Hospital Revisits Within 30 Days After Conventional and Robotically Assisted Hysterectomy.

OBJECTIVES: To compare the rates of hospital readmissions, emergency department, and outpatient clinic visits after discharge for robotically assisted (RA) versus nonrobotic hysterectomy in women age 30 or more with nonmalignant conditions. DATA SOURCES: Discharges for 2011 for 8 states (CA, FL, GA, IA, MO, NE, NY, TN) (>86,000 inpatient hysterectomies) were drawn from the statewide databases of the Healthcare Cost and Utilization Project. Data from 4 of these states were used to study revisits after 29,000 outpatient hysterectomies. METHODS: Matched pairs of patients were constructed with propensity scores derived from each patient's age group, severity of illness, insurance coverage, and type of procedure. Both the full set of revisits and a set limited to diagnoses for revisits judged in other research to be related to the initial surgery (about 70% of all revisits) were analyzed. The analyses were repeated with an instrumental variables regression design. KEY RESULTS: Using the propensity score matched pairs, revisits, and specifically readmissions, after inpatient hysterectomy were greater for RA versus non-RA patients (relative risk of readmission=124%, P<0.01). Similar results were found for readmissions after outpatient hysterectomy, and readmissions after inpatient hysterectomy for the restricted set of related revisits. In the method with instrumental variables, RA was associated with an increase of 32% in the likelihood of any revisit (P<0.01). CONCLUSIONS: Using 2 different methods to control for selection, this study found higher rates of revisits among women undergoing RA versus non-RA hysterectomy for benign conditions. While selection bias cannot be ruled out completely in an observational study, the study supports broader use of revisits for analyses of outcomes of hysterectomy.

Predicting inpatient hospital payments in the United States: a retrospective analysis.

BACKGROUND: The Affordable Care Act (ACA) has increased rates of public and private health insurance in the United States. Increasing coverage could raise hospital revenue and reduce the need to shift costs to insured patients. The consequences of ACA on hospital revenues could be examined if payments were known for most hospitals in the United States. Actual payment data are considered confidential, however, and only charges are widely available. Payment-to-charge ratios (PCRs), which convert hospital charges to an estimated payment, have been estimated for hospitals in 10 states. Here we evaluated whether PCRs can be predicted for hospitals in states that do not provide detailed financial data. METHODS: We predicted PCRs for 5 payer categories for over 1,000 community hospitals in 10 states as a function of state, market, hospital, and patient characteristics. Data sources included the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases, HCUP Hospital Market Structure file, Medicare Provider of Service file, and state information from several sources. We performed out-of-sample prediction to determine the magnitude of prediction errors by payer category. RESULTS: Many individual, hospital, and state factors were significant predictors of PCRs. Root mean squared error of prediction ranged from 32 to over 100 % of the mean and varied considerably by which states were included or predicted. The cost-to-charge ratio (CCR) was highly correlated with PCRs for Medicare, Medicaid, and private insurance but not for self-pay or other insurance categories. CONCLUSIONS: Inpatient payments can be estimated with modest accuracy for community hospital stays funded by Medicare, Medicaid, and private insurance. They improve upon CCRs by allowing separate estimation by payer type. PCRs are currently the only approach to estimating fee-for-service payments for privately insured stays, which represent a sizable proportion of stays for individuals under age 65. Additional research is needed to improve the predictive accuracy of the models for all payers.

Variation in hospital inpatient prices across small geographic areas.

OBJECTIVES: To examine whether market competition may influence the difference in the inpatient price per discharge between public (Medicare) and private payers across small geographic areas. STUDY DESIGN: Retrospective multivariate analysis. METHODS: Data came from the 2006 Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (SIDs) in 162 counties from 6 states where an HCUP price-to-charge ratio (PCR) was available. The SIDs were linked with the Area Resource File, American Hospital Association Annual Survey Database, and US Census Bureau data files. Hospital inpatient prices were estimated by applying the HCUP PCR to total hospital charges. Payer-specific price comparisons were made for all discharges, an acute condition (acute myocardial infarction), and an elective condition (knee arthroplasty). Ordinary least squares models were used to examine the effect of market competition on the inpatient price per discharge by payer. RESULTS: Greater geographic variation was found in the inpatient price per discharge among private than public payers for most hospital services. Hospitals in more concentrated markets were associated with a higher price per discharge among knee arthroplasty discharges for both payers. CONCLUSIONS: Hospitals charged significantly higher prices to private than public payers. Because the payment policies from Medicare ultimately affect private payers, public policy efforts that take into consideration market-based approaches or payment reform may help to reduce price variations.

Geographic variation in cesarean delivery in the United States by payer.

BACKGROUND: The rate of cesarean delivery in the United States is variable across geographic areas. The aims of this study are two-fold: (1) to determine whether the geographic variation in cesarean delivery rate is consistent for private insurance and Medicaid (2) to identify the patient, population, and market factors associated with cesarean rate and determine if these factors vary by payer. METHODS: We used the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (SID) to measure the cesarean rate at the Core-Based Statistical Area (CBSA) level. We linked the hospitalization data to data from other national sources to measure population and market characteristics. We calculated unadjusted and risk-adjusted CBSA cesarean rates by payer. For the second aim, we estimated a hierarchical logistical model with the hospitalization as the unit of analysis to determine the factors associated with cesarean delivery. RESULTS: The average CBSA cesarean rate for women with private insurance was higher (18.9 percent) than for women with Medicaid (16.4 percent). The factors predicting cesarean rate were largely consistent across payers, with the following exceptions: women under age 18 had a greater likelihood of cesarean section if they had Medicaid but had a greater likelihood of vaginal birth if they had private insurance; Asian and Native American women with private insurance had a greater likelihood of cesarean section but Asian and Native American women with Medicaid had a greater likelihood of vaginal birth. The percent African American in the population predicted increased cesarean rates for private insurance only; the number of acute care beds per capita predicted increased cesarean rate for women with Medicaid but not women with private insurance. Further we found the number of obstetricians/gynecologists per capita predicted increased cesarean rate for women with private insurance only, and the number of midwives per capita predicted increased vaginal birth rate for women with private insurance only. CONCLUSIONS: Factors associated with geographic variation in cesarean delivery, a frequent and high-resource inpatient procedure, vary somewhat by payer. Using this information to identify areas for intervention is key to improving quality of care and reducing healthcare costs.

Association between the unemployment rate and inpatient cost per discharge by payer in the United States, 2005-2010.

BACKGROUND: Several reports have linked the 2007-2009 Great Recession in the United States with a slowdown in health care spending and decreased utilization. However, little is known regarding how the recent economic downturn affected hospital costs per inpatient stay for different segments of the population. The purpose of this study was to examine the association between changes in the unemployment rate and inpatient cost per discharge for Medicare and commercial discharges. METHODS: We used retrospective data at the Core Based Statistical Area (CBSA)-level from 46 states that contributed to the Healthcare Cost and Utilization Project State Inpatient Databases from 2005 to 2010. Unemployment data was derived from the American Community Survey. An instrumental variable two-stage least squares approach with fixed- or random-effects was used to examine the association between unemployment rate and inpatient cost per discharge by payer because of potential endogeneity. RESULTS: The marginal effect of unemployment was associated with an increase in inpatient cost per discharge for both payers. A one percentage point increase in the unemployment rate was associated with a $37 increase for commercial discharges and a $49 increase for Medicare discharges. CONCLUSIONS: We find evidence that the inpatient cost per discharge is countercyclical across different segments of the population. The underlying mechanisms by which unemployment affects hospital resource use however, might differ between payer groups.

Factors associated with adoption of robotic surgical technology in US hospitals and relationship to radical prostatectomy procedure volume.

OBJECTIVE: Robotic technology has diffused rapidly despite high costs and limited additive reimbursement by major payers. We aimed to identify the factors associated with hospitals' decisions to adopt robotic technology and the consequences of these decisions. METHODS: This observational study used data on hospitals and market areas from 2005 to 2009. Included were hospitals in census-based statistical areas within states in the State Inpatient Database that participated in the American Hospital Association annual surveys and performed radical prostatectomies. The likelihood that a hospital would acquire a robotic facility and the rates of radical prostatectomy relative to the prevalence of robots in geographic market areas were assessed using multivariable analysis. RESULTS: Hospitals in areas where a higher proportion of other hospitals had already acquired a robot were more likely to acquire one (P=0.012), as were those with more than 300 beds (P<0.0001) and teaching hospitals (P<0.0001). There was a significant association between years with a robot and the change in the number of radical prostatectomies (P<0.0001). More radical prostatectomies were performed in areas where the number of robots per 100,000 men was higher (P<0.0001). Adding a single robot per 100,000 men in an area was associated with a 30% increase in the rate of radical prostatectomies. CONCLUSIONS: Local area robot competition was associated with the rapid spread of robot technology in the United States. Significantly more radical prostatectomies were performed in hospitals with robots and in market areas of hospitals with robotic technology.

Adverse events for hospitalized medicare patients: is there a difference between HMO and FFS enrollees?

The study examines the likelihood of adverse outcomes associated with selected hospital safety events for two groups of Medicare patients: those enrolled in health maintenance organizations (HMOs) versus those enrolled in fee-for-service (FFS) insurance plans. The authors hypothesize that HMO patients may receive different qualities of hospital services and/or physician services relative to FFS patients. Based on the Healthcare Cost and Utilization Project State Inpatient Database, the authors include discharge data on all hospitalized elderly Medicare patients in Florida in 2002 and use multivariate logistic regression models with adjustments for hospital-level clusters. The findings demonstrate that, after adjusting for hospital quality, Medicare HMO patients were at higher risk of adverse outcomes than Medicare FFS patients for iatrogenic pneumothorax, accidental puncture or laceration, and postoperative respiratory failure.

Estimating inpatient hospital prices from state administrative data and hospital financial reports.

OBJECTIVE: To develop a tool for estimating hospital-specific inpatient prices for major payers. DATA SOURCES: AHRQ Healthcare Cost and Utilization Project State Inpatient Databases and complete hospital financial reporting of revenues mandated in 10 states for 2006. STUDY DESIGN: Hospital discharge records and hospital financial information were merged to estimate revenue per stay by payer. Estimated prices were validated against other data sources. PRINCIPAL FINDINGS: Hospital prices can be reasonably estimated for 10 geographically diverse states. All-payer price-to-charge ratios, an intermediate step in estimating prices, compare favorably to cost-to-charge ratios. Estimated prices also compare well with Medicare, MarketScan private insurance, and the Medical Expenditure Panel Survey prices for major payers, given limitations of each dataset. CONCLUSIONS: Public reporting of prices is a consumer resource in making decisions about health care treatment; for self-pay patients, they can provide leverage in negotiating discounts off of charges. Researchers can also use prices to increase understanding of the level and causes of price differentials among geographic areas. Prices by payer expand investigational tools available to study the interaction of inpatient hospital price setting among public and private payers--an important asset as the payer mix changes with the implementation of the Affordable Care Act.

Annual report on health care for children and youth in the United States: trends in racial/ethnic, income, and insurance disparities over time, 2002-2009.

OBJECTIVE: To examine trends in children's health access, utilization, and expenditures over time (2002-2009) by race/ethnicity, income, and insurance status/expected payer. METHODS: Data include a nationally representative random sample of children in the United States in 2002-2009 from the Medical Expenditure Panel Survey (MEPS) and a nationwide sample of pediatric hospitalizations in 2005 and 2009 from the Healthcare Cost and Utilization Project (HCUP). RESULTS: The percentage of children with private insurance coverage declined from 65.3% in 2002 to 60.6% in 2009. At the same time, the percentage of publicly insured children increased from 27.0% in 2002 to 33.1% in 2009. Fewer children reported being uninsured in 2009 (6.3%) compared to 2002 (7.7%). The most significant progress was for Hispanic children, for whom the percentage of uninsured dropped from 15.0% in 2002 to 10.3% in 2009. The uninsured were consistently the least likely to have access to a usual source of care, and this disparity remained unchanged in 2009. Non-Hispanic whites were most likely to report a usual source of care in both 2002 and 2009. The percentage of children with a doctor visit improved for whites and Hispanics (2009 vs 2002). In contrast, black children saw no improvement during this time period. Between 2002 and 2009, children's average total health care expenditures increased from $1294 to $1914. Average total expenditures nearly doubled between 2002 and 2009 for white children with private health insurance. Among infants, hospitalizations for pneumonia decreased in absolute number (41,000 to 34,000) and as a share of discharges (0.8% to 0.7%). Fluid and electrolyte disorders also decreased over time. Influenza appeared only in 2009 in the list of top 15 diagnoses with 11,000 hospitalization cases. For children aged 1 to 17, asthma hospitalization increased in absolute number (from 119,000 to 134,000) and share of discharges (6.6% to 7.6%). Skin infections appeared in the top 15 categories in 2009, with 57,000 cases (3.3% of total). CONCLUSIONS: Despite significant improvement in insurance coverage, disparities by race/ethnicity and income persist in access to and use of care. Hispanic children experienced progress in a number of measures, while black children did not. Because racial/ethnic and socioeconomic disparities are often reported as single cross-sectional studies, our approach is innovative and improves on prior studies by examining population trends during the time period 2002-2009. Our study sheds light on children's disparities during the most recent economic crisis.

Hospital utilization, costs, and mortality for adults with multiple chronic conditions, Nationwide Inpatient Sample, 2009.

OBJECTIVE: Our objective was to provide a national estimate across all payers of the distribution and cost of selected chronic conditions for hospitalized adults in 2009, stratified by demographic characteristics. ANALYSIS: We analyzed the Nationwide Inpatient Sample (NIS), the largest all-payer inpatient database in the United States. Use, cost, and mortality estimates across payer, age, sex, and race/ethnicity are produced for grouped or multiple chronic conditions (MCC). The 5 most common dyads and triads were determined. RESULTS: In 2009, there were approximately 28 million adult discharges from US hospitals other than those related to pregnancy and maternity; 39% had 2 to 3 MCC, and 33% had 4 or more. A higher number of MCC was associated with higher mortality, use of services, and average cost. The percentages of Medicaid, privately insured patients, and ethnic/racial groups with 4 or more MCC were highly sensitive to age. SUMMARY: This descriptive analysis of multipayer inpatient data provides a robust national view of the substantial use and costs among adults hospitalized with MCC.

Microsimulation of financial impact of demand surge on hospitals: the H1N1 influenza pandemic of fall 2009.

OBJECTIVE: Microsimulation was used to assess the financial impact on hospitals of a surge in influenza admissions in advance of the H1N1 pandemic in the fall of 2009. The goal was to estimate net income and losses (nationally, and by hospital type) of a response of filling unused hospital bed capacity proportionately and postponing elective admissions (a "passive" supply response). METHODS: Epidemiologic assumptions were combined with assumptions from other literature (e.g., staff absenteeism, profitability by payer class), Census data on age groups by region, and baseline hospital utilization data. Hospital discharge records were available from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample (NIS). Hospital bed capacity and staffing were measured with the American Hospital Association's (AHA) Annual Survey. RESULTS: Nationwide, in a scenario of relatively severe epidemiologic assumptions, we estimated aggregate net income of $119 million for about 1 million additional influenza-related admissions, and a net loss of $37 million for 52,000 postponed elective admissions. IMPLICATIONS: Aggregate and distributional results did not suggest that a policy of promising additional financial compensation to hospitals in anticipation of the surge in flu cases was necessary. The analysis identified needs for better information of several types to improve simulations of hospital behavior and impacts during demand surges.

Hospital cost and quality performance in relation to market forces: an examination of U.S. community hospitals in the "post-managed care era".

Managed care substantially transformed the U.S. healthcare sector in the last two decades of the twentieth century, injecting price competition among hospitals for the first time in history. However, total HMO enrollment has declined since 2000. This study addresses whether managed care and hospital competition continued to show positive effects on hospital cost and quality performance in the "post-managed care era." Using data for 1,521 urban hospitals drawn from the Healthcare Cost and Utilization Project, we examined hospital cost per stay and mortality rate in relation to HMO penetration and hospital competition between 2001 and 2005, controlling for patient, hospital, and other market characteristics. Regression analyses were employed to examine both cross-sectional and longitudinal variation in hospital performance. We found that in markets with high HMO penetration, increase in hospital competition over time was associated with decrease in mortality but no change in cost. In markets without high HMO penetration, increase in hospital competition was associated with increase in cost but no change in mortality. Overall, hospitals in high HMO penetration markets consistently showed lower average costs, and hospitals in markets with high hospital competition consistently showed lower mortality rates. Hospitals in markets with high HMO penetration also showed lower mortality rates in 2005 with no such difference found in 2001. Our findings suggest that while managed care may have lost its strength in slowing hospital cost growth, differences in average hospital cost associated with different levels of HMO penetration across markets still persist. Furthermore, these health plans appear to put quality of care on a higher priority than before.

Likelihood of hospital readmission after first discharge: Medicare Advantage vs. fee-for-service patients.

This study tests whether the likelihood of hospital readmission within 30 days of discharge is different for enrollees in Medicare Advantage plans versus the standard fee-for-service program. A key requirement is to control for self-selection into Advantage plans. The study uses statewide inpatient databases maintained by the Agency for Healthcare Research and Quality for five states in 2006. The type of Medicare coverage is known, along with an encrypted patient identifier. We identify eligible first discharges and the first readmission within 30 days. We use selected area characteristics as instrumental variables for enrollment in Advantage plans and apply a bivariate probit analysis. Descriptively, there is a slightly lower likelihood of readmission for Advantage plan enrollees. However, the Advantage plan patients are younger and less severely ill. After risk adjustment and control for self-selection, the enrollees in Advantage plans have a substantially higher likelihood of readmission. Recognizing caveats and limitations, the study supports informing Medicare beneficiaries about the rates of readmission for Advantage plans in their area. Analytical methods to adjust for self-selection into particular plans or plan types should be considered when possible.

What hospital inpatient services contributed the most to the 2001-2006 growth in the cost per case?

OBJECTIVE: To demonstrate a refined cost-estimation method that converts detailed charges for inpatient stays into costs at the department level to enable analyses that can unravel the sources of rapid growth in inpatient costs. DATA SOURCES: Healthcare Cost and Utilization Project State Inpatient Databases and Medicare Cost Reports for all community, nonrehabilitation hospitals in nine states that reported detailed charges in 2001 and 2006 (n = 10,280,416 discharges). STUDY DESIGN: We examined the cost per discharge across all discharges and five subgroups (medical, surgical, congestive heart failure, septicemia, and osteoarthritis). DATA COLLECTION/EXTRACTION METHODS: We created cost-to-charge ratios (CCRs) for 13 cost-center or department-level buckets using the Medicare Cost Reports. We mapped service-code-level charges to a CCR with an internally developed crosswalk to estimate costs at the service-code level. PRINCIPAL FINDINGS: Supplies and devices were leading contributors (24.2 percent) to the increase in mean cost per discharge across all discharges. Intensive care unit and room and board (semiprivate) charges also substantially contributed (17.6 percent and 11.3 percent, respectively). Imaging and other advanced technological services were not major contributors (4.9 percent). CONCLUSIONS: Payers and policy makers may want to explore hospital stay costs that are rapidly rising to better understand their increases and effectiveness.

Annual report on health care for children and youth in the United States: focus on trends in hospital use and quality.

OBJECTIVE: The aim of this study was to describe selected trends in hospital inpatient care for children between 2000 and 2007. STUDY DESIGN: Analysis was conducted of administrative data from annual nationwide databases of hospital discharges from the Agency for Healthcare Research and Quality's Healthcare Cost and Utilization Project, along with survey data from a nationally representative random sample of children from the Medical Expenditure Panel Survey. Hospital utilization rates and expenses, risk-adjusted rates of potentially avoidable hospitalization, and safety indicators in the hospital are calculated and tracked with established and downloadable software. RESULTS: The rate of hospital discharges for children aged 15 to 17 years declined significantly, mainly due to fewer maternity-related discharges. The leading principal conditions by age group were similar to the report for 1995 to 2000; however, the rate of admissions for skin infections doubled to 9 per 10,000. Hospital cost per discharge increased by an annual average of 4.5% per year compared with 2.6% annual growth in the gross domestic product deflator. Medicaid is increasingly important relative to private insurance as a payer for hospital care for children. The rate of potentially preventable hospitalizations for both acute and chronic conditions declined substantially (18%, adjusted for age and gender). Several measures of patient safety improved--the rates of postoperative sepsis, iatrogenic pneumothorax, and selected infections due to medical care declined by 14.2%, 17.8%, and 23.5%, respectively. However, the rate of accidental punctures and lacerations and the rate of decubitus ulcer increased by 25.6% and 34.5%, respectively. The trends in safety indicators varied somewhat by age group, income quartile of zip codes, insurance, region, and type of location without a consistent pattern. CONCLUSIONS/IMPLICATIONS: Although teenage pregnancy rates were declining, there was a worsening trend in skin infections. The latter may eventually be impacted by recent publication of new guidelines for treatment by office-based physicians. A gradually increasing role of Medicaid as a payer for hospital care for children will likely put an increasing strain on public resources in advance of the full implementation of the health insurance reforms recently enacted. The decline in potentially avoidable admissions reduces the use of the most expensive resources. For asthma and diabetes, children in the lowest income zip codes had persistently higher rates of admission, but the rate fell by one third during the period. Children in the South and West regions had substantial and significant declines in preventable admissions. Particular indicators of safety were improving, whereas others were worsening. Trends were not the same in all types of hospitals, all regions, and income categories. This is already a rich area for further research on the impact of quality improvement strategies; however, attention is needed to developing more tools to more thoroughly track quality of care for children.

Geographic variation: a view from the hospital sector.

Efforts to characterize geographic variation in health care utilization and spending have focused on patterns observed with Medicare data. The authors analyzed the Healthcare Cost and Utilization Project national all-payer data for inpatient stays to assess variation in hospitalizations by age groups and, consequently, to understand how utilization of the Medicare population may differ from the population of other payers. The authors found that the correlation between inpatient discharges and costs per capita for the Medicare-eligible population over 65 and younger age groups increased from moderate to strong with age. These findings suggest examining Medicare inpatient data alone may provide a useful but not comprehensive understanding how hospital utilization and costs vary for the total population.

Do Medicare Advantage enrollees tend to be admitted to hospitals with better or worse outcomes compared with fee-for-service enrollees?

The hospitals selected by or for Medicare beneficiaries might depend on whether the patient is enrolled in a Medicare Advantage (MA) plan. A theoretical model of profit maximization by MA plans takes into account the tradeoffs of consumer preferences for annual premium versus outcomes of care in the hospital and other attributes of the plan. Hospital discharge databases for 13 states in 2006, maintained by the Agency for Healthcare Research and Quality, are the main source of data. Risk-adjusted mortality rates are available for all non-maternity adult patients in each of 15 clinical categories in about 1,500 hospitals. All-adult postoperative safety event rates covering 9 categories of events are calculated for surgical cases in about 900 hospitals. Instrumental variables are used to address potential endogeneity of the choice of a MA plan. The key findings are these: enrollees in MA plans tend to be treated in hospitals with lower resource cost and higher risk-adjusted mortality compared to Fee-for-Service (FFS) enrollees. The risk-adjusted mortality measure is about 1.5 percentage points higher for MA plan enrollees than the overall mean of 4%. However, the rate of safety events in surgical patients favors MA plan enrollees--the rate is 1 percentage point below the average of 3.5%. These discrepant results are noteworthy and are plausibly due to greater discretion by the health plan in approving patients for elective surgery and as well as selecting hospitals for surgical patients. Emergency patients are generally excluded for the safety outcome measures. In addition, the current mortality measures may not adequately represent all surgical patients. Such caveats should be prominently highlighted when presenting comparative data. With that proviso, the study justifies informing Medicare beneficiaries about the mortality and safety outcome measures for hospitals being used by a MA plan compared to hospitals used by FFS enrollees.

Do patient safety events increase readmissions?

OBJECTIVE: Adverse safety events in the hospital could impose extra costs not only due to longer stays and corrective treatments, but also due to deaths and readmissions. The effects of safety events on readmissions have rarely been analyzed. Large, all-payer and all-diagnosis databases permit new tests. This study will simultaneously test the effects of safety events on risks of deaths and readmission. STUDY DESIGN: The population is a selection of almost 1.5 million adult surgery patients initially treated in 1088 short stay hospitals. These are patients at risk for at least 1 of 9 types of patient safety event, as specified in software in the public domain from the Agency for Healthcare Research and Quality. The main data sources are 7 statewide databases of hospitalizations in 2004, maintained by Agency for Healthcare Research and Quality's Healthcare Cost and Utilization Project. We control for many factors affecting readmission or death, particularly the severity of illness, chronic comorbidities, age, and payer group. Separate models are used for each type of safety event and a composite model is used for any safety event. PRINCIPAL FINDINGS: Among the patients at risk for any of the patient safety events, 2.6% had at least one safety event. The 3-month readmission rate was about 17% for those with no safety event, but about 25% when a safety event was recorded. The corresponding rates for readmission within 1 month were 11% and 16%. The in-hospital death rate was 1.3% with no safety event, but 9.2% with a safety event. After risk adjustment, the relative risk of readmission within 3 months was about 1.20 (P < 0.01), ranging from 1.14 to 1.56 for specific types of events. The risk-adjusted result for readmission within 1 month associated with at least one safety event was 1.17 (P < 0.01). However, the models for specific safety events gave a significantly high risk of readmission within 1 month for only 2 of the more common types of safety events. CONCLUSIONS: Hospital readmissions are one way that safety events can have costly consequences. More attention is warranted to assess the full extra cost of safety events, the factors influencing the rate of safety events, and strategies for health plans to improve incentives for safety.

Costly hospital readmissions and complex chronic illness.

People with multiple chronic conditions account for a large and disproportionate share of total health care costs. One aspect of the high cost for such patients is a relatively high number of hospital admissions per year. This study aims to clarify how the rate of hospital readmissions and hospital cost per person in a year depend on a patient's number of different chronic conditions ("complexity"), severity of illness, principal diagnosis at discharge, payer group, and other variables. We use a database of all hospital discharges for adults in six states. The number of different chronic conditions has a smoothly increasing effect on readmissions and cost per year, and there are notable differences by payer group. We offer illustrations of the potential savings from reducing total inpatient cost and readmissions in narrowly targeted populations with the most complex problems. The study's methods and descriptive data potentially could be useful for health plans and their sponsors (employers, government) when they design strategies to address the high cost of complex chronic illness.