IMPORTANCE: National initiatives have emphasized the use of autogenous arteriovenous fistulas (AVFs) for hemodialysis, but their purported benefits have been questioned. OBJECTIVE: To examine AVF ...usability, longer-term functional patency, and remedial procedures to facilitate maturation, manage complications, or maintain patency in the Hemodialysis Fistula Maturation (HFM) Study. DESIGN, SETTING, AND PARTICIPANTS: The HFM Study was a multicenter (n = 7) prospective National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases cohort study performed to identify factors associated with AVF maturation. A total of 602 participants were enrolled (dialysis, kidney failure: 380; predialysis, chronic kidney disease CKD: 222) with AVF maturation ascertained for 535 (kidney failure, 353; CKD, 182) participants. INTERVENTIONS: All clinical decisions regarding AVF management were deferred to the individual centers, but remedial interventions were discouraged within 6 weeks of creation. MAIN OUTCOMES AND MEASURES: In this case series analysis, the primary outcome was unassisted maturation. Functional patency, freedom from intervention, and participant survival were summarized using Kaplan-Meier analysis. RESULTS: Most participants evaluated (n = 535) were men (372 69.5%) and had diabetes (311 58.1%); mean (SD) age was 54.6 (13.6) years. Almost two-thirds of the AVFs created (342 of 535 64%) were in the upper arm. The AVF maturation rates for the kidney failure vs CKD participants were 29% vs 10% at 3 months, 67% vs 38% at 6 months, and 76% vs 58% at 12 months. Several participants with kidney failure (133 37.7%) and CKD (63 34.6%) underwent interventions to facilitate maturation or manage complications before maturation. The median time from access creation to maturation was 115 days (interquartile range IQR, 86-171 days) but differed by initial indication (CKD, 170 days; IQR, 113-269 days; kidney failure, 105 days; IQR, 81-137 days). The functional patency for the AVFs that matured at 1 year was 87% (95% CI, 83.2%-90.2%) and at 2 years, 75% (95% CI, 69.7%-79.7%), and there was no significant difference for those receiving interventions before maturation. Almost half (188 47.5%) of the AVFs that matured had further intervention to maintain patency or treat complications. CONCLUSIONS AND RELEVANCE: The findings of this study suggest that AVF remains an accepted hemodialysis access option, although both its maturation and continued use require a moderate number of interventions to maintain patency and treat the associated complications.
Background Surgical site infection (SSI) is a major source of morbidity after infrainguinal lower extremity bypass (LEB). This study examines processes of care associated with in-hospital SSI after ...LEB and identifies factors that could potentially be modified to improve outcomes. Methods The Society for Vascular Surgery (SVS) Vascular Quality Initiative (VQI) registry (2003 to 2012) was queried to identify in-hospital SSI after 7908 consecutive LEB procedures performed by 365 surgeons at 91 academic and community hospitals in 45 states. Variables associated with SSI were identified using multivariable logistic regression and hierarchical clustering. Expected and observed SSI rates were calculated for each hospital. Results The overall in-hospital SSI rate after LEB was 4.8%. Univariate analysis showed that obesity, dialysis, tissue loss, preoperative ankle-brachial index <0.35, distal target, vein graft conduit, continuous incision for vein harvest, transfusion >2 units of packed red blood cells, procedure time >220 minutes, and estimated blood loss >100 mL were associated with higher SSI rates, whereas chlorhexidine (compared with iodine) skin preparation was protective. Multivariable analysis showed independent predictors of SSI included ankle-brachial index <0.35 (odds ratio OR, 1.53; 95% confidence interval CI, 1.03-2.30, P < .04), transfusion >2 units (OR, 3.30; 95% CI, 2.17-5.02; P < .001), and procedure time >220 minutes (OR, 2.11; 95% CI, 1.05-4.23; P < .04). Chlorhexidine was protective against SSI (OR, 0.53; 95% CI, 0.35-0.79; P = .002). Stratified analyses based on the presence of tissue loss yielded similar results. Across VQI hospitals, observed SSI rates ranged from 0% to 30%, whereas expected SSI rates adjusted by the four independent predictors ranged from 0% to 7.2%. Conclusions In-hospital SSI after LEB varies substantially across VQI hospitals. Three modifiable processes of care (transfusion rate, procedure time, and type of skin preparation) were identified and may be used by hospitals to reduce SSI rates. This study demonstrates the value of the SVS VQI detailed shared clinical registry to identify improvement opportunities directly pertinent to providers that are not available in typical administrative data sets.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hydrogen-bearing species in the bone mineral environment were investigated using solid-state NMR spectroscopy of powdered bone, deproteinated bone, and B-type carbonated apatite. Using magic-angle ...spinning and cross-polarization techniques three types of structurally-bound water were observed in these materials. Two of these water types occupy vacancies within the apatitic mineral crystal in synthetic carbonated apatite and deproteinated bone and serve to stabilize these defect-containing crystals. The third water was observed at the mineral surface in unmodified bone but not in deproteinated bone, suggesting a role for this water in mediating mineral-organic matrix interactions. Direct evidence of monohydrogen phosphate in a 1H NMR spectrum of unmodified bone is presented for the first time. We obtained clear evidence for the presence of hydroxide ion in deproteinated bone by 1H MAS NMR. A 1H-31P heteronuclear correlation experiment provided unambiguous evidence for hydroxide ion in unmodified bone as well. Hydroxide ion in both unmodified and deproteinated bone mineral was found to participate in hydrogen bonding with neighboring water molecules and ions. In unmodified bone mineral hydroxide ion was found, through a 1H-31P heteronuclear correlation experiment, to be confined to a small portion of the mineral crystal, probably the internal portion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract Objective Carotid endarterectomy (CEA) has been shown to be an effective treatment for patients with asymptomatic carotid artery stenosis when perioperative stroke rates are low and patients ...survive long enough to benefit from the intervention. Our objective was to develop and to validate a simple risk prediction model for 30-day stroke and 1-year mortality to guide optimal selection of patients for CEA. Methods Asymptomatic patients undergoing first-time elective CEA within the Vascular Quality Initiative (VQI) from 2010 to 2015 were selected. Outcome measures included any 30-day postoperative stroke and 1-year mortality. Patient demographics, comorbidities, carotid artery disease burden, and provider characteristics were evaluated to select a parsimonious clinical model for risk prediction using multivariable logistic regression. Internal validation was performed for stroke and split sample validation was done for 1-year survival to ensure generalizability. Results We identified 31,939 patients for inclusion in the stroke analysis (2010-2015) and 24,086 patients for the mortality analysis (2010-2014). Both the 30-day stroke rate (0.9%) and 1-year mortality rate (3.4%) varied substantially across 265 VQI centers (range, 0%-8.3% and 0%-20%, respectively). Eleven significant factors were selected for the 30-day stroke risk prediction model (area under the receiver operating characteristic curve AUC, 0.67). Internal validation demonstrated good discrimination (bias corrected AUC = 0.652; calibration intercept and slope of 0.03 and 1.01, respectively). Similarly, 10 significant factors were selected for the 1-year mortality risk prediction model (AUC, 0.764). External validation demonstrated excellent discrimination and calibration (AUC, 0.764; 95% confidence interval, 0.72-0.80). Conclusions Stroke and 1-year mortality rates after CEA for asymptomatic stenosis vary across VQI centers. We have developed a preoperative risk model that can be used to accurately estimate risk of perioperative stroke and 1-year mortality and to assist providers in selecting patients with asymptomatic stenosis who are most likely to benefit from CEA.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
IMPORTANCE: Ensuring that patients undergo surveillance imaging after surgery is a key quality metric after many vascular procedures. It is unclear whether hospital participation in a national ...quality improvement registry such as the Vascular Quality Initiative (VQI) achieves this goal. OBJECTIVE: To determine if hospital participation in the VQI registry is associated with increased rates of surveillance imaging after vascular procedures. DESIGN, SETTING, AND PARTICIPANTS: A quasi-experimental study used Medicare claims to study 2174 US hospitals in which 1 530 102 patients had undergone an endovascular abdominal aortic aneurysm repair (EVAR), 1 403 067 patients had undergone a lower extremity bypass (LEB) or peripheral vascular intervention (PVI), and 294 942 patients had undergone carotid endarterectomy (CEA) and carotid artery stenting (CAS) procedures between January 1, 2007, and December 31, 2012. For each hospital, VQI participation was assessed, and a difference-in-differences analysis was used to measure the change in follow-up surveillance for VQI hospitals compared with control (non-VQI) hospitals selected after propensity score matching. The data were analyzed between January and August of 2016. MAIN OUTCOMES AND MEASURES: The proportion of patients who had imaging-based follow-up (computed tomography, duplex ultrasonography, or ankle-brachial index) within 1 year after their vascular procedure. RESULTS: A total of 1 830 928 patients (947 139 women and 883 789 men; mean SD age, 75.8 7.1 years) were identified across 2174 hospitals. Of 3 228 111 total vascular procedures, 1 403 067 patients (43.5%) underwent LEB or PVI, 1 530 102 patients (47.4%) underwent EVAR, and 294 942 patients (9.1%) underwent CEA or CAS. During the 6-year period, follow-up imaging rates varied between 50% and 53% after EVAR, between 52% and 58% after LEB or PVI, and between 74% and 78% after CEA or CAS. A total of 68 VQI participating hospitals were propensity-matched to 68 hospitals, and 279 446 patients were studied across these 136 hospitals. In difference-in-differences analyses, there was no significant improvement in follow-up imaging after joining VQI during year 1 (relative risk, 0.99; 95% CI, 0.97-1.01), year 2 (relative risk, 0.98; 95% CI, 0.95-1.01), or year 3 (relative risk, 0.99; 95% CI, 0.96-1.03). This association was consistent for patients undergoing EVAR, LEB or PVI, and CEA or CAS procedures. CONCLUSIONS AND RELEVANCE: Hospital participation in the VQI registry by itself does not increase rates of surveillance imaging after vascular procedures, suggesting that other strategies are needed to achieve this quality metric.
NMR was used to study the nanostructure of bone tissue. Distance measurements show that the first water layer at the surface of the mineral in cortical bone is structured. This water may serve to ...couple the mineral to the organic matrix and may play a role in deformation.
Introduction: The unique mechanical characteristics of bone tissue have not yet been satisfactorily connected to the exact molecular architecture of this complex composite material. Recently developed solid‐state nuclear magnetic resonance (NMR) techniques are applied here to the mineral component to provide new structural distance constraints at the subnanometer scale.
Materials and Methods: NMR dipolar couplings between structural protons (OH− and H2O) and phosphorus (PO4) or carbon (CO3) were measured using the 2D Lee‐Goldburg Cross‐Polarization under Magic‐Angle Spinning (2D LG‐CPMAS) pulse sequence, which simultaneously suppresses the much stronger proton‐proton dipolar interactions. The NMR dipolar couplings measured provide accurate distances between atoms, e.g., OH and PO4 in apatites. Excised and powdered femoral cortical bone was used for these experiments. Synthetic carbonate (∼2‐4 wt%)‐substituted hydroxyapatite was also studied for structural comparison.
Results: In synthetic apatite, the hydroxide ions are strongly hydrogen bonded to adjacent carbonate or phosphate ions, with hydrogen bond (O‐H) distances of ∼1.96 Å observed. The bone tissue sample, in contrast, shows little evidence of ordered hydroxide. Instead, a very ordered (structural) layer of water molecules is identified, which hydrates the small bioapatite crystallites through very close arrangements. Water protons are ∼2.3‐2.55 Å from surface phosphorus atoms.
Conclusions: In synthetic carbonated apatite, strong hydrogen bonds were observed between the hydroxide ions and structural phosphate and carbonate units in the apatite crystal lattice. These hydrogen bonding interactions may contribute to the long‐range stability of this mineral structure. The biological apatite in cortical bone tissue shows evidence of hydrogen bonding with an ordered surface water layer at the faces of the mineral particles. This structural water layer has been inferred, but direct spectroscopic evidence of this interstitial water is given here. An ordered structural water layer sandwiched between the mineral and the organic collagen fibers may affect the biomechanical properties of this complex composite material.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract Few data prospectively address the role of coping in the development of PTSD. In the present study, 308 undergraduates were assessed for coping prior to the 9/11 WTC attack and for PTSD ...symptomatology at one and three-months post-9/11. Multiple regression analyses indicated that emotion-focused coping was predictive of increased symptomatology at Month 1 and Month 3, whereas problem-focused and avoidance-focused coping were not. Specifically, analyses predicting PTSD symptom factors (Intrusions, Avoidance, Dysphoria, and Hyperarousal) indicated that greater emotion-focused coping predicted increased Dysphoria symptoms at both time points and, among females, increased levels of Hyperarousal symptoms at Month 1. The role of coping style in the development of PTSD symptomatology and its clinical implications are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Background
End‐stage renal disease is accompanied by functional and structural vascular abnormalities. The objective of this study was to characterize vascular function in a large cohort of patients ...with end‐stage renal disease, using noninvasive physiological measurements, and to correlate function with demographic and clinical factors.
Methods and Results
We analyzed cross‐sectional baseline data from the Hemodialysis Fistula Maturation Study, a multicenter prospective observational cohort study of 602 patients with end‐stage renal disease from 7 centers. Brachial artery flow‐ and nitroglycerin‐mediated dilation, carotid‐femoral and ‐radial pulse wave velocity, and venous occlusion plethysmography were performed prior to arteriovenous fistula creation. Relationships of these vascular function measures with demographic, clinical, and laboratory factors were evaluated using linear mixed‐effects models. Arterial function, as assessed by flow‐ and nitroglycerin‐mediated dilation and carotid‐femoral pulse wave velocity, worsened with increasing age and diabetes mellitus. Venous capacitance decreased with diabetes mellitus but not with age. Flow‐mediated dilation was higher among patients undergoing maintenance dialysis than for those at predialysis, and a U‐shaped relationship between serum phosphorus concentration and flow‐mediated dilation was evident. Partial correlations among different measures of vascular function, adjusting for demographic factors, diabetes mellitus, and clinical center, were modest or essentially nonexistent.
Conclusions
Multiple demographic and clinical factors were associated with the functions of vessels of different sizes and types in this large cohort of patients with end‐stage renal disease. Low correlations between the different measures, controlling for demographic factors, diabetes mellitus, and center, indicated that these different types of vascular function otherwise vary heterogeneously across patients.
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