The association of body mass index with risk of long-term revision and 90-day mortality following primary total hip replacement:Findings from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

BACKGROUND: The influence of obesity on outcomes following total hip replacement is unclear. Restriction of total hip replacement on the basis of body mass index (BMI) has been suggested. The purpose of this study was to assess the influence of BMI on the risk of revision and 90-day mortality. METHODS: This was a population-based, longitudinal cohort study of the National Joint Registry (NJR) for England, Wales, Northern Ireland and the Isle of Man. Using data recorded from April 2003 to December 2015, linked to Office for National Statistics data, we ascertained revision and 90-day mortality rates following primary total hip replacement by BMI category. The probability of revision was estimated using Kaplan-Meier methods. Associations of BMI with revision and mortality were explored using adjusted Cox proportional hazards regression models. RESULTS: We investigated revision and 90-day mortality among 415,598 and 413,741 primary total hip replacements, respectively. Each data set accounts for approximately 52% of the total number of recorded operations in the NJR. Thirty-eight percent of the patients were classified as obese. At 10 years, class-III obese patients had the highest cumulative probability of revision (6.7% [95% confidence interval (CI), 5.5% to 8.2%]), twice that of the underweight group (3.3% [95% CI, 2.2% to 4.9%]). When the analysis was adjusted for age, sex, American Society of Anesthesiologists [ASA] grade, year of operation, indication, and fixation type, compared with patients with normal BMI, significantly elevated hazard ratios (HRs) for revision were observed for patients in the BMI categories of class-I obese (≥30 to <35 kg/m) (HR, 1.14 [95% CI, 1.07 to 1.22]), class-II obese (≥35 to <40 kg/m) (HR, 1.30 [95% CI, 1.19 to 1.40]), and class-III obese (≥40 to ≤60 kg/m) (HR, 1.43 [95% CI, 1.27 to 1.61]) (p < 0.0005 for all). Underweight patients had a substantially higher cumulative probability of 90-day mortality (1.17%; 95% CI, 0.86% to 1.58%) compared with patients with normal BMI (0.43%; 95% CI, 0.39% to 0.48%). The risk of 90-day mortality was significantly higher for the underweight group (HR, 2.09 [95% CI, 1.51 to 2.89]; p < 0.0005) and significantly lower for patients who were categorized as overweight (HR, 0.70; 95% CI, 0.61 to 0.81; p < 0.0005), class-I obese (HR, 0.69 [95% CI, 0.59 to 0.81]; p < 0.0005), and class-II obese (HR, 0.79 [95% CI, 0.63 to 0.98]; p = 0.049) compared with patients with normal BMI. CONCLUSIONS: Although long-term revision rates following total hip replacement were higher among obese patients, we believe that the rates remained acceptable by contemporary standards and were balanced by a lower risk of 90-day mortality. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence

Denitrification bioreactor trial in the Russell River catchment of the Wet Tropics: final report

Dissolved inorganic nitrogen (DIN) in runoff from agricultural land is considered to have a significant detrimental impact on the Great Barrier Reef (GBR). Losses of DIN to runoff can be reduced by good agricultural practices, but they cannot be eliminated entirely in the Wet Tropics due to the need for adequate nitrogen supply to crops, the high solubility of DIN, particularly nitrate, and high rainfall. Thus, it is inevitable that DIN concentrations are higher in runoff from agricultural land than from forested areas. Some of this DIN is removed from the water as it moves through aquifers, creeks, rivers, and wetlands on its way to the sea, through the process of microbial denitrification. Denitrification involves the conversion of nitrate and nitrite (NOx-N) to dinitrogen (N2) gas, which is lost to the atmosphere. Denitrification requires NOx-N, organic matter, and low oxygen concentration. Wetlands provide these conditions, so DIN concentrations decline in water moving through them. Similarly, denitrifying bioreactors are designed to treat water by passing it through a porous organic material, typically woodchips. The woodchips provide organic matter for the microorganisms, which in turn lower the oxygen concentration, providing ideal conditions for denitrification. Denitrifying bioreactors are now widely used to remove the NOx-N component of DIN from agricultural runoff water elsewhere, but they have not yet been evaluated in the Wet Tropics. The Wet Tropics pose a challenge for efficacy due to the large volumes of water moving through the landscape. The objective of this project was “to establish the effectiveness of denitrifying bioreactors as a remediation technology for excess DIN in agricultural runoff within the Babinda Swamp Drainage Area (BSDA) of the Russell catchment”. The Russell River exports a disproportionate amount of DIN to the GBR lagoon because of the high rainfall and high proportion of agriculture, mostly sugarcane, in its catchment

Risk-adjusted CUSUM control charts for shared frailty survival models with application to hip replacement outcomes: a study using the NJR dataset

Background:  Continuous monitoring of surgical outcomes after joint replacement is needed to detect which brands’ components have a higher than expected failure rate and are therefore no longer recommended to be used in surgical practice. We developed a monitoring method based on cumulative sum (CUSUM) chart specifically for this application.  Methods:  Our method entails the use of the competing risks model with the Weibull and the Gompertz hazard functions adjusted for observed covariates to approximate the baseline time-to-revision and time-to-death distributions, respectively. The correlated shared frailty terms for competing risks, corresponding to the operating unit, are also included in the model. A bootstrap-based boundary adjustment is then required for risk-adjusted CUSUM charts to guarantee a given probability of the false alarm rates. We propose a method to evaluate the CUSUM scores and the adjusted boundary for a survival model with the shared frailty terms. We also introduce a unit performance quality score based on the posterior frailty distribution. This method is illustrated using the 2003-2012 hip replacement data from the UK National Joint Registry (NJR). Results:  We found that the best model included the shared frailty for revision but not for death. This means that the competing risks of revision and death are independent in NJR data. Our method was superior to the standard NJR methodology. For one of the two monitored components, it produced alarms four years before the increased failure rate came to the attention of the UK regulatory authorities. The hazard ratios of revision across the units varied from 0.38 to 2.28. Conclusions:  An earlier detection of failure signal by our method in comparison to the standard method used by the NJR may be explained by proper risk-adjustment and the ability to accommodate time-dependent hazards. The continuous monitoring of hip replacement outcomes should include risk adjustment at both the individual and unit level

Clinical and biomechanical factors associated with falls and rheumatoid arthritis: Baseline cohort with longitudinal nested case-control study

OBJECTIVE: To identify the clinical and biomechanical characteristics associated with falls in people with RA. METHODS: A total of 436 people ≥60 years of age with RA completed a 1 year prospective survey of falls in the UK. At baseline, questionnaires recorded data including personal and medical history, pain and fatigue scores, health-related quality of life (HRQoL), physical activity and medication history. The occurrence of falls wasmonitored prospectively over 12 months by monthly self-reporting. A nested sample of 30 fallers (defined as the report of one or more falls in 12 months) and 30 non-fallers was evaluated to assess joint range of motion (ROM), muscle strength and gait parameters. Multivariate regression analyses were undertaken to determine variables associated with falling. RESULTS: Compared with non-fallers (n = 236), fallers (n = 200) were older (P = 0.05), less likely to be married (P = 0.03), had higher pain scores (P < 0.01), experienced more frequent dizziness (P < 0.01), were frequently taking psychotropic medications (P = 0.02) and reported lower HRQoL (P = 0.02). Among those who underwent gait laboratory assessments, compared with non-fallers, fallers showed a greater anteroposterior (AP; P = 0.03) and medial-lateral (ML) sway range (P = 0.02) and reduced isokinetic peak torque and isometric strength at 60° knee flexion (P = 0.03). Fallers also showed shorter stride length (P = 0.04), shorter double support time (P = 0.04) and reduced percentage time in swing phase (P = 0.02) and in knee range of motion through the gait cycle (P < 0.01). CONCLUSION: People with RA have distinct clinical and biomechanical characteristics that place them at increased risk of falling. Assessment for these factors may be important to offer more targeted rehabilitation interventions

The prevalence of giant cell arteritis and polymyalgia rheumatica in a UK primary care population

Background: To update community-based prevalence values for Polymyalgia Rheumatic (PMR) and Giant Cell Arteritis (GCA) using case record review supplemented by population survey and subsequent clinical review. Methods: Clinical data were obtained from case records of a large primary care practice in Norfolk, UK and reviewed for diagnoses of GCA and PMR. In addition postal survey was carried out to capture potentially undiagnosed cases within the practice population. Those screening positive for potential diagnoses of GCA and PMR were invited for clinical review. A cumulative prevalence estimate was subsequently calculated on those diagnosed within the GP practice and subsequently on those fulfilling the various published classification criteria sets. The date of the database lock and mail merge was March 2013. Results: Through detailed systematic review of 5,159 GP case records, 21 patients had a recorded diagnosis of GCA and 117 had PMR . No new cases were identified among 2,227 completed questionnaires returned from the population survey of a sample of 4,728. The resulting cumulative prevalence estimate in those aged ≥55 years meeting the ACR classification criteria set for GCA was 0.25% (95% CI 0.11% to 0.39%) and for five published criteria sets for PMR ranged from 0.91% to 1.53% (95% CI ranges 0.65%, 1.87%). The prevalence of both conditions was higher in women than in men and in older age groups. Conclusion: This study provides the first UK prevalence estimate of GCA and PMR in over 30 years and is the first to apply classification criteria sets

Performance of the LHCb vertex locator

The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 μm is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means that the inner regions of the n+-on-n sensors have undergone space-charge sign inversion due to radiation damage. The VELO performance parameters that drive the experiment's physics sensitivity are also given. The track finding efficiency of the VELO is typically above 98% and the modules have been aligned to a precision of 1 μm for translations in the plane transverse to the beam. A primary vertex resolution of 13 μm in the transverse plane and 71 μm along the beam axis is achieved for vertices with 25 tracks. An impact parameter resolution of less than 35 μm is achieved for particles with transverse momentum greater than 1 GeV/c

Precision luminosity measurements at LHCb

Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy √s. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for √s = 2.76, 7 and 8 TeV (proton-proton collisions) and for √sNN = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at √s = 8 TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determines the luminosity with a precision of 1.16%. This represents the most precise luminosity measurement achieved so far at a bunched-beam hadron collider

Enabling New ALMA Science with Improved Support for Time-Domain Observations

While the Atacama Large Millimeter/submillimeter Array (ALMA) is a uniquely powerful telescope, its impact in certain fields of astrophysics has been limited by observatory policies rather than the telescope's innate technical capabilities. In particular, several observatory policies present challenges for observations of variable, mobile, and/or transient sources --- collectively referred to here as "time-domain" observations. In this whitepaper we identify some of these policies, describe the scientific applications they impair, and suggest changes that would increase ALMA's science impact in Cycle 6 and beyond. Parties interested in time-domain science with ALMA are encouraged to join the ALMA Time-domain Special Interest Group (ATSIG) by signing up for the ATSIG mailing list at https://groups.google.com/group/alma-td-sig