Peter J. Rossi

Account-Level Modeling for Trade Promotion: An Application of a Constrained Parameter Hierarchical Model

Abstract We consider the problem of utilizing data at the retail/market level on sales and marketing mix variables to help manufacturers optimize the allocation of trade promotional budgets across areas. Major consumer packaged goods manufacturers budget at least one-half of their total marketing expenses to trade promotions. Trade promotional deals are designed to encourage retailers to promote products by temporarily reducing the price, putting them in in-store displays, or advertising in local media. A profit-based trade promotional allocation system will require estimates of the responsiveness of sales at each retailer to a given promotion. A major barrier to the use of retailer data is the proliferation of incorrectly signed coefficients in standard least squares analyses. Even more sophisticated adaptive shrinkage methods will not remove the problem of improper signs. We propose a hierarchical model to modeling retailer response that uses a first-stage prior with inequality constraints on the regres...

Reducing the Risk of Surgical Site Infections: Did We Really Think SCIP Was Going to Lead Us to the Promised Land?

BACKGROUNDnSurgical site infections (SSIs) are associated with substantial patient morbidity and death. It is estimated that 750,000-1 million SSIs occur in the U.S. each year, utilizing 3.7 million extra hospital days and costing more than

Evidence for a Standardized Preadmission Showering Regimen to Achieve Maximal Antiseptic Skin Surface Concentrations of Chlorhexidine Gluconate, 4%, in Surgical Patients

1.6 billion in excess hospital charges.nnnMETHODnReview of pertinent English-language literature.nnnRESULTSnThe Surgical Care Improvement Project (SCIP) was embraced as a one-size-fits-all strategy to reduce postoperative infectious morbidity 25% by 2010. Unfortunately, the evidence suggests that SCIP by itself has had little efficacy in reducing the overall risk of SSI. Whereas the SCIP initiative represents a first national effort to focus on reducing postoperative infectious morbidity and deaths, it fails to consider salient risk factors such as body mass index and selected surgical practices, including tourniquet application prior to incision.nnnCONCLUSIONnRather than focus on a single risk-reduction strategy, future efforts to improve surgical outcomes should embrace a SCIP-plus multi-faceted, tiered interventional strategy that includes pre-admission antiseptic showering, state-of-the-art skin antisepsis, innovative antimicrobial technology, active staphylococcal surveillance, and pharmacologic-physiologic considerations unique to selective patient populations.

Surgical Site Infections after Lower Extremity Revascularization Procedures Involving Groin Incisions

IMPORTANCEnTo reduce the amount of skin surface bacteria for patients undergoing elective surgery, selective health care facilities have instituted a preadmission antiseptic skin cleansing protocol using chlorhexidine gluconate. A Cochrane Collaborative review suggests that existing data do not justify preoperative skin cleansing as a strategy to reduce surgical site infection.nnnOBJECTIVESnTo develop and evaluate the efficacy of a standardized preadmission showering protocol that optimizes skin surface concentrations of chlorhexidine gluconate and to compare the findings with the design and methods of published studies on preoperative skin preparation.nnnDESIGN, SETTING, AND PARTICIPANTSnA randomized prospective analysis in 120 healthy volunteers was conducted at an academic tertiary care medical center from June 1, 2014, to September, 30, 2014. Data analysis was performed from October 13, 2014, to October 27, 2014. A standardized process of dose, duration, and timing was used to maximize antiseptic skin surface concentrations of chlorhexidine gluconate applied during preoperative showering. The volunteers were randomized to 2 chlorhexidine gluconate, 4%, showering groups (2 vs 3 showers), containing 60 participants each, and 3 subgroups (no pause, 1-minute pause, or 2-minute pause before rinsing), containing 20 participants each. Volunteers used 118 mL of chlorhexidine gluconate, 4%, for each shower. Skin surface concentrations of chlorhexidine gluconate were analyzed using colorimetric assay at 5 separate anatomic sites. Individual groups were analyzed using paired t test and analysis of variance.nnnINTERVENTIONnPreadmission showers using chlorhexidine gluconate, 4%.nnnMAIN OUTCOMES AND MEASURESnThe primary outcome was to develop a standardized approach for administering the preadmission shower with chlorhexidine gluconate, 4%, resulting in maximal, persistent skin antisepsis by delineating a precise dose (volume) of chlorhexidine gluconate, 4%; duration (number of showers); and timing (pause) before rinsing.nnnRESULTSnThe mean (SD) composite chlorhexidine gluconate concentrations were significantly higher (Pu2009<u2009.001) in the 1- and 2-minute pause groups compared with the no-pause group in participants taking 2 (978.8 [234.6], 1042.2 [219.9], and 265.6 [113.3] µg/mL, respectively) or 3 (1067.2 [205.6], 1017.9 [227.8], and 387.1 [217.5] µg/mL, respectively) showers. There was no significant difference in concentrations between 2 and 3 showers or between the 1- and 2-minute pauses.nnnCONCLUSIONS AND RELEVANCEnA standardized preadmission shower regimen that includes 118 mL of aqueous chlorhexidine gluconate, 4%, per shower; a minimum of 2 sequential showers; and a 1-minute pause before rinsing results in maximal skin surface (16.5 µg/cm2) concentrations of chlorhexidine gluconate that are sufficient to inhibit or kill gram-positive or gram-negative surgical wound pathogens. This showering regimen corrects deficiencies present in current nonstandardized preadmission shower protocols for patients undergoing elective surgery.

Microbial pathogenesis of bacterial biofilms: a causative factor of vascular surgical site infection.

BACKGROUNDnWe sought to evaluate the incidence, epidemiology, and factors associated with surgical site infections (SSIs) after lower extremity revascularization procedures involving groin incisions and determine outcomes based on SSI status.nnnMETHODSnThis is a single-institution, retrospective cohort study of 106 patients who underwent lower extremity revascularization procedures involving femoral artery exposure through a groin incision at a tertiary referral hospital. The primary outcome was occurrence of SSI at the groin wound. The duration of hospital stay, reoperation within 30xa0days, discharge disposition, and 30-day mortality were also evaluated. Independent variables included patient demographics and operative variables (i.e., procedure type, transfusion requirements, preoperative antibiotics, intraoperative vasopressors, and operative duration). Statistical analysis included chi-squared tests, t-tests, and multivariable regression analysis.nnnRESULTSnOf the 106 patients who underwent a lower extremity revascularization procedure with a groin incision for femoral artery exposure, 62% were male, and the mean age was 62xa0years. Comorbidities included hypertension (93%), dyslipidemia (65%), statin use (63%), active smoker (50%), diabetes (24%), and chronic obstructive pulmonary disease (23%). All patients received preoperative antibiotics, 50% required intraoperative pressors, 21% received a blood transfusion, and the mean operative time was 296xa0min. The overall duration of stay was 10.7xa0days, the 30-day reoperation rate was 18%, and the 30-day mortality rate was 12%. Overall, 22% developed a seroma or hematoma, and 31% developed a SSI. Patients who developed an SSI compared with those who did not were more likely to have a postoperative seroma or hematoma (55% vs 5%) and to receive a blood transfusion (33% vs 15%), but less likely to be treated with a statin (47% vs 69%) or carry a diagnosis of dyslipidemia (50% vs 72%), respectively, all Pxa0<xa00.05. Patients with an SSI had a longer duration of stay (14.5 vs 8.7xa0days) and a higher reoperative rate (49% vs 4%), but had a lower 30-day mortality (0% vs 18%) than those who did not develop an SSI (all Pxa0<xa00.05). On multivariable regression analysis adjusting for differences in patient and operative variables, the occurrence of a wound seroma or hematoma remained an independent predictor for SSI (odd ratio: 27.6; 95% confidence interval: 5.4-139.6).nnnCONCLUSIONSnThe incidence of postoperative surgical site complications after lower extremity revascularization procedures involving a groin incision was 31% and was significantly associated with blood transfusion, postoperative seroma or hematoma, dyslipidemia, and statin usage. After adjusting for differences in patient and operative variables, postoperative seroma or hematoma was an independent predictor of SSI. Patients with a SSI have a longer duration of hospitalization and higher reoperative rate. Additional prospective cohort studies are warranted to delineate ways to decrease the rate of SSI.

Microbiology of Explanted Suture Segments from Infected and Noninfected Surgical Patients

Vascular surgical site infection (SSI) is caused by pathogenic bacterial strains whose preferred mode of growth is within a surface biofilm. Bacterial biofilm formation can develop within hours to days in a wound and produces a recalcitrant infectious process especially in the presence of a prosthetic graft. The initial steps of biofilm formation are bacterial adhesion to biologic or inert surgical site structures followed by organism production of exopolysaccaride matrix which encases developing bacteria colonies to produce a protective microenvironment. As the biofilm matures, a dynamic process of organism cell-to-cell signaling occurs with varying growth modes of sessile bacteria within the biofilm and the release of planktonic bacteria with the potential to spread and expand the biofilm-mediated infection. The prevalence of staphyloccocal strains causing vascular SSI is best understood when viewed as a biofilm-mediated infection with virulence factors related to specific cell surface adhesion proteins and bacteria-derived matrix production. Nonhealing surgical sites following lower limb revascularization, the late appearance of prosthetic graft infection caused by Staphylococcus epidermidis, and the development of groin site tracts after aortofemoral bypass grafting are clinical examples of a biofilm-mediated SSI. A mature biofilm within a wound or coating a prosthetic device exhibits resistance to host defenses and selected antibiotics, impairs wound healing, and is a perpetual irritant to that host by inciting a chronic inflammatory process. By understanding the microbial pathogenesis of biofilm formation, strategies to treat and prevent biofilm-mediated infection can be developed and utilized to reduce vascular SSIs.

The effect of Surgical Care Improvement Project measures on national trends on surgical site infections in open vascular procedures.

ABSTRACT Sutures under selective host/environmental factors can potentiate postoperative surgical site infection (SSI). The present investigation characterized microbial recovery and biofilm formation from explanted absorbable (AB) and nonabsorbable (NAB) sutures from infected and noninfected sites. AB and NAB sutures were harvested from noninfected (70.9%) and infected (29.1%) sites in 158 patients. At explantation, devices were sonicated and processed for qualitative/quantitative bacteriology; selective sutures were processed for scanning electron microscopy (SEM). Bacteria were recovered from 85 (53.8%) explanted sites; 39 sites were noninfected, and 46 were infected. Suture recovery ranged from 11.1 to 574.6 days postinsertion. A significant difference in mean microbial recovery between noninfected (1.2 isolates) and infected (2.7 isolates) devices (P < 0.05) was noted. Staphylococcus epidermidis, Staphylococcus aureus, coagulase-negative staphylococci (CNS), Peptostreptococcus spp., Bacteroides fragilis, Escherichia coli, Enterococcus spp., Pseudomonas aeruginosa, and Serratia spp. were recovered from infected devices, while commensal skin flora was recovered from noninfected devices. No significant difference in quantitative microbial recovery between infected monofilament and multifilament sutures was noted. Biofilm was present in 100% and 66.6% of infected and noninfected devices, respectively (P < 0.042). We conclude that both monofilament and braided sutures provide a hospitable surface for microbial adherence: (i) a significant difference in microbial recovery from infected and noninfected sutures was noted, (ii) infected sutures harbored a mixed flora, including multidrug-resistant health care-associated pathogens, and (iii) a significant difference in the presence or absence of a biofilm in infected versus noninfected explanted devices was noted. Further studies to document the benefit of focused risk reduction strategies to minimize suture contamination and biofilm formation postimplantation are warranted.

Empowering the Surgical Patient: A Randomized, Prospective Analysis of an Innovative Strategy for Improving Patient Compliance with Preadmission Showering Protocol

OBJECTIVEnThe Surgical Care Improvement Project (SCIP) is a national initiative to reduce surgical complications, including postoperative surgical site infection (SSI), through protocol-driven antibiotic usage. This study aimed to determine the effect SCIP guidelines have had on in-hospital SSIs after open vascular procedures.nnnMETHODSnThe Nationwide Inpatient Sample (NIS) was retrospectively analyzed using International Classification of Diseases, Ninth Revision, diagnosis codes to capture SSIs in hospital patients who underwent elective carotid endarterectomy, elective open repair of an abdominal aortic aneurysm (AAA), and peripheral bypass. The pre-SCIP era was defined as 2000 to 2005 and post-SCIP was defined as 2007 to 2010. The year 2006 was excluded because this was the transition year in which the SCIP guidelines were implemented. Analysis of variance and χ(2) testing were used for statistical analysis.nnnRESULTSnThe rate of SSI in the pre-SCIP era was 2.2% compared with 2.3% for carotid endarterectomy (P = .06). For peripheral bypass, both in the pre- and post-SCIP era, infection rates were 0.1% (P = .22). For open, elective AAA, the rate of infection in the post-SCIP era increased significantly to 1.4% from 1.0% in the pre-SCIP era (P < .001). Demographics and in-hospital mortality did not differ significantly between the groups.nnnCONCLUSIONSnImplementation of SCIP guidelines has made no significant effect on the incidence of in-hospital SSIs in open vascular operations; rather, an increase in SSI rates in open AAA repairs was observed. Patient-centered, bundled approaches to care, rather than current SCIP practices, may further decrease SSI rates in vascular patients undergoing open procedures.

Management of Carotid Stenosis in Women

BACKGROUNDnSurgical site infections (SSIs) are responsible for significant morbidity, mortality, and excess use of health care resources. The preadmission antiseptic shower is accepted as an effective strategy for reducing the risk for SSIs. The study analyzes the benefit of an innovative electronic patient alert system (EAS) for enhancing compliance with a preadmission showering protocol with 4% chlorhexidine gluconate (CHG).nnnSTUDY DESIGNnAfter providing informed consent, 80 volunteers were randomized to 4 CHG showering groups. Groups A1 and A2 showered twice. Group A1 was prompted to shower via EAS. Groups B1 and B2 showered 3 times. Group B1 was prompted via EAS. Subjects in groups A2 and B2 were not prompted (non-EAS groups). Skin-surface concentrations of CHG (μg/mL) were analyzed using colorimetric assay at 5 separate anatomic sites. Study personnel were blinded to the randomization code; after final volunteer processing, the code was broken and individual groups were analyzed.nnnRESULTSnMean composite CHG skin-surface concentrations were significantly higher (p < 0.007) in EAS groups A1 (30.9 ± 8.8 μg/mL) and B1 (29.0 ± 8.3 μg/mL) compared with non-EAS groups A2 (10.5 ± 3.9 μg/mL) and B2 (9.5 ± 3.1 μg/mL). Overall, 66% and 67% reductions in CHG skin-surface concentrations were observed in non-EAS groups A2 and B2 compared with EAS study groups. Analysis of returned (unused) CHG (mL) suggests that a wide variation in volume of biocide was used per shower in all groups.nnnCONCLUSIONSnThe findings suggest that EAS was effective in enhancing patient compliance with a preadmission showering protocol, resulting in a significant (p < 0.007) increase in skin-surface concentrations of CHG compared with non-EAS controls. However, variation in amount of unused 4% CHG suggests that rigorous standardization is required to maximize the benefits of this patient-centric interventional strategy.

The extent of lower extremity occlusive disease predicts short- and long-term patency following endovascular infrainguinal arterial intervention

The management of carotid stenosis in women remains a topic of controversy. In this review article, we aimed to define carotid disease burden in women, review outcomes of carotid endarterectomy and carotid artery stenting in women, discuss differences in practice patterns based on sex, and provide guidelines for management of women with carotid stenosis. Symptomatic women with high-grade stenosis derive benefit from carotid endarterectomy, although they have different risk profiles than men and are often not taking appropriate medical therapy. Women with asymptomatic carotid artery stenosis have less stroke risk reduction with CEA than their male counterparts; therefore, they should be screened for other treatable risk factors for stroke, with the institution of lifestyle changes and the appropriate medical therapy. After medical optimization, the decision to proceed with CEA in asymptomatic women must be made by carefully assessing that the benefits of stroke risk reduction outweigh perioperative risks.