Trends in Bariatric Surgery: Procedure Selection, Revisional Surgeries, and Readmissions

BACKGROUND

There are limited data quantifying national trends, post-operative readmissions, and revisional surgeries for bariatric procedures. We hypothesized that there is a trend away from Roux en Y gastric bypass (RYGB) and laparoscopic adjustable gastric bands (LAGB) in favor of vertical sleeve gastrectomies (VSG). We hypothesized that VSG was associated with fewer revisions and readmissions, and that demographics and comorbidities were associated with surgery received.

METHODS

We used the US-based Premier database, 2008-2013 and 2014 first and second quarters to 1. Examine trends in incidence of RYGB, LAGB and VSG. 2. Quantify occurrence of revisional surgeries and readmissions. 3. Identify predictors of receipt of procedure and of readmissions.

RESULTS

The proportion of VSG increased from 3.0 to 54 % from 2008 to 2014. RYGB decreased from 52 % in 2008 to 32 % by 2014. Earlier year, female sex, white race, western (versus southern) region, and Medicaid predicted receipt of RYGB. Later year, male sex, nonwhite race, northeast or western (versus southern) regions, and insurance type predicted VSG. Readmission was less likely for VSG (OR 0.72, 95 % CI 0.65-0.81), male sex (OR 0.83, 95 % CI 0.72-0.95), and more likely for black race (OR Black vs White 1.2, 95 % CI 1.1-1.4).

CONCLUSIONS

Discharge year strongly predicted surgery type. Females, whites, and Medicaid recipients received RYGB more than referents. Conversely, males, non-whites, and insured patients were more likely to receive VSG. Underinsured, regardless of surgery type, were more likely to be readmitted. These findings have important implications for health policy and cost-containment strategies.

Efficient Computation of Reduced Regression Models

We consider settings where it is of interest to fit and assess regression submodels that arise as various explanatory variables are excluded from a larger regression model. The larger model is referred to as the full model; the submodels are the reduced models. We show that a computationally efficient approximation to the regression estimates under any reduced model can be obtained from a simple weighted least squares (WLS) approach based on the estimated regression parameters and covariance matrix from the full model. This WLS approach can be considered an extension to unbiased estimating equations of a first-order Taylor series approach proposed by Lawless and Singhal. Using data from the 2010 Nationwide Inpatient Sample (NIS), a 20% weighted, stratified, cluster sample of approximately 8 million hospital stays from approximately 1000 hospitals, we illustrate the WLS approach when fitting interval censored regression models to estimate the effect of type of surgery (robotic versus nonrobotic surgery) on hospital length-of-stay while adjusting for three sets of covariates: patient-level characteristics, hospital characteristics, and zip-code level characteristics. Ordinarily, standard fitting of the reduced models to the NIS data takes approximately 10 hours; using the proposed WLS approach, the reduced models take seconds to fit.

One-Step Generalized Estimating Equations with Large Cluster Sizes

Medical studies increasingly involve a large sample of independent clusters, where the cluster sizes are also large. Our motivating example from the 2010 Nationwide Inpatient Sample (NIS) has 8,001,068 patients and 1049 clusters, with average cluster size of 7627. Consistent parameter estimates can be obtained naively assuming independence, which are inefficient when the intra-cluster correlation (ICC) is high. Efficient generalized estimating equations (GEE) incorporate the ICC and sum all pairs of observations within a cluster when estimating the ICC. For the 2010 NIS, there are 92.6 billion pairs of observations, making summation of pairs computationally prohibitive. We propose a one-step GEE estimator that 1) matches the asymptotic efficiency of the fully-iterated GEE; 2) uses a simpler formula to estimate the ICC that avoids summing over all pairs; and 3) completely avoids matrix multiplications and inversions. These three features make the proposed estimator much less computationally intensive, especially with large cluster sizes. A unique contribution of this paper is that it expresses the GEE estimating equations incorporating the ICC as a simple sum of vectors and scalars.

Radical prostatectomy innovation and outcomes at military and civilian institutions

OBJECTIVES

Limited data are available regarding the impact of the type of healthcare delivery system on technology diffusion and associated clinical outcomes. We assessed the adoption of minimally invasive radical prostatectomy (MIRP), a recent clinical innovation, and whether this adoption altered surgical morbidity for prostate cancer surgery.

STUDY DESIGN

Retrospective review of administrative data from TRICARE, the healthcare program of the United States Military Health System. Surgery occurred at military hospitals, supported by federal appropriations, or civilian hospitals, supported by hospital revenue.

METHODS

We evaluated TRICARE beneficiaries with prostate cancer (International Classification of Disease, 9th Revision, Clinical Modification [ICD-9-CM] code: 185) who received a radical prostatectomy (60.5) between 2005 and 2009. MIRP was identified based on minimally invasive surgery codes (54.21, 17.42). We assessed yearly MIRP utilization, 30-day postoperative complications (Clavien classification system), length of stay, blood transfusion, and long-term urinary incontinence and erectile dysfunction.

RESULTS

A total of 3366 men underwent radical prostatectomy at military hospitals compared with 1716 at civilian hospitals, with minimal clinic-demographic differences. MIRP adoption was 30% greater at civilian hospitals. There were fewer blood transfusions (odds ratio, 0.44; P <.0001) and shorter lengths of stay (incidence risk ratio, 0.85; P <.0001) among civilian hospitals, while 30-day postoperative complications, as well as long-term urinary incontinence and erectile dysfunction rates, were comparable.

CONCLUSIONS

Compared with military hospitals, civilian hospitals had a greater MIRP adoption during this timeframe, but had comparable surgical morbidity.

Racial Disparities in End-of-Life Care Among Patients With Prostate Cancer: A Population-Based Study

OBJECTIVE

To examine racial disparities in end-of-life (EOL) care among black and white patients dying of prostate cancer (PCa).

METHODS

Relying on the SEER-Medicare database, 3789 patients who died of metastatic PCa between 1999 and 2009 were identified. Information was assessed regarding diagnostic care, therapeutic interventions, hospitalizations, intensive care unit (ICU) admissions, and emergency department visits in the last 12 months, 3 months, and 1 month of life. Logistic regression tested the relationship between race and the receipt of diagnostic care, therapeutic interventions, and high-intensity EOL care.

RESULTS

Overall, 729 patients (19.24%) were black. In the 12-months preceding death, laboratory tests (odds ratio [OR], 0.51; 95% CI, 0.36-0.72), prostate-specific antigen test (OR, 0.54; 95% CI, 0.43-0.67), cystourethroscopy (OR, 0.71; 95% CI, 0.56-0.90), imaging procedure (OR, 0.58; 95% CI, 0.41-0.81), hormonal therapy (OR, 0.53; 95% CI, 0.44-0.65), chemotherapy (OR, 0.59; 95% CI, 0.48-0.72), radiotherapy (OR, 0.74; 95% CI, 0.61-0.90), and office visit (OR, 0.38; 95% CI, 0.28-0.50) were less frequent in black versus white patients. Conversely, high-intensity EOL care, such as ICU admission (OR, 1.27; 95% CI, 1.04-1.58), inpatient admission (OR, 1.49; 95% CI, 1.09-2.05), and cardiopulmonary resuscitation (OR, 1.72; 95% CI, 1.40-2.11), was more frequent in black versus white patients. Similar trends for EOL care were observed at 3-month and 1-month end points.

CONCLUSIONS

Although diagnostic and therapeutic interventions are less frequent in black patients with end-stage PCa, the rate of high-intensity and aggressive EOL care is higher in these individuals. These disparities may indicate that race plays an important role in the quality of care for men with end-stage PCa.

Testing for independence in J×K contingency tables with complex sample survey data

The test of independence of row and column variables in a (J×K) contingency table is a widely used statistical test in many areas of application. For complex survey samples, use of the standard Pearson chi-squared test is inappropriate due to correlation among units within the same cluster. Rao and Scott (1981, Journal of the American Statistical Association 76, 221-230) proposed an approach in which the standard Pearson chi-squared statistic is multiplied by a design effect to adjust for the complex survey design. Unfortunately, this test fails to exist when one of the observed cell counts equals zero. Even with the large samples typical of many complex surveys, zero cell counts can occur for rare events, small domains, or contingency tables with a large number of cells. Here, we propose Wald and score test statistics for independence based on weighted least squares estimating equations. In contrast to the Rao-Scott test statistic, the proposed Wald and score test statistics always exist. In simulations, the score test is found to perform best with respect to type I error. The proposed method is motivated by, and applied to, post surgical complications data from the United States' Nationwide Inpatient Sample (NIS) complex survey of hospitals in 2008.

Audit-identified avoidable factors in maternal and perinatal deaths in low resource settings: a systematic review

BACKGROUND

Audits provide a rational framework for quality improvement by systematically assessing clinical practices against accepted standards with the aim to develop recommendations and interventions that target modifiable deficiencies in care. Most childbirth-associated mortality audits in developing countries are focused on a single facility and, up to now, the avoidable factors in maternal and perinatal deaths cataloged in these reports have not been pooled and analyzed. We sought to identity the most frequent avoidable factors in childbirth-related deaths globally through a systematic review of all published mortality audits in low and lower-middle income countries.

METHODS

We performed a systematic review of published literature from 1965 to November 2011 in Pubmed, Embase, CINAHL, POPLINE, LILACS and African Index Medicus. Inclusion criteria were audits from low and lower-middle income countries that identified at least one avoidable factor in maternal or perinatal mortality. Each study included in the analysis was assigned a quality score using a previously published instrument. A meta-analysis was performed for each avoidable factor taking into account the sample sizes and quality score from each individual audit. The study was conducted and reported according to PRISMA guidelines for systematic reviews.

RESULTS

Thirty-nine studies comprising 44 datasets and a total of 6,205 audited deaths met inclusion criteria. The analysis yielded 42 different avoidable factors, which fell into four categories: health worker-oriented factors, patient-oriented factors, transport/referral factors, and administrative/supply factors. The top three factors by attributable deaths were substandard care by a health worker, patient delay, and deficiencies in blood transfusion capacity (accounting for 688, 665, and 634 deaths attributable, respectively). Health worker-oriented factors accounted for two-thirds of the avoidable factors identified.

CONCLUSIONS

Audits provide insight into where systematic deficiencies in clinical care occur and can therefore provide crucial direction for the targeting of interventions to mitigate or eliminate health system failures. Given that the main causes of maternal and perinatal deaths are generally consistent across low resource settings, the specific avoidable factors identified in this review can help to inform the rational design of health systems with the aim of achieving continued progress towards Millennium Development Goals Four and Five.

Comparative rates of adverse events with different formulations of intravenous iron

Oral iron replacement is the standard therapy in iron-deficiency anemia (IDA). However, 59% of patients have gastrointestinal toxicity. With impaired iron uptake from the gastrointestinal tract (in anemia of chronic disease (ACD) or after bariatric surgery), suboptimal responsiveness to exogenous erythropoietin (in chronic renal failure), in patients with cancer receiving chemotherapy, or when oral iron is poorly tolerated, IV iron therapy is the preferred mode of repletion. Although effective in increasing hemoglobin, the relative safety of the available IV iron preparations is not well documented. We examined the comparative safety of IV iron formulations used at hospitals associated with our institution. Among 619 unique patients who received IV iron over a 2-year period, we found 32 adverse events (AEs), ranging from urticaria to chest pain. There were no serious AEs or anaphylactic-type reactions. In a multivariate model, there was no difference in AE rates between low-molecular-weight iron dextran (LMWD) and ferric gluconate; however, iron sucrose had significantly higher odds ratio of AEs (OR = 5.7; 95% CI = 1.6–21.3). Our data suggest that AE rates with IV iron are acceptable. More widespread use of LMWD, in particular, which can be given safely as a total dose infusion (TDI), should be considered.

Receipt of appropriate surgical care for Medicare beneficiaries with cancer

OBJECTIVE

To investigate receipt of appropriate surgical care in Medicare beneficiaries with cancer.

DESIGN

Retrospective cohort study.

SETTING

National Surveillance, Epidemiology, and End Results registry linked to Medicare claims data.

PATIENTS

Fee-for-service Medicare patients aged 65 years or older who underwent a definitive surgical resection for breast, colon, gastric, rectal, or thyroid cancer diagnosed between January 2000 and December 2005. Claims data were available from January 1999 through December 2007.

MAIN OUTCOME MEASURES

Receipt of care concordant with established practice guidelines in surgical oncology in the aggregate and by hospital.

RESULTS

Concordance with guidelines was greater than 90% for 7 of 11 measures. All guidelines regarding adjuvant therapy had concordance rates greater than 90%. Only 2 of 5 measures for nodal management had concordance rates greater than 90%. At least 50% of hospitals provided guideline-concordant care to 100% of their patients for 6 of 11 guidelines. Patients receiving appropriate care tended to be younger, healthier, white, and more affluent, to have less advanced disease, and to live in the Midwest.

CONCLUSIONS

We found a high level of concordance with guidelines in some domains of surgical oncology care but far less so in others, particularly for gastric and colon nodal management. Given the current national focus on improving the quality of health care, surgeons must focus on generating data to define appropriate care and translating those data into everyday practice.

Complexity and heterogeneity: what drives the ever-changing brain in Huntington's disease?

Significant advances are being made in our understanding of basic pathophyiological and biochemical mechanisms that cause Huntington's disease (HD). There is increasing reason to believe that pathologic alterations occur in the brain for years before symptoms manifest. The "classic" hallmark of neuropathology in HD is selective neurodegeneration in which vulnerable populations of neurons degenerate while less vulnerable populations are spared. While the earliest and most striking neuropathologic changes have been found in the neostriatum, neuronal loss has been identified in many other regions of the brain. We report topologically selective, early, and progressive changes in the cortex, striatum, extrastriatal brain structures, and white matter throughout the spectrum of disease. Our growing understanding of HD underscores the reality that points to the complexity of HD. A single, well-defined, genetic mutation causes a cascade of events whose final result is an aggregate insult of the homeostatic process. We explore possible explanations for the selective vulnerability of the brain in HD. The ultimate goal in HD is to develop disease-modifying therapies that will prevent the onset of clinical symptoms in those individuals who are at risk and slow the progression of symptoms in those individuals already affected with symptoms. Understanding changes in brain morphometry and their relationship to clinical symptoms may provide important and new insights into basic pathophysiological mechanisms at play in the disease.

Disparity in outcomes of surgical revascularization for limb salvage: race and gender are synergistic determinants of vein graft failure and limb loss

BACKGROUND

Vein bypass surgery is an effective therapy for atherosclerotic occlusive disease in the coronary and peripheral circulations; however, long-term results are limited by progressive attrition of graft patency. Failure of vein bypass grafts in patients with critical limb ischemia results in morbidity, limb loss, and additional resource use. Although technical factors are known to be critical to the success of surgical revascularization, patient-specific risk factors are not well defined. In particular, the relationship of race/ethnicity and gender to the outcomes of peripheral bypass surgery has been controversial.

METHODS AND RESULTS

We analyzed the Project of Ex Vivo Vein Graft Engineering via Transfection III (PREVENT III) randomized trial database, which included 1404 lower extremity vein graft operations performed exclusively for critical limb ischemia at 83 North American centers. Trial design included intensive ultrasound surveillance of the bypass graft and clinical follow-up to 1 year. Multivariable modeling (Cox proportional hazards and propensity score) was used to examine the relationships of demographic variables to clinical end points, including perioperative (30-day) events and 1-year outcomes (vein graft patency, limb salvage, and patient survival). Final propensity score models adjusted for 16 covariates (including type of institution, technical factors, selected comorbidities, and adjunctive medications) to examine the associations between race, gender, and outcomes. Among the 249 black patients enrolled in PREVENT III, 118 were women and 131 were men. Black men were at increased risk for early graft failure (hazard ratio [HR], 2.832 for 30-day failure; 95% confidence interval [CI], 1.393 to 5.759; P=0.0004), even when the analysis was restricted to exclude high-risk venous conduits. Black patients experienced reduced secondary patency (HR, 1.49; 95% CI, 1.08 to 2.06; P=0.016) and limb salvage (HR, 2.02; 95% CI, 1.27 to 3.20; P=0.003) at 1 year. Propensity score models demonstrate that black women were the most disadvantaged, with an increased risk for loss of graft patency (HR, 2.02 for secondary patency; 95% CI, 1.27 to 3.20; P=0.003) and major amputation (HR, 2.38; 95% CI, 1.18 to 4.83; P=0.016) at 1 year. Perioperative mortality and 1-year mortality were similar across race/gender groups.

CONCLUSIONS

Black race and female gender are risk factors for adverse outcomes after vein bypass surgery for limb salvage. Graft failure and limb loss are more common events in black patients, with black women being a particularly high-risk group. These data suggest the possibility of an altered biological response to vein grafting in this population; however, further studies are needed to determine the mechanisms underlying these observed disparities in outcome.

Cerebral cortex and the clinical expression of Huntington's disease: complexity and heterogeneity

The clinical phenotype of Huntington's disease (HD) is far more complex and variable than depictions of it as a progressive movement disorder dominated by neostriatal pathology represent. The availability of novel neuro-imaging methods has enabled us to evaluate cerebral cortical changes in HD, which we have found to occur early and to be topographically selective. What is less clear, however, is how these changes influence the clinical expression of the disease. In this study, we used a high-resolution surface based analysis of in vivo MRI data to measure cortical thickness in 33 individuals with HD, spanning the spectrum of disease and 22 age- and sex-matched controls. We found close relationships between specific functional and cognitive measures and topologically specific cortical regions. We also found that distinct motor phenotypes were associated with discrete patterns of cortical thinning. The selective topographical associations of cortical thinning with clinical features of HD suggest that we are not simply correlating global worsening with global cortical degeneration. Our results indicate that cortical involvement contributes to important symptoms, including those that have been ascribed primarily to the striatum, and that topologically selective changes in the cortex might explain much of the clinical heterogeneity found in HD. Additionally, a significant association between regional cortical thinning and total functional capacity, currently the leading primary outcome measure used in neuroprotection trials for HD, establishes cortical MRI morphometry as a potential biomarker of disease progression.

Technical factors affecting autogenous vein graft failure: observations from a large multicenter trial

OBJECTIVE

The influence of operator-dependent variables on the outcomes of lower extremity bypass (LEB) surgery have primarily been reported in single-institution, retrospective studies. We utilized data from a prospective, multicenter trial to identify technical variables that were significantly associated with early and midterm results of autogenous LEB for limb salvage.

METHODS

The PREVENT III trial database includes 1404 North American patients with critical limb ischemia (CLI) who underwent LEB using excised autogenous vein. The study protocol excluded claudicants and in situ reconstructions. Technical factors analyzed included vein diameter, conduit type, graft length, vein orientation, location of proximal and distal anastomoses, and performance of completion imaging. Univariate analysis was used to determine the effect of these factors on 30 day and 1-year outcomes. Multivariate Cox regression models evaluated the influence of these factors while adjusting for age, sex, race, tobacco, diabetes, dialysis-dependency, previous index limb bypass, and study drug (edifoligide) administration. The primary outcomes were primary patency (PP), primary assisted patency (PAP), and secondary patency (SP) assessed by Kaplan-Meier method.

RESULTS

Univariate analysis revealed that vein diameter <3.5 mm and composite graft type were significantly associated with early (30 day) graft failure. At 1 year, multivariate analysis revealed that patency rates were negatively associated with diameter <3.5 mm (PP, PAP, SP), non-great saphenous vein (GSV) type (PP, SP), and graft lengths >50 cm (PP only). Limb salvage and survival at 1 year were not significantly impacted by technical variables. Employing a prespecified trial definition of high-risk conduits (diameter <3mm or nonsingle segment GSV; 24% of entire cohort) revealed that use of such conduits was associated with a 2.1-fold increased risk of 30 day graft failure (P < .05), as well as reduced PP, PAP, and SP at 1 year. Use of a high-risk conduit was also associated with an increased index length of stay (mean 9.37 vs 8.71 days, P = .03) and a greater number of reinterventions (mean 0.67 vs 0.42, P < .0001) over the ensuing year.

CONCLUSIONS

In this large, multicenter cohort of patients undergoing LEB for CLI, vein diameter and conduit type were the dominant technical determinants of early and late graft failure. High-risk conduits and longer grafts may benefit from aggressive postoperative graft surveillance.

Creatine in Huntington disease is safe, tolerable, bioavailable in brain and reduces serum 8OH2'dG

In a randomized, double-blind, placebo-controlled study in 64 subjects with Huntington disease (HD), 8 g/day of creatine administered for 16 weeks was well tolerated and safe. Serum and brain creatine concentrations increased in the creatine-treated group and returned to baseline after washout. Serum 8-hydroxy-2'-deoxyguanosine (8OH2'dG) levels, an indicator of oxidative injury to DNA, were markedly elevated in HD and reduced by creatine treatment.