary carers (hospitals), primary carers (general practitioners and emergency rooms) and home- and community-based carers (home care and nursing homes), respectively. Compared to the never married, married patients spent 30 more days at home and utilized less home- and community-based care, but more health care services at the secondary and primary health care level. Their total healthcare costs were significantly lower (-NOK 65,621) than the never married. We found similar, but weaker, patterns for those who had been married previously. CONCLUSION: End-of-life care is primarily provided in the secondary and home-and community-based care level, and informal caregivers have a substantial influence on formal end-of-life care provision. Excluding aspects of care such as home and community-based care or informal care in economic analyses of end-of-life care provides a biased picture of the total resources required, and might lead to inefficient resource allocations.

Does Early Follow-Up Improve the Outcomes of Sepsis Survivors Discharged to Home Health Care?

BACKGROUND: There is little evidence to guide the care of over a million sepsis survivors following hospital discharge despite high rates of hospital readmission. OBJECTIVE: We examined whether early home health nursing (first visit within 2 days of hospital discharge and at least 1 additional visit in the first posthospital week) and early physician follow-up (an outpatient visit in the first posthospital week) reduce 30-day readmissions among Medicare sepsis survivors. DESIGN: A pragmatic, comparative effectiveness analysis of Medicare data from 2013 to 2014 using nonlinear instrumental variable analysis. SUBJECTS: Medicare beneficiaries in the 50 states and District of Columbia discharged alive after a sepsis hospitalization and received home health care. MEASURES: The outcomes, protocol parameters, and control variables were from Medicare administrative and claim files and the home health Outcome and Assessment Information Set (OASIS). The primary outcome was 30-day all-cause hospital readmission. RESULTS: Our sample consisted of 170,571 mostly non-Hispanic white (82.3%), female (57.5%), older adults (mean age, 76 y) with severe sepsis (86.9%) and a multitude of comorbid conditions and functional limitations. Among them, 44.7% received only the nursing protocol, 11.0% only the medical doctor protocol, 28.1% both protocols, and 16.2% neither. Although neither protocol by itself had a statistically significant effect on readmission, both together reduced the probability of 30-day all-cause readmission by 7 percentage points (P=0.006; 95% confidence interval=2, 12). CONCLUSIONS: Our findings suggest that, together, early postdischarge care by home health and medical providers can reduce hospital readmissions for sepsis survivors.

Modeling Health Care Expenditures and Use.

Health care expenditures and use are challenging to model because these dependent variables typically have distributions that are skewed with a large mass at zero. In this article, we describe estimation and interpretation of the effects of a natural experiment using two classes of nonlinear statistical models: one for health care expenditures and the other for counts of health care use. We extend prior analyses to test the effect of the ACA's young adult expansion on three different outcomes: total health care expenditures, office-based visits, and emergency department visits. Modeling the outcomes with a two-part or hurdle model, instead of a single-equation model, reveals that the ACA policy increased the number of office-based visits but decreased emergency department visits and overall spending.

The Roles of Cost and Quality Information in Medicare Advantage Plan Enrollment Decisions: an Observational Study.

BACKGROUND: To facilitate informed decision-making in the Medicare Advantage marketplace, the Centers for Medicare & Medicaid Services publishes plan information on the Medicare Plan Finder website, including costs, benefits, and star ratings reflecting quality. Little is known about how beneficiaries weigh costs versus quality in enrollment decisions. OBJECTIVE: We aimed to assess associations between publicly reported Medicare Advantage plan attributes (i.e., costs, quality, and benefits) and brand market share and beneficiaries' enrollment decisions. DESIGN, SETTING, PARTICIPANTS: We performed a nationwide, beneficiary-level cross-sectional analysis of 847,069 beneficiaries enrolling in Medicare Advantage for the first time in 2011. MAIN MEASURES: Matching beneficiaries with their plan choice sets, we used conditional logistic regression to estimate associations between plan attributes and enrollment to assess the proportion of enrollment variation explained by plan attributes and willingness to pay for quality. KEY RESULTS: Relative to the total variation explained by the model, the variation in plan choice explained by premiums (25.7 %) and out-of-pocket costs (11.6 %) together explained nearly three times as much as quality ratings (13.6 %), but brand market share explained the most variation (35.3 %). Further, while beneficiaries were willing to pay more in total annual combined premiums and out-of-pocket costs for higher-rated plans (from $4,154.93 for 2.5-star plans to $5,698.66 for 5-star plans), increases in willingness to pay diminished at higher ratings, from $549.27 (95 %CI: $541.10, $557.44) for a rating increase from 2.5 to 3 stars to $68.22 (95 %CI: $61.44, $75.01) for an increase from 4.5 to 5 stars. Willingness to pay varied among subgroups: beneficiaries aged 64-65 years were more willing to pay for higher-rated plans, while black and rural beneficiaries were less willing to pay for higher-rated plans. CONCLUSIONS: While beneficiaries prefer higher-quality and lower-cost Medicare Advantage plans, marginal utility for quality diminishes at higher star ratings, and their decisions are strongly associated with plans' brand market share.

Increased observation services in Medicare beneficiaries with chest pain.

INTRODUCTION: We examined trends in the use of observation services and the relationship between index service type (observation services, emergency department [ED] visits, inpatient stays) and both clinical outcomes and Medicare payments. METHODS: We created a yearly cohort panel of Medicare beneficiaries with chest pain. We evaluate the relationships between index service type and 30-day clinical outcomes using a multinomial logit model and between index service type and Medicare payments using generalized linear models. RESULTS: In 2009, 24% of patients with chest pain received observation services; this rose to 29% in 2011. Conversely, 20% were treated as hospital inpatients in 2009; this fell to 16% in 2011. In the adjusted analysis, the risk of 30-day return to the hospital was 7% less (95% confidence interval, 5%-8%) for those receiving observation services as compared with inpatients. Average Medicare payments ranged from $3032 for beneficiaries initially treated in the ED to $3885 for those initially treated in observation to $6545 for those initially treated as inpatients. DISCUSSION: Patients treated in observation are less likely than those treated in the ED or as inpatients to have an adverse event within 30 days. Adjusted Medicare payments, including the index stay and the subsequent 30 days, were substantially less for those treated in observation as compared with those treated as inpatients, but more than for those treated and released from the ED. Higher rates of observation service use do not appear to be negatively affecting patient outcomes and may lower costs relative to inpatient treatment.

Cost-offsets of prescription drug expenditures: data analysis via a copula-based bivariate dynamic hurdle model.

In this paper, we estimate a copula-based bivariate dynamic hurdle model of prescription drug and nondrug expenditures to test the cost-offset hypothesis, which posits that increased expenditures on prescription drugs are offset by reductions in other nondrug expenditures. We apply the proposed methodology to data from the Medical Expenditure Panel Survey, which have the following features: (i) the observed bivariate outcomes are a mixture of zeros and continuously measured positives; (ii) both the zero and positive outcomes show state dependence and inter-temporal interdependence; and (iii) the zeros and the positives display contemporaneous association. The point mass at zero is accommodated using a hurdle or a two-part approach. The copula-based approach to generating joint distributions is appealing because the contemporaneous association involves asymmetric dependence. The paper studies samples categorized by four health conditions: arthritis, diabetes, heart disease, and mental illness. There is evidence of greater than dollar-for-dollar cost-offsets of expenditures on prescribed drugs for relatively low levels of spending on drugs and less than dollar-for-dollar cost-offsets at higher levels of drug expenditures.

Understanding heterogeneity in price elasticities in the demand for alcohol for older individuals.

This paper estimates the price elasticity of demand for alcohol using Health and Retirement Study data. To account for unobserved heterogeneity in price responsiveness, we use finite mixture models. We recover two latent groups, one is significantly responsive to price, but the other is unresponsive. The group with greater responsiveness is disadvantaged in multiple domains, including health, financial resources, education and perhaps even planning abilities. These results have policy implications. The unresponsive group drinks more heavily, suggesting that a higher tax would fail to curb the negative alcohol-related externalities. In contrast, the more disadvantaged group is more responsive to price, thus suffering greater deadweight loss, yet this group consumes fewer drinks per day and might be less likely to impose negative externalities.

Association between Medicare Advantage plan star ratings and enrollment.

IMPORTANCE: The US Centers for Medicare & Medicaid Services publishes star ratings reflecting Medicare Advantage plan quality to inform enrollment decisions. OBJECTIVE: To assess the association between publicly reported Medicare Advantage plan quality ratings and enrollment. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of 2011 Medicare Advantage enrollments among 952,352 first-time enrollees and 322,699 enrollees switching plans. MAIN OUTCOME MEASURE: Association between star ratings and enrollment was modeled using conditional logit regression, controlling for beneficiary and plan characteristics. RESULTS: Among the 952,352 included first-time enrollees, a 1-star higher rating was associated with a 9.5 (95% CI, 9.3-9.6) percentage-point increase in likelihood to enroll. The highest rating available to a beneficiary was associated with a 1.9 (95% CI, 1.8-2.1) percentage-point increase in likelihood to enroll. Among the 322,699 enrollees switching plans, a 1-star higher rating was associated with a 4.4 (95% CI, 4.2-4.7) percentage-point increase in likelihood to enroll. A rating at least as high as a beneficiary's prior plan was associated with a 6.3 (95% CI, 6.0-6.6) percentage-point increase in likelihood to enroll. Star ratings were less strongly associated with enrollment for black, rural, low-income, and the youngest beneficiaries. CONCLUSION AND RELEVANCE: Medicare's 5-star rating program for Medicare Advantage is associated with beneficiaries' enrollment decisions.

Radiation Without Endocrine Therapy in Older Women With Stage I Estrogen-Receptor-Positive Breast Cancer is Not Associated With a Higher Risk of Second Breast Cancer Events.

PURPOSE: The omission of radiation therapy (RT) in older women with stage 1 estrogen-receptor-positive (ER+) breast cancer receiving endocrine therapy (ET) is an acceptable strategy based on randomized trial data. Less is known about the omission of ET with or without RT. METHODS AND MATERIALS: We analyzed surveillance, epidemiology, and end results (SEER)-Medicare data for 13,321 women age 66 years or older with stage I ER+ breast cancer from 2007 to 2012 who underwent breast-conserving surgery. Patients were classified into 4 groups: (1) ET + RT (reference); (2) ET alone; (3) RT alone; and (4) neither RT nor ET (NT). Second breast cancer events (SBCEs) were captured using the Chubak high-specificity algorithm. We used χ2 tests for descriptive statistics, multivariable multinomial logistic regression to estimate relative risk of undergoing a treatment, and multivariable, propensity-weighted competing-risks survival regression to estimate standardized hazard ratio (SHR) of SBCE. We set significance at P ≤ .01. RESULTS: Most women underwent both treatments, with 44% undergoing ET + RT, 41% RT alone, 6.6% ET alone, and 8.6% NT, but practice patterns varied over time. From 2007 to 2012, RT decreased from 49% to 30%, whereas ET alone and ET + RT increased (ET alone, 5.4%-9.6%; ET + RT, 38%-51%). Compared with patients age 66 to 69 years, patients age 80 to 85 years were more likely to receive NT (odds ratio [OR], 8.9), RT (OR, 1.9), or ET (OR, 8.8) versus ET + RT (P < .01). Three percent of subjects had an SBCE (2.2% ET + RT, 3.0% RT alone, 3.2% ET alone, 7.0% NT). Relative to ET + RT, NT and ET alone were associated with higher SBCE (NT: SHR, 3.7, P < .001; ET alone: SHR, 2.2, P = .008), whereas RT was not associated with a higher SBCE (SHR 1.21; P = .137). Clinical factors associated with higher SBCE were HER2 positivity and pT1c (SHR, 1.7; P = .006). CONCLUSIONS: Treatment with RT alone in older women with stage I ER+ disease is decreasing. RT alone is not associated with an increased risk for SBCE. By contrast, NT and ET are both associated with higher SBCE in multivariable analysis with propensity weighting. Further study of the omission of endocrine therapy in this patient population is warranted.

The impact of the State Innovation Models Initiative on population health.

In this paper, we examine the effects of the State Innovation Models Initiative (SIM) on population-level health status. SIM provided $250 million to six states in 2013 for broad delivery system reforms. We use data from the Behavioral Risk Factor Surveillance System for the years 2010-2016. Our sample is restricted to individuals ages 45 and older residing in 6 SIM and 15 control states. Treatment effects in a difference-in-difference design are estimated using a latent factor model for multiple indicators of health status. In addition to estimates for the primary sample, we obtain estimates for six subsamples based on strata of age, education, income, race and urban/rural status. We find that individuals in states that implemented SIM show significant improvements in health status. The effects of SIM are greater among older, Medicare eligible individuals, including those living in rural areas. The State Innovation Models Initiative, which provided financial incentives for states to implement health care delivery system reforms, led to population-level improvements in health status.

Medicare spending and outcomes after postacute care for stroke and hip fracture.

BACKGROUND: Elderly patients who leave an acute care hospital after a stroke or a hip fracture may be discharged home, or undergo postacute rehabilitative care in an inpatient rehabilitation facility (IRF) or skilled nursing facility (SNF). Because 15% of Medicare expenditures are for these types of postacute care, it is important to understand their relative costs and the health outcomes they produce. OBJECTIVE: To assess Medicare payments for and outcomes of patients discharged from acute care to an IRF, a SNF, or home after an inpatient diagnosis of stroke or hip fracture between January 2002 and June 2003. RESEARCH DESIGN: This is an observational study based on Medicare administrative data. We adjust for observable differences in patient severity across postacute care sites, and we use instrumental variables estimation to account for unobserved patient selection. STUDY OUTCOMES: Mortality, return to community residence, and total Medicare postacute payments by 120 days after acute care discharge. RESULTS: Relative to discharge home, IRFs improve health outcomes for hip fracture patients. SNFs reduce mortality for hip fracture patients, but increase rates of institutionalization for stroke patients. Both sites of care are far more expensive than discharge to home. CONCLUSIONS: When there is a choice between IRF and SNF care for stroke and hip fracture patients, the marginal patient is better off going to an IRF for postacute care. However, given the marginal cost of an IRF stay compared with returning home, the gains to these patients should be considered in light of the additional costs.

Risk Factors for Long-term Mortality and Patterns of End-of-Life Care Among Medicare Sepsis Survivors Discharged to Home Health Care.

Importance: Despite a growing recognition of the increased mortality risk among sepsis survivors, little is known about the patterns of end-of-life care among this population. Objective: To describe patterns of end-of-life care among a national sample of sepsis survivors and identify factors associated with long-term mortality risk and hospice use. Design, Setting, and Participants: This cohort study assessed sepsis survivors who were Medicare fee-for-service beneficiaries discharged to home health care using national Medicare administrative, claims, and home health assessment data from 2013 to 2014. The initial and final primary analyses were conducted in July 2017 and from July to August 2019, respectively. Exposures: Sepsis hospital discharge and 1 or more home health assessments within 1 week. Main Outcomes and Measures: Outcomes were 1-year mortality among all sepsis survivors and hospitalization in the last 30 days of life, death in an acute care hospital, and hospice use among decedents. Multivariate logistic regression was used to identify factors associated with 1-year mortality and hospice use. Results: Among 87 581 sepsis survivors who were Medicare fee-for-service beneficiaries discharged to home health care, 49 323 (56.3%) were aged 75 years or older, 69 499 (79.4%) were non-Hispanic white, and 48 472 (55.3%) were female. Among the total survivors, 24 423 (27.9%) people died within 1 year of discharge, with a median (interquartile range) survival time of 119 (51-220) days. Among these decedents, 16 684 (68.2%) were hospitalized in the last 30 days of life, 6560 (26.8%) died in an acute care hospital, and 12 573 (51.4%) were enrolled in hospice, with 5729 (45.6%) using hospice for 7 or fewer days. Several factors were associated with 1-year mortality, including a cancer diagnosis (odds ratio [OR], 3.66; 95% CI, 3.50-3.83; P < .001), multiple dependencies of activities of daily living or instrumental activities of daily living (OR, 2.80; 95% CI, 2.57-3.05; P < .001), and an overall poor health status (OR, 2.21; 95% CI, 2.01-2.44; P < .001) documented on home health assessment. Among the decedents, cancer was associated with hospice use (OR, 2.25; 95% CI, 2.11-2.41; P < .001), patients aged 85 years or older (OR, 1.49; 95% CI, 1.37-1.61; P < .001), and living in an assisted living setting (OR, 1.93; 95% CI, 1.69-2.19; P < .001). Conclusions and Relevance: The findings of this study suggest that death within 1 year after sepsis discharge may be common among Medicare beneficiaries discharged to home health care. Although 1 in 2 decedents used hospice, aggressive care near the end of life and late hospice referral were common. Readily identifiable risk factors suggest opportunities to target efforts to improve palliative and end-of-life care among high-risk sepsis survivors.

Provider networks and primary-care signups: do they restrict the use of medical services?

This article analyzes the effect of gatekeeper and network restrictions on use of health-care services using simulation-based estimation methods. Data from the Community Tracking Survey (1996-1997) show significant evidence of selection into plans with gatekeeper and/or network restrictions. Enrollees in plans with networks of physicians have fewer office-based visits to non-physician medical professionals, but more emergency room visits and hospital stays. Individuals in plans that require signups with a primary-care provider have more visits to non-physician providers of care, more surgeries and hospital stays but substantially fewer emergency room visits. Enrollees of plans that do not pay for out-of-network services have more office-based and emergency room visits, but less surgeries and hospitalizations.

Heterogeneity in long term health outcomes of migrants within Italy.

This article examines the long term physical and mental health effects of internal migration focusing on a relatively unique migration experience concentrated over a short period between 1950 and 1970 from the South to the North of Italy. We find a positive and statistically significant association between migration, its timing and physical health for migrant females, which we show are likely to represent rural females in both the early and the late cohort. We find less defined evidence of migration-health association for mental health. We link our findings to the economic transition and labor market transformation that Italy witnessed in that era. Male migrants were likely to be positively selected to migration, but harsh working conditions were likely to downplay this differential. On the contrary, women migrants, by and large, would not engage in the formal labor market avoiding the ill effects of working environments, at the same time benefiting from better living conditions and health care in the destination regions.

Are primary care physicians, public and private sector specialists substitutes or complements? Evidence from a simultaneous equations model for count data.

In this paper, we examine the relationships between health care visits to general practitioners, public and private sector specialists using data from Italy, which has a mixed public-private health care system. We develop a simultaneous equations model that allows for the discreteness of measures of utilization and estimate this model using maximum simulated likelihood. Once common unobserved heterogeneity is properly accounted for, general practitioners, public and private specialists are found to be substitute sources of medical care. In contrast, a naive model finds they are complements.

Isolated Involvement of Penis in Fournier's Gangrene: A Rare Possibility.

skin and subcutaneous tissue. Penis may be secondarily affected in some cases; however, primary isolated involvement of penis is rare. A 48-year male smoker presented with pain and blackish discoloration of the distal part of penis for the last 4 days which developed following rupture of a papulo-vesicular lesion over the prepuce of penis. It rapidly progressed to involve half of the skin of the penis. The patient was hospitalized and broad spectrum antibiotics were administered parenterally. Emergency wound debridement and urinary diversion by suprapubic cystostomy was done. After repeated wound debridement and dressings, the wound healed. Our case was unusual as the penis was the sole site of affection, which is very unusual and only few such cases are reported in the literature.

Secondary Surgery Versus Chemotherapy for Recurrent Ovarian Cancer.

OBJECTIVE: The best course of treatment for recurrent ovarian cancer is uncertain. We sought to determine whether secondary cytoreductive surgery for first recurrence of ovarian cancer improves overall survival compared with other treatments. MATERIALS AND METHODS: We assessed survival using Surveillance, Epidemiology and End Results-Medicare data for advanced stage ovarian cancer cases diagnosed from January 1, 1997 to December 31, 2007 with survival data through 2010 using multinomial propensity weighted finite mixture survival regression models to distinguish true from misclassified recurrences. Of 35,995 women ages 66 years and older with ovarian cancer, 3439 underwent optimal primary debulking surgery with 6 cycles of chemotherapy; 2038 experienced a remission. RESULTS: One thousand six hundred thirty-five of 2038 (80%) women received treatment for recurrence of whom 72% were treated with chemotherapy only, 16% with surgery and chemotherapy and 12% received hospice care. Median survival of women treated with chemotherapy alone, surgery and chemotherapy, or hospice care was 4.1, 5.4, and 2.2 years, respectively (P<0.001). Of those receiving no secondary treatments, 75% were likely true nonrecurrences with median survival of 15.9 years and 25% misclassified with 2.4 years survival. Survival among women with recurrence was greater for those treated with surgery and chemotherapy compared with chemotherapy alone (hazard ratio=1.67; 95% confidence interval, 1.13-2.47). Women who were older with more comorbidities and high-grade cancer had worse survival. CONCLUSIONS: Secondary surgery with chemotherapy to treat recurrent ovarian cancer increases survival by 1.3 years compared with chemotherapy alone and pending ongoing randomized trial results, may be considered a standard of care.

Spatiotemporal mapping of matrix remodelling and evidence of in situ elastogenesis in experimental abdominal aortic aneurysms.

Spatiotemporal changes in the extracellular matrix (ECM) were studied within abdominal aortic aneurysms (AAAs) generated in rats via elastase infusion. At 7, 14 and 21 days post-induction, AAA tissues were divided into proximal, mid- and distal regions, based on their location relative to the renal arteries and the region of maximal aortic diameter. Wall thicknesses differed significantly between the AAA spatial regions, initially increasing due to positive matrix remodelling and then decreasing due to wall thinning and compaction of matrix as the disease progressed. Histological images analysed using custom segmentation tools indicated significant differences in ECM composition and structure vs healthy tissue, and in the extent and nature of matrix remodelling between the AAA spatial regions. Histology and immunofluorescence (IF) labelling provided evidence of neointimal AAA remodelling, characterized by presence of elastin-containing fibres. This remodelling was effected by smooth muscle α-actin-positive neointimal cells, which transmission electron microscopy (TEM) showed to differ morphologically from medial SMCs. TEM of the neointima further showed the presence of elongated deposits of amorphous elastin and the presence of nascent, but not mature, elastic fibres. These structures appeared to be deficient in at least one microfibrillar component, fibrillin-1, which is critical to mature elastic fibre assembly. The substantial production of elastin and elastic fibre-like structures that we observed in the AAA neointima, which was not observed elsewhere within AAA tissues, provides a unique opportunity to capitalize on this autoregenerative phenomenon and direct it from the standpoint of matrix organization towards restoring healthy aortic matrix structure, mechanics and function. Copyright © 2014 John Wiley & Sons, Ltd.