Samuel Hohmann - Academia.edu (original) (raw)

Papers by Samuel Hohmann

Liver Transplantation, 2014

A complete evaluation of living donor liver transplantation (LDLT) in the United States has been ... more A complete evaluation of living donor liver transplantation (LDLT) in the United States has been difficult because of the persistent low volume and the lack of adequate comparisons with deceased donor liver transplantation (DDLT). Recent reports have suggested outcomes equivalent to those for DDLT, but these studies did not adjust for differences in recipient selection. From a linkage between the University HealthSystem Consortium and Scientific Registry of Transplant Recipients databases, we identified 14,282 patients at 62 centers who underwent DDLT from 2007 to 2012 and 715 patients at 35 centers who underwent LDLT during the same period. Then, we performed 1:1 propensity score matching for 708 LDLT recipients based on age, Model for End-Stage Liver Disease (MELD) score, and pretransplant patient status. The median follow-up was 2 years. Compared with DDLT recipients, LDLT recipients were more likely to be white (84.5% versus 72.2%) and female (41.1% versus 31.7%), to have lower MELD scores (15 versus 19), and to be classified preoperatively as independent (65.3% versus 46.7%) and not hospitalized (91.3% versus 78.4%). The posttransplant length of stay (LOS), in-hospital mortality, costs, and survival were similar between the groups, but LDLT recipients were more likely to be readmitted within 30 days (44.9% versus 37.1%, P 5 0.001). After matching, the difference in 30-day readmission rates persisted (45.1% versus 33.8%, P 5 0.001), but there were no differences in the LOS, costs, patient survival, or graft survival. This national report shows that LDLT is associated with higher readmission rates in comparison with DDLT, but the results are comparable for other key patient metrics.

Liver International, 2015

Liver Transplantation, 2015

The rate and causes of hospital readmissions after liver transplantation (LT) remain largely unkn... more The rate and causes of hospital readmissions after liver transplantation (LT) remain largely unknown in the United States. Adult patients (n= 12,445; 43% of all LT) undergoing LT from 2007-2011 were examined with a linkage of the University HealthSystem Consortium and Scientific Registry of Transplant Recipients databases to determine incidence and risk factors for 30-day readmissions and utilization metrics at 90-days post-LT. Overall 30-day hospital readmission rate after LT was 37.9% with half of patients admitted in seven days post discharge. Readmitted patients had worse overall graft and patient survival with 2-year follow-up. Multivariable analysis identified risk factors associated with 30-day hospital readmission including higher MELD, diabetes at LT, dialysis dependent, high donor risk index allografts and discharge to rehab facility. After adjusting for donor, recipient and geographic factors in a hierarchical model, there was significant variation in readmission rates among hospitals from 26.3% to 50.8% (OR 0.53 to 1.90). In the 90-day analysis after LT, readmissions accounted for $43,785 added cost compared to patients who were not readmitted in the first 90 days. This is the first national report showing that more than one-third of LT recipients are readmitted to their center within 30 days and that readmissions were associated with center variation and increased resource utilization. This article is protected by copyright. All rights reserved.

Studies in health technology and informatics, 2015

CAPriCORN, the Chicago Area Patient Centered Outcomes Research Network, is one of the eleven PCOR... more CAPriCORN, the Chicago Area Patient Centered Outcomes Research Network, is one of the eleven PCORI-funded Clinical Data Research Networks. A collaboration of six academic medical centers, a Chicago public hospital, two VA hospitals and a network of federally qualified health centers, CAPriCORN addresses the needs of a diverse community and overlapping populations. To capture complete medical records without compromising patient privacy and confidentiality, the network created policies and mechanisms for patient consultation, central IRB approval, de-identification, de-duplication, and integration of patient data by study cohort, randomization and sampling, re-identification for consent by providers and patients, and communication with patients to elicit patient-reported outcomes through validated instruments. The paper describes these policies and mechanisms and discusses two case studies to prove the feasibility and effectiveness of the network.

Surgery, 2015

Background. The desire to provide cost-effective care has lead to an investigation of the costs o... more Background. The desire to provide cost-effective care has lead to an investigation of the costs of therapy for end-stage renal disease. Organ quality metrics are one way to attempt to stratify kidney transplants, although the ability of these metrics to predict costs and resource use is undetermined. Methods. The Scientific Registry of Transplant Recipients database was linked to the University HealthSystem Consortium Database to identify adult deceased donor kidney transplant recipients from 2009 to 2012. Patients were divided into cohorts by kidney criteria (standard vs expanded) or kidney donor profile index (KDPI) score (<85 vs 85+). Length of stay, 30-day readmission, discharge disposition, and delayed graft function were used as indicators of resource use. Cost was defined as reimbursement based on Medicare cost/charge ratios and included the costs of readmission when applicable.

Thyroid, 2015

Background: The objective of this study was to describe national trends in robotic thyroid surger... more Background: The objective of this study was to describe national trends in robotic thyroid surgery from 2009 through 2013. Methods: The University HealthSystem Consortium (UHC) database was searched for patients undergoing robotic thyroidectomy (RT) from 2009 through 2013. Another U.S. institution's RT data, not included in the UHC database, were also evaluated. Patient demographics, institutional volume, comorbid conditions, complications, and cost information were analyzed. Results: Sixty-one institutions performed 484 RT during the study period. From 2009 through 2011, U.S. annual RT volume increased from 39 cases to 140. Annual volume dropped to 69 cases in 2012 and 93 cases in 2013. Higher-volume centers reported lower complication rates ( p < 0.02). Hematoma formation (3.7%) was the most common complication, and there was one death. More than 10% of patients were obese. Brachial plexus injury and axillary skin flap perforations were reported in <1% of cases. Mean cost for a total RT was 13,287(13,287 (13,287(5,125-42,444). Conclusions: From 2009 through early 2011, there was a steady increase in RT volume, especially among highvolume institutions. In mid-to-late 2011, there was a noticeable drop in RT volume, which significantly altered the projected trajectory of the procedure in this country. Despite higher complication rates, lower-volume centers perform the majority of RT and are also responsible for recent increases in RT utilization patterns in the United States.

Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery, Jan 5, 2015

To assess hospital- and physician-level variation in pattern of perioperative antibiotic use for ... more To assess hospital- and physician-level variation in pattern of perioperative antibiotic use for laryngectomy and the relationship between pattern of antibiotic use and surgical site infection (SSI), wound dehiscence, and antibiotic-induced complications. Retrospective analysis of University HealthSystem Consortium data. Academic medical centers and affiliated hospitals. Elective admissions for laryngectomy from 2008 to 2011 and associated 30-day readmissions were analyzed with multivariate logistic regression models. There were 439 unique antibiotic regimens (agents and duration) identified over the first 4 days of the 1865 admissions included in this study. Ampicillin/sulbactam, cefazolin + metronidazole, and clindamycin were the most common agents given on the day of surgery. Clindamycin was independently associated with higher odds of SSI (odds ratio [OR] = 3.87, 95% confidence interval [CI] = 2.31-6.49]), wound dehiscence (OR = 3.42, 95% CI = 2.07-5.64), and antibiotic-induced ...

Surgery, Jan 29, 2015

Hospital readmissions are a quality indicator in bariatric surgery. In recent years, duration of ... more Hospital readmissions are a quality indicator in bariatric surgery. In recent years, duration of stay after bariatric surgery has trended down greatly. We hypothesized that a shorter postoperative hospitalization does not increase the likelihood of readmission. The University HealthSystem Consortium (UHC) is an alliance of academic medical centers and affiliated hospitals. The UHC's clinical database contains information on inpatient stay and returns (readmissions) up to 30 days after discharge. A multicenter analysis of outcomes was performed by the use of data from the January 2009 to December 2013 for patients 18 years and older. Patients were identified by bariatric procedure International Classification of Diseases, Ninth Revision, codes and restricted by diagnosis codes for morbid obesity. A total of 95,294 patients met inclusion criteria. The mean patient age was 45.4 (±0.11) years, and 73,941 (77.6%) subjects were female. There were 5,423 (5.7%) readmissions within the s...

The University HealthSystem Consortium (UHC) database was interrogated to generate a descriptive ... more The University HealthSystem Consortium (UHC) database was interrogated to generate a descriptive report of trends in robotic thyroidectomy in the US surrounding the announcement of FDA restrictions for the use of the robot in thyroid surgery in the fall of 2011. UHC represents 90% of non-profit academic medical centers in the US, consisting of 120 university medical centers and more than 300 of their affiliated hospitals (www.uhc.edu). UHC data is compiled from discharge summaries into a set of comparative demographic, charges, and procedural data. Data from UHC and another North American institution not included in the UHC database from 1st Q 2009 to 4th Q 2013 (a total of 20 quarters) was compiled. 484 patients undergoing robotic thyroidectomy were identified. Data on age, sex, race, insurance, comorbidities, complications, discharge status, length of stay, and ICU admission were collected. Data on outpatient discharge type, surgeon cost, OR time, and total cost, although incomple...

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2015

Existing surveillance mechanisms may underestimate the incidence of carbapenem-resistant gram-neg... more Existing surveillance mechanisms may underestimate the incidence of carbapenem-resistant gram-negative infections (CRGNIs). Although carbapenem resistance increases the risk of death, the trend in mortality over time is unknown. A retrospective cohort study was conducted at 40 academic medical centers using a discharge database to identify adult hospital admissions without cystic fibrosis in 2006-2012 and received intravenous colistin for >3 consecutive days or died during therapy (termed colistin cases). The primary outcomes were the number of colistin cases per 100,000 admissions per year and change in the hospital mortality rate over time compared with the rate of discharges to home. Secondary outcomes included median overall and intensive care unit lengths of stay. From 2006 to 2012, a total of 5011 unique patients were identified as colistin cases. The number per 100,000 admissions per year increased from 35.56 to 92.98 during the 7-year study (P < .001). The odds of in-h...

Infection Control & Hospital Epidemiology, 2015

The performance of a hospital- and community-onset Clostridium difficile infection definition usi... more The performance of a hospital- and community-onset Clostridium difficile infection definition using administrative data with a present-on-admission indicator was compared with definitions using clinical surveillance. For hospital-onset C. difficile infection, there was moderate sensitivity (68%) and high specificity (93%); for community-onset, sensitivity and specificity were high (both 85%). Infect Control Hosp Epidemiol 2015;00(0): 1-3.

Surgery, 2014

Hypothermia occurs in as many as 7% of elective colorectal operations and is an underestimated ri... more Hypothermia occurs in as many as 7% of elective colorectal operations and is an underestimated risk factor for complications and death. Rewarming of hypothermic patients alone is not sufficient to prevent such adverse events. We investigated the outcomes of patients who became hypothermic (&amp;amp;amp;amp;amp;lt;35°C) after elective operations and compared them with closely matched, nonhypothermic operative patients to better define the impact of hypothermia on surgical outcomes, as well as to identify independent risk factors for hypothermia. We queried the University HealthSystem Consortium (UHC) database for elective operative patients who became unintentionally hypothermic from October 2008 to March 2012, and identified 707 patients. Exclusion criteria were deliberate hypothermia, age &amp;amp;amp;amp;amp;lt;18 years, or death on day of admission. Separately, to validate the accuracy of hypothermia coding, we reviewed the hospital charts of all University of Louisville Hospital patients with hypothermia whose data were submitted to UHC. All patients from UHC with a code for hypothermia were indeed unintentionally hypothermic. Hypothermic patients undergoing elective operations experienced a 4-fold increase in mortality (17.0% vs 4.0%; P &amp;amp;amp;amp;amp;lt; .001) and a doubled complication rate (26.3% vs 13.9%; P &amp;amp;amp;amp;amp;lt; .001), in which sepsis and stroke increased the most. Several independent risk factors for hypothermia were amenable to preoperative improvement: anemia, chronic renal impairment, and unintended weight loss. Severity of illness on admission, age &amp;amp;amp;amp;amp;gt;65 years, male sex, and neurologic disorders also were risk factors. Hypothermia is associated with an increased rate of mortality and complications. Preventive treatment of these risk factors before operation and aggressive warming measures in the &amp;amp;amp;amp;amp;quot;at risk&amp;amp;amp;amp;amp;quot; population may decrease hypothermia-related morbidity and mortality in elective operations. Randomized-controlled trials should be conducted to evaluate the impact of aggressive warming measures in the at-risk population.

JAMA, 2015

Programs that analyze and report rates of surgical complications are an increasing focus of quali... more Programs that analyze and report rates of surgical complications are an increasing focus of quality improvement efforts. The most comprehensive tool currently used for outcomes monitoring in the United States is the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP). To compare surgical outcomes experienced by patients treated at hospitals that did vs did not participate in the NSQIP. Data from the University HealthSystem Consortium from January 2009 to July 2013 were used to identify elective hospitalizations representing a broad spectrum of elective general/vascular operations in the United States. Data on hospital participation in the NSQIP were obtained through review of semiannual reports published by the ACS. Hospitalizations at any hospital that discontinued or initiated participation in the NSQIP during the study period were excluded after the date on which that hospital&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s status changed. A difference-in-differences approach was used to model the association between hospital-based participation in NSQIP and changes in rates of postoperative outcomes over time. Hospital participation in the NSQIP. Risk-adjusted rates of any complications, serious complications, and mortality during a hospitalization for elective general/vascular surgery. The cohort included 345,357 hospitalizations occurring in 113 different academic hospitals; 172,882 (50.1%) hospitalizations were in NSQIP hospitals. Hospitalized patients were predominantly female (61.5%), with a mean age of 55.7 years. The types of procedures performed most commonly in the analyzed hospitalizations were hernia repairs (15.7%), bariatric (10.5%), mastectomy (9.7%), and cholecystectomy (9.0%). After accounting for patient risk, procedure type, underlying hospital performance, and temporal trends, the difference-in-differences model demonstrated no statistically significant differences over time between NSQIP and non-NSQIP hospitals in terms of likelihood of complications (adjusted odds ratio, 1.00; 95% CI, 0.97-1.03), serious complications (adjusted odds ratio, 0.98; 95% CI, 0.94-1.03), or mortality (adjusted odds ratio, 1.04; 95% CI, 0.94-1.14). No association was found between hospital-based participation in the NSQIP and improvements in postoperative outcomes over time within a large cohort of patients undergoing elective general/vascular operations at academic hospitals in the United States. These findings suggest that a surgical outcomes reporting system does not provide a clear mechanism for quality improvement.

American Journal of Perinatology, 2015

American journal of medical quality : the official journal of the American College of Medical Quality, Jan 9, 2014

This study sought to characterize variations in severe sepsis mortality between hospitals in the ... more This study sought to characterize variations in severe sepsis mortality between hospitals in the United States. Hospital discharge data (2012) were used from the University HealthSystem Consortium (UHC), a cooperative of US not-for-profit academic medical centers and affiliated hospitals. Discharge diagnosis codes were used to define severe sepsis as the presence of a serious infection with at least 1 organ dysfunction on hospital presentation. Expected mortality was determined from UHC risk adjustment mortality models. Among the 188 hospitals in the analysis, there were 256 509 patients with severe sepsis on admission. The median number of severe sepsis cases per hospital was 1202 (interquartile range [IQR] = 718-1940). Severe sepsis observed mortality (median = 8.6%; IQR = 6.8%-10.3%; range = 0.9%-18.2%) and observed-to-expected (O:E) mortality ratios (median = 0.91; IQR = 0.77-1.05; range = 0.16-1.95) varied across the hospitals. Variations in institutional severe sepsis observed...

Clinical Gastroenterology and Hepatology, 2014

Previous studies have reported that patients of higher socioeconomic status (SES) have increased ... more Previous studies have reported that patients of higher socioeconomic status (SES) have increased access to liver transplantation and reduced waitlist mortality than patients of lower SES. However, little is known about the association between SES and outcomes after liver transplantation.

Journal of Gastrointestinal Surgery, 2014

Esophagectomy is a high-risk surgical procedure. As the population ages, more elderly candidates ... more Esophagectomy is a high-risk surgical procedure. As the population ages, more elderly candidates are being evaluated for esophagectomy. The effects of patient age on outcomes after esophagectomy need to be evaluated. We identified all nonemergent esophagectomies in patients at least 18 years of age within the University HealthSystems Consortium Clinical Database/Resource Manager from 2009 to 2012. Using univariate and multivariate methods, the impact of increasing age on outcomes was analyzed. Additionally, propensity scoring was used to match patients to further investigate the effect of age on the stated outcomes. Increasing age is associated with increased mortality (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001), length of stay (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001), discharge to rehabilitative care (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001), and cost (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). The effects of age on mortality (8.0 vs 4.2 %, p = 0.03) and discharge to rehabilitative care (44.1 vs 23.4 %, p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) were confirmed using propensity scoring, comparing patients above 80 with those age 70-79. Increasing age has a significant impact on outcomes following esophagectomy, particularly mortality and discharge disposition. Compared to patients under age 80, patients at least 80 years of age considering esophagectomy should be recognized as a high-risk cohort, and these patients must be carefully risk-stratified, counseled, and selected for surgical intervention to prevent unnecessary hospitalization and mortality.

Transfusion, 2014

Although there is significant variability in the rate of blood transfusion in surgical patients, ... more Although there is significant variability in the rate of blood transfusion in surgical patients, the role of surgical skill as a determinant of blood use is unknown. We examined the association between surgery resident participation and intraoperative blood transfusion, and 30-day mortality and complications, among 381,036 patients undergoing noncardiac surgery, adjusting for patient factors and procedure complexity. Compared to attending surgeons working without a resident, cases in which the attendings worked with either Postgraduate Year (PGY) 3 to 4 resident or a PGY5 to 8 resident had a 56% (adjusted odds ratio [AOR], 1.56; 95% confidence interval [CI, 1.48-1.64) or a 78% (AOR, 1.78; 95% CI, 1.70-1.87) higher odds of receiving a blood transfusion, respectively. Involvement of surgical interns or junior residents (PGY1-2), whose role in the operative procedure is assumed to be limited, was associated with a 27% higher odds of receiving a blood transfusion (AOR, 1.27; 95% CI, 1.18-1.37). Overall, resident involvement was not associated with increased risk of 30-day mortality (AOR, 0.97; 95% CI, 0.91-1.04), but was associated with a slightly increased risk of complications (AOR, 1.13; 95% CI, 1.10-1.16). Senior surgery resident participation in noncardiac surgery is associated with between a 56% to 78% higher risk of receiving a blood transfusion intraoperatively compared to attending surgeons working without a resident. Assuming that senior surgical trainees are performing critical parts of the operative procedure and are less skilled than attending surgeons, the findings from this exploratory study suggest that intraoperative blood transfusion may serve as an indirect measure of surgical technical quality.

Otolaryngology -- Head and Neck Surgery, 2013

ABSTRACT To compare the cost of same-day vs 23-hour observation outpatient thyroidectomy at US ac... more ABSTRACT To compare the cost of same-day vs 23-hour observation outpatient thyroidectomy at US academic medical centers. Cross-sectional analysis of a national database. The University HealthSystem Consortium (UHC) data collected from discharge summaries. Discharge data were collected from the first quarter of 2009 through the second quarter of 2013. The UHC database, compiled from more than 200 affiliated hospitals, was searched based on diagnosis codes for outpatient thyroid procedures. Cost data, calculated based on reported charges, were collected in addition to demographics. Comparisons were made between same-day vs 23-hour observation based on cost. Additional stratification was performed based on the extent of thyroidectomy. During the study period, 49,936 outpatient thyroidectomies were performed. Overnight observation (63%) was more common than same-day discharge (37%). The overall mean cost of outpatient thyroidectomy was 5617,withameancostofsame−daysurgeryof5617, with a mean cost of same-day surgery of 5617,withameancostofsame−daysurgeryof4642 compared with $6101 for overnight observation (P < .0001). When stratifying by extent of thyroidectomy, the cost of same-day surgery was consistently lower than that for overnight observation. Outpatient thyroidectomy is commonly performed in the United States. It is most commonly performed on a 23-hour overnight observation basis. Overnight stay and complications were chief among other factors associated with higher cost, independent of the type of thyroid procedure performed. In appropriately selected patients, same-day thyroidectomy is a safe and cost-effective alternative to overnight observation or inpatient thyroid procedures.

Journal of Surgical Research, 2014

The University HealthSystem Consortium Clinical Database-Resource Manager (UHC CD-RM) is an admin... more The University HealthSystem Consortium Clinical Database-Resource Manager (UHC CD-RM) is an administrative database increasingly queried for both research and administrative purposes, but it has not been comprehensively validated. To address this knowledge gap, we compared the UHC CD-RM with an institutional dataset to determine its validity and accuracy. Age, gender, and date of operation were used to identify patients undergoing pancreaticoduodenectomy from 2009-2011 in both the UHC CD-RM and our institutional pancreatic surgery database. Patient- and intervention-specific variables including perioperative mortality, complications, length of stay, discharge disposition, and readmission were compared between datasets. A total of 107 UHC CD-RM and 105 institutional patients met inclusion criteria. In both datasets 103 matched cases were present. Between the 103 matched cases, there was concordance with respect to median age (P = 0.87), gender (P = 0.89), race (P = 0.84), overall length of stay (P = 0.46), discharge disposition (P = 0.95), 30-d readmission rate (P = 0.87), and 30-d mortality (P = 0.70). Most comorbidities and complications were captured; however, several disease-specific complications were absent within the UHC CD-RM. Most of the clinically significant patient- and intervention-specific variables within the UHC CD-RM are reliably reported. With recognition of its limitations, the UHC CD-RM is a reliable surrogate for institutional medical records and should be considered a valuable research tool for health service researchers.