Lateral Femoral Condyle Allograft in the Treatment of Elbow Capitellar Avascular Necrosis: A Case Report.

CASE: A 27-year-old woman developed capitellar osteonecrosis after long-term corticosteroid use to treat non-Hodgkin lymphoma. She underwent an osteochondral reconstruction using a lateral femoral condyle (LFC) allograft. This graft was selected because it has a similar radius of curvature to the capitellum. The patient had osseous integration, painless, near full range of motion of her elbow 6 months postoperatively and good shoulder function 1.0 year postoperatively. CONCLUSION: The LFC allograft should be considered a viable option in treating capitellar osteonecrosis.

Hip, knee, and shoulder arthroplasty in patients with a history of solid organ transplant: A review.

Solid organ transplants (SOT) have evolved into life-saving interventions for end-stage diseases affecting vital organs. Advances in transplantation techniques, donor selection, and immunosuppressive therapies have enhanced outcomes, leading to a growing demand for SOT. Patients with a solid organ transplant are living long enough to develop the same pathologies which are indicated for joint replacement surgery in the general population. SOT patients who undergo a total hip, knee, or shoulder arthroplasty do similarly in the context of clinical outcomes and implant survival when compared to the general population. These immunosuppressed patients tend to have higher complication rates in the short-term following surgery. Prudent management of these patients in the short-term may be necessary, but patients can expect to do well otherwise.

Modern Applications of Machine Learning in Shoulder Arthroplasty: A Review.

¼ There is increased integration of machine learning (ML) to aid clinical decision-making in orthopaedic surgery.¼ ML has the ability to predict both clinical outcomes such as range of motion and complications in total shoulder arthroplasty patients.¼ An increased area of focus is the ability for ML to identify implants to aid in revision surgery planning.¼ In this article, we review the current applications of ML in shoulder arthroplasty and discuss future areas where it may enhance orthopaedic practice.

Outcomes of Reverse Total Shoulder Arthroplasty Were Not Adversely Affected by the COVID-19 Pandemic.

Introduction: The objective was to investigate outcomes in reverse total shoulder arthroplasty (RTSA) in patients affected by the COVID-19 pandemic shutdown. We hypothesized that patients undergoing RTSA in early 2020 would have decreased access to physical therapy (PT) and worse postoperative outcomes compared to historical controls. Materials and Methods: Patients who received primary RTSA between 1/1/2020 to 3/17/2020 were included and patients who received primary RTSA between 1/1/2019 to 3/17/2019 were used as a control group. Retrospective chart review was performed, and patient reported outcomes were recorded at an average of 2.69 ± 0.06 years and a minimum of 1 year postoperatively. Patient data were collected and statistically analyzed using the 2-sample t-test and Chi-square test. The Mann Whitney U test and Fisher's Exact test were used when appropriate. Results: 38 patients in 2020 were included in this study and compared to 31 patients in 2019. RTSA performed in 2019 had improvements in forward elevation (FE) (95.7º ± 47.2º to 144.7º ± 17.2º, p<0.001), but not in external rotation (ER) (32.5º ± 20.3º to 41.0º ± 13.3º, p=0.15), or internal rotation (IR) (S1 to L5, p=0.76). RTSA 2020 cases had improvements in FE (111.5º ± 40.3 to 132.8º ± 30.6, p=0.016), but not ER (31.9º ± 18.2 to 35.7º ± 15.9, p=0.36) or IR (S1 to L5, p=0.13). Patients in 2019 (FE: 4 to 5-, p<0.001; ER: 4+ to 5-, p=0.003; IR: 5- to 5, p<0.001) and 2020 (FE: 4 to 5-, p<0.001; ER: 4+ to 5, p<0.001; IR: 5- to 5, p=0.02) both experienced improvements in strength. Patients in 2020 initiated PT later (2019: 39.3 ± 27.3 days, 2020: 57.1 ± 35.5 days, p=0.028) and completed less PT sessions (2019: 20.7 ± 11.1, 2020: 12.9 ± 6.6, p<0.001) than patients in 2019. In the 2020 cohort, 10.5% (4/38) did not complete any PT, 34.2% (13/38) reported a delay in initiating PT, and 47.4% (18/38) reported that their recovery was negatively affected by the COVID-19 pandemic. At final follow-up, patients in 2020 reported a mean SANE score of 73.6 ± 17.5 on their affected shoulder and a mean VAS score of 1.68 ± 1.23. Discussion: Despite a delay in initiating PT and completing less PT overall, patients who received RTSA in 2020 experienced significant improvements in ROM and strength at final follow-up and were comparable to the 2019 patients.

Shoulder arthroplasty following solid organ transplant: A systematic review and meta-analysis.

Introduction: The purpose of this study is to report a systematic review and meta-analysis of solid organ transplant (SOT) patients undergoing shoulder arthroplasty to compare functional and radiographic outcomes, demographics, and complications with non-transplant patients. Methods: Studies were included if they examined patients undergoing shoulder arthroplasty in the setting of prior solid organ transplantation and included post operative range of motion, patient-reported outcomes, complications, or revisions. Studies were excluded if they were national database analyses or lacked clinical data. Pubmed, MEDLine, Scopus, and Web of Science were queried using relevant search terms in July 2022. Data was pooled, weighted, and a paired t-test and chi-square analysis was performed. Results: There were 71 SOT and 159 non-SOT shoulders included in the study. The most common indication for surgery was avascular necrosis (n = 26) in the solid organ transplant group and osteoarthritis (n = 60) in the non-SOT group. Forward elevation, external rotation, ASES, and VAS pain scores improved significantly in both cohorts following surgery. There was no significant difference in age at surgery (p-value = 0.20), postoperative forward elevation (p-value = 0.08), postoperative external rotation (0.84), and postoperative ASES scores (p-value = 0.11) between the two cohorts. VAS pain scores were significantly lower in the SOT cohort (p-value<0.01). The risk of death was significantly higher in the SOT group (p-value<0.01). but the rate of overall complications (p = 0.47), surgical complication (p-value = 0.79), or revision surgery (p-value = 1.00) was not significantly different between the two cohorts. Conclusion: Shoulder arthroplasty is a safe, effective option in patients following solid organ transplant. There is not an increased risk of adverse outcomes, and SOT patients had comparable range of motion and patient-reported outcomes when compared to their non-SOT peers. Level of evidence: III.

Antigiardial Activity of Novel Guanidine Compounds.

From four focused compound libraries based on the known anticoccidial agent robenidine, 44 compounds total were synthesised and screened for antigiardial activity. All active compounds were counter-screened for antibiotic and cytotoxic action. Of the analogues examined, 21 displayed IC50 <5 µM, seven with IC50 <1.0 µM. Most active were 2,2'-bis{[4-(trifluoromethoxy)phenyl]methylene}carbonimidic dihydrazide hydrochloride (30), 2,2'-bis{[4-(trifluoromethylsulfanyl)phenyl]methylene}carbonimidic dihydrazide hydrochloride (32), and 2,2'-bis[(2-bromo-4,5-dimethoxyphenyl)methylene]carbonimidic dihydrazide hydrochloride (41) with IC50 =0.2 µM. The maximal observed activity was a 5 h IC50 value of 0.2 µM for 41. The clinically used metronidazole was inactive at this timepoint at a concentration of 25 µM. Robenidine off-target effects at bacteria and cell line toxicity were removed. Analogue 41 was well tolerated in mice treated orally (100 mg/kg). Following 5 h treatment with 41, no Giardia regrowth was noted after 48 h.

Minimising damage in high resolution scanning transmission electron microscope images of nanoscale structures and processes.

Beam damage caused during acquisition of the highest resolution images is the current limitation in the vast majority of experiments performed in a scanning transmission electron microscope (STEM). While the principles behind the processes of knock-on and radiolysis damage are well-known (as are other contributing effects, such as heat and electric fields), understanding how and especially when beam damage is distributed across the entire sample volume during an experiment has not been examined in detail. Here we use standard models for damage and diffusion to elucidate how beam damage spreads across the sample as a function of the microscope conditions to determine an "optimum" sampling approach that maximises the high-resolution information in any image acquisition. We find that the standard STEM approach of scanning an image sequentially accelerates damage because of increased overlap of diffusion processes. These regions of accelerated damage can be significantly decelerated by increasing the distance between the acquired pixels in the scan, forming a "spotscan" mode of acquisition. The optimum distance between these pixels can be broadly defined by the fundamental properties of each material, allowing experiments to be designed for specific beam sensitive materials. As an added bonus, if we use inpainting to reconstruct the sparse distribution of pixels in the image we can significantly increase the speed of the STEM process, allowing dynamic phenomena, and the onset of damage, to be studied directly.

Evaluating Relationships Between Sleep and Next-Day Physical Activity in Young Women.

BACKGROUND: To evaluate the relationship between sleep and next-day physical activity (PA) under free-living conditions in women. METHODS: Sleep and PA were measured objectively for 7 consecutive days by accelerometry in 330 young adult women (aged 17-25 y). A structural equation model was used to evaluate the relationship between the driving factor of sleep (total sleep or morning wake time) and the amount of nonsleep sedentary (SED) and moderate to vigorous physical activity (MVPA) each day. RESULTS: With sleep duration as the driving factor, the estimates of ßSED and ßMVPA were -0.415 and -0.093, respectively (P ≤ .05). For every hour slept, a 24.9-minute reduction in SED time and a 5.58-minute reduction in MVPA were observed. With wake time as the driving factor, the estimates of ßSED and ßMVPA were -0.636 and -0.149, respectively. For every wake time that was 1 hour later, a 38.2-minute decrease in SED and a 8.9-minute decrease in MVPA (P ≤ .05) were observed. CONCLUSIONS: Women who wake later or who sleep longer tend to get less MVPA throughout the day. Getting up earlier and going to bed earlier may support behaviors that improve PA and lifestyle.

Aminoguanidines: New leads for treatment of Giardia duodenalis infection.

Giardia duodenalis is an ubiquitous parasitic pathogen that causes significant morbidity and mortality worldwide. Failures in drug therapy are commonly due to poor patient compliance as a result of the need for repeated administration, off target drug effects and increasing parasite drug resistance. In this study the in vitro efficacy and selectivity of the aminoguanidine compound robenidine and 2 structural analogues against Giardia were determined. After 5 h exposure to each compound the IC50 was as low as 0.2 µM with corresponding MLCs as low as 2.8 µM. This is in contrast to metronidazole which required 24 h to exhibit inhibitory activity. A modified adherence assay, developed for this study, demonstrated that three of the compounds inhibited in vitro adherence of the parasite. The lead compound exhibited rapid giardicidal activity (<5hr). In addition, microscopy studies demonstrated damage to the plasma membrane of trophozoites. In conclusion, a class of aminoguanidines, represented by robenidine, has shown antigiardial activity warranting further investigation.

Evaluation of robenidine analog NCL195 as a novel broad-spectrum antibacterial agent.

The spread of multidrug resistance among bacterial pathogens poses a serious threat to public health worldwide. Recent approaches towards combating antimicrobial resistance include repurposing old compounds with known safety and development pathways as new antibacterial classes with novel mechanisms of action. Here we show that an analog of the anticoccidial drug robenidine (4,6-bis(2-((E)-4-methylbenzylidene)hydrazinyl)pyrimidin-2-amine; NCL195) displays potent bactericidal activity against Streptococcus pneumoniae and Staphylococcus aureus by disrupting the cell membrane potential. NCL195 was less cytotoxic to mammalian cell lines than the parent compound, showed low metabolic degradation rates by human and mouse liver microsomes, and exhibited high plasma concentration and low plasma clearance rates in mice. NCL195 was bactericidal against Acinetobacter spp and Neisseria meningitidis and also demonstrated potent activity against A. baumannii, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Enterobacter spp. in the presence of sub-inhibitory concentrations of ethylenediaminetetraacetic acid (EDTA) and polymyxin B. These findings demonstrate that NCL195 represents a new chemical lead for further medicinal chemistry and pharmaceutical development to enhance potency, solubility and selectivity against serious bacterial pathogens.

Bridging Zirconia Nodes within a Metal-Organic Framework via Catalytic Ni-Hydroxo Clusters to Form Heterobimetallic Nanowires.

Metal-organic frameworks (MOFs), with their well-ordered pore networks and tunable surface chemistries, offer a versatile platform for preparing well-defined nanostructures wherein functionality such as catalysis can be incorporated. Notably, atomic layer deposition (ALD) in MOFs has recently emerged as a versatile approach to functionalize MOF surfaces with a wide variety of catalytic metal-oxo species. Understanding the structure of newly deposited species and how they are tethered within the MOF is critical to understanding how these components couple to govern the active material properties. By combining local and long-range structure probes, including X-ray absorption spectroscopy, pair distribution function analysis, and difference envelope density analysis, with electron microscopy imaging and computational modeling, we resolve the precise atomic structure of metal-oxo species deposited in the MOF NU-1000 through ALD. These analyses demonstrate that deposition of NiOxHy clusters occurs selectively within the smallest pores of NU-1000, between the zirconia nodes, serving to connect these nodes along the c-direction to yield heterobimetallic metal-oxo nanowires. This bridging motif perturbs the NU-1000 framework structure, drawing the zirconia nodes closer together, and also underlies the sintering resistance of these clusters during the hydrogenation of light olefins.

Robenidine Analogues as Gram-Positive Antibacterial Agents.

Robenidine, 1 (2,2'-bis[(4-chlorophenyl)methylene]carbonimidic dihydrazide), was active against MRSA and VRE with MIC's of 8.1 and 4.7 µM, respectively. SAR revealed tolerance for 4-Cl isosteres with 4-F (8), 3-F (9), 3-CH3 (22), and 4-C(CH3)3 (27) (23.7-71 µM) and with 3-Cl (3), 4-CH3 (21), and 4-CH(CH3)2 (26) (8.1-13.0 µM). Imine carbon alkylation identified a methyl/ethyl binding pocket that also accommodated a CH2OH moiety (75; 2,2'-bis[1-(4-chlorophenyl)-2-hydroxyethylidene]carbonimidic dihydrazide). Analogues 1, 27 (2,2'-bis{[4-(1,1-dimethylethyl)phenyl]methylene}carbonimidic dihydrazide), and 69 (2,2'-bis[1-(4-chlorophenyl)ethylidene]carbonimidic dihydrazide hydrochloride) were active against 24 clinical MRSA and MSSA isolates. No dose-limiting cytotoxicity at ≥2× MIC or hemolysis at ≥8× MIC was observed. Polymyxin B addition engendered Escherichia coli and Pseudomonas aeruginosa Gram-negative activity MIC's of 4.2-21.6 µM. 1 and 75 displayed excellent microsomal stability, intrinsic clearance, and hepatic extraction ratios with T1/2 > 247 min, CLint < 7 µL/min/mg protein, and EH < 0.22 in both human and mouse liposomes for 1 and in human liposomes for 75.

Secular trends and evaluation of complex interventions: the rising tide phenomenon.

Evaluations of service delivery interventions with contemporaneous controls often yield null results, even when the intervention appeared promising in advance. There can be many reasons for null results. In this paper we introduce the concept of a 'rising tide' phenomenon being a possible explanation of null results. We note that evaluations of service delivery interventions often occur when awareness of the problems they intend to address is already heightened, and pressure to tackle them is mounting throughout a health system. An evaluation may therefore take place in a setting where the system as a whole is improving - where there is a pronounced temporal trend or a 'rising tide causing all vessels to rise'. As a consequence, control sites in an intervention study will improve. This reduces the difference between intervention and control sites and predisposes the study to a null result, leading to the conclusion that the intervention has no effect. We discuss how a rising tide may be distinguished from other causes of improvement in both control and intervention groups, and give examples where the rising tide provides a convincing explanation of such a finding. We offer recommendations for interpretation of research findings where improvements in the intervention group are matched by improvements in the control group. Understanding the rising tide phenomenon is important for a more nuanced interpretation of null results arising in the context of system-wide improvement. Recognition that a rising tide may have predisposed to a null result in one health system cautions against generalising the result to another health system where strong secular trends are absent.

Trends in clinical development timeframes for antiviral drugs launched in the UK, 1981-2014: a retrospective observational study.

OBJECTIVES: Recent decades have witnessed the development of highly innovative new antiviral drug therapies. However, there are concerns that rising costs and lengthening development times could have implications for future patient access to innovative new drugs. We sought to establish whether the time taken for the clinical development of new antiviral drugs launched in the UK had increased since the 1980s. DESIGN AND SETTING: Retrospective observational study of all new antiviral drugs licensed for use in the UK. PRIMARY AND SECONDARY OUTCOME MEASURES: Duration of clinical development (from initiation of studies in humans to receipt of Marketing Authorisation), subdivided into clinical trial and regulatory approval periods by the date of Marketing Authorisation Application. RESULTS: 48 new antiviral drugs were licensed for use in the UK between 1981 and 2014 (inclusive), over half (54%) initially for HIV infection. The overall mean duration of clinical development was 77.2 months, of which 64.6 months was spent in clinical trials before regulatory submission. The total time in clinical development increased from 41.7 months for drugs licensed 1981-1992 to 91.7 months for drugs licensed 2004-2014. This increase was accounted for by an increase in the clinical trials period and not the regulatory approval period, for which there was no observable trend. Drugs initially licensed to treat hepatitis C had a longer duration of clinical development than those indicated for other viral infections. However, the, initially shorter clinical development durations of drugs indicated for HIV infection increased more rapidly across the study period than those indicated for other viral infections. CONCLUSIONS: The time spent by antiviral drugs in clinical development has increased markedly in recent decades despite many initiatives to speed access to innovative new drugs. However, this represents only one part of the translational research pathway, and a complete picture of development timeframes is lacking.

How innovative are new drugs launched in the UK? A retrospective study of new drugs listed in the British National Formulary (BNF) 2001-2012.

OBJECTIVES: Innovative new drugs offer potential benefits to patients, healthcare systems, governments and the pharmaceutical industry. Recent data suggest annual numbers of new drugs launched in the UK have increased in recent years, and we sought to understand whether this represents increasing numbers of highly innovative drugs being made available or the introduction of increasing numbers of drugs with limited additional therapeutic value. DESIGN AND SETTING: Retrospective observational study of new drug entries in the British National Formulary (BNF). PRIMARY AND SECONDARY OUTCOME MEASURES: Number of new drugs launched in the UK each year (based on first appearance in the BNF) from 2001 to 2012, including new chemical entities and new biological drugs, categorised by degree of innovativeness according to published criteria that incorporate both clinical usefulness and the nature of the innovation. RESULTS: Highly innovative, moderately innovative and slightly innovative drugs made up 26%, 18% and 56% of all newly launched drugs, respectively, for the study period (n=290). There was an upward trend in annual numbers of slightly innovative drugs from 2004 onwards (R(2)=0.44), which aligned closely with the recovery in total numbers of new drugs launched each year since that time. There were no discernible time trends in the highly or moderately innovative categories. New drugs for malignancy and skin disease were most likely to be characterised as highly innovative (44% and 57%, respectively). CONCLUSIONS: Highly innovative new drugs comprise only around a quarter of all new drug launches in the UK. In contrast, drugs categorised as only slightly innovative comprised well over half of all new drugs and annual numbers in this category are increasing. Current policy initiatives that seek to increase the supply of innovative new drugs have long-lead times to impact, and will need careful assessment to ensure they deliver their aims without unintended consequences.

The combined influence of distance and neighbourhood deprivation on Emergency Department attendance in a large English population: a retrospective database study.

The frequency of visits to Emergency Departments (ED) varies greatly between populations. This may reflect variation in patient behaviour, need, accessibility, and service configuration as well as the complex interactions between these factors. This study investigates the relationship between distance, socio-economic deprivation, and proximity to an alternative care setting (a Minor Injuries Unit (MIU)), with particular attention to the interaction between distance and deprivation. It is set in a population of approximately 5.4 million living in central England, which is highly heterogeneous in terms of ethnicity, socio-economics, and distance to hospital. The study data set captured 1,413,363 ED visits made by residents of the region to National Health Service (NHS) hospitals during the financial year 2007/8. Our units of analysis were small units of census geography having an average population of 1,545. Separate regression models were made for children and adults. For each additional kilometre of distance from a hospital, predicted child attendances fell by 2.2% (1.7%-2.6% p<0.001) and predicted adult attendances fell by 1.5% (1.2% -1.8%, p<0.001). Compared to the least deprived quintile, attendances in the most deprived quintile more than doubled for children (incident rate ratio (IRR) = 2.19, (1.90-2.54, p<0.001)) and adults (IRR 2.26, (2.01-2.55, p<0.001)). Proximity of an MIU was significant and both adult and child attendances were greater in populations who lived further away from them, suggesting that MIUs may reduce ED demand. The interaction between distance and deprivation was significant. Attendance in deprived neighbourhoods reduces with distance to a greater degree than in less deprived ones for both adults and children. In conclusion, ED use is related to both deprivation and distance, but the effect of distance is modified by deprivation.

At the center of health care policy making: the use of health technology assessment at NICE.

The UK's National Institute for Health and Clinical Excellence (NICE), a world leader in health technology assessment (HTA), sits at the interface of a policy environment where everything is urgent and consensus between policy makers and stakeholders is sometimes difficult to attain. The majority of stakeholder challenges to NICE's use of HTA concern the interpretation of evidence and the methodological rules applied by the appraisal committees. We discuss the most significant issues: choice of comparators; evidence synthesis and indirect comparison; parameter selection, especially for the valuation of quality of life; extrapolation beyond clinical trial data; and the level of the cost-effectiveness threshold.

A simple insightful approach to investigating a hospital standardised mortality ratio: an illustrative case-study.

BACKGROUND: Despite methodological concerns Hospital Standardised Mortality Ratios (HSMRs) are promoted as measures of performance. Hospitals that experience an increase in their HSMR are presented with a serious challenge but with little guidance on how to investigate this complex phenomenon. We illustrate a simple penetrating approach. METHODS: Retrospective analysis of routinely collected hospital admissions data comparing observed and expected deaths predicted by the Dr Foster Unit case mix adjustment method over three years (n = 74,860 admissions) in Shropshire and Telford NHS Trust Hospital (SaTH) constituting PRH (Princess Royal Hospital) and RSH (Royal Shrewsbury Hospital); whose HSMR increased from 99 in the year 2008/09 to 118 in the year 2009/10. RESULTS: The step up in HSMR was primarily located in PRH (109 to 130 vs. 105 to 118 RSH). Disentangling the HSMR by plotting run charts of observed and expected deaths showed that observed deaths were stable in RSH and PRH but expected deaths, especially at PRH, had fallen. The fall in expected deaths has two possible explanations-genuinely lower risk admissions or that the case-mix adjustment model is underestimating the risk of admissions perhaps because of inadequate clinical coding. There was no evidence that the case-mix profile of admissions had changed but there was considerable evidence that clinical coding process at PRH was producing a lower depth of coding resulting in lower expected mortality. CONCLUSION: Knowing whether the change (increase/decrease) in HSMR is driven by the numerator or the denominator is a crucial pivotal first step in understanding a given HSMR and so such information should be an integral part of the HSMR reporting methodology.

Decline in new drug launches: myth or reality? Retrospective observational study using 30 years of data from the UK.

OBJECTIVE: To describe trends in new drugs launched in the UK from 1982 to 2011 and test the hypothesis that the rate of new drug introductions has declined over the study period. There is wide concern that pharmaceutical innovation is declining. Reported trends suggest that fewer new drugs have been launched over recent decades, despite increasing investment into research and development. DESIGN: Retrospective observational study. SETTING AND DATA SOURCE: Database of new preparations added annually to the British National Formulary (BNF). MAIN OUTCOME MEASURES: The number of new drugs entered each year, including new chemical entities(NCEs) and new biological drugs, based on first appearance in the BNF. RESULTS: There was no significant linear trend in the number of new drugs introduced into the UK from 1982 to 2011. Following a dip in the mid-1980s (11-12 NCEs/new biologics introduced annually from 1985 to 1987), there was a variable increase in the numbers of new drugs introduced annually to a peak of 34 in 1997. This peak was followed by a decline to approximately 20 new drugs/year between 2003 and 2006, and another peak in 2010. Extending the timeline further back with existing published data shows an overall slight increase in new drug introductions of 0.16/year over the entire 1971 to 2011 period. CONCLUSIONS: The purported 'innovation dip' is an artefact of the time periods previously studied. Reports of declining innovation need to be considered in the context of their timescale and perspective.

Weekend admission to hospital has a higher risk of death in the elective setting than in the emergency setting: a retrospective database study of national health service hospitals in England.

BACKGROUND: Although acute hospitals offer a twenty-four hour seven day a week service levels of staffing are lower over the weekends and some health care processes may be less readily available over the weekend. Whilst it is thought that emergency admission to hospital on the weekend is associated with an increased risk of death, the extent to which this applies to elective admissions is less well known. We investigated the risk of death in elective and elective patients admitted over the weekend versus the weekdays. METHODS: Retrospective statistical analysis of routinely collected acute hospital admissions in England, involving all patient discharges from all acute hospitals in England over a year (April 2008-March 2009), using a logistic regression model which adjusted for a range of patient case-mix variables, seasonality and admission over a weekend separately for elective and emergency (but excluding zero day stay emergency admissions discharged alive) admissions. RESULTS: Of the 1,535,267 elective admissions, 91.7% (1,407,705) were admitted on the weekday and 8.3% (127,562) were admitted on the weekend. The mortality following weekday admission was 0.52% (7,276/1,407,705) compared with 0.77% (986/127,562) following weekend admission. Of the 3,105,249 emergency admissions, 76.3% (2,369,316) were admitted on the weekday and 23.7% (735,933) were admitted on the weekend. The mortality following emergency weekday admission was 6.53% (154,761/2,369,316) compared to 7.06% (51,922/735,933) following weekend admission. After case-mix adjustment, weekend admissions were associated with an increased risk of death, especially in the elective setting (elective Odds Ratio: 1.32, 95% Confidence Interval 1.23 to 1.41); vs emergency Odds Ratio: 1.09, 95% Confidence Interval 1.05 to 1.13). CONCLUSIONS: Weekend admission appears to be an independent risk factor for dying in hospital and this risk is more pronounced in the elective setting. Given the planned nature of elective admissions, as opposed to the unplanned nature of emergency admissions, it would seem less likely that this increased risk in the elective setting is attributable to unobserved patient risk factors. Further work to understand the relationship between weekend processes of care and mortality, especially in the elective setting, is required.