Analysing cluster randomised controlled trials using GLMM, GEE1, GEE2, and QIF: results from four case studies.

BACKGROUND: Using four case studies, we aim to provide practical guidance and recommendations for the analysis of cluster randomised controlled trials. METHODS: Four modelling approaches (Generalized Linear Mixed Models with parameters estimated by maximum likelihood/restricted maximum likelihood; Generalized Linear Models with parameters estimated by Generalized Estimating Equations (1st order or second order) and Quadratic Inference Function, for analysing correlated individual participant level outcomes in cluster randomised controlled trials were identified after we reviewed the literature. We systematically searched the online bibliography databases of MEDLINE, EMBASE, PsycINFO (via OVID), CINAHL (via EBSCO), and SCOPUS. We identified the above-mentioned four statistical analytical approaches and applied them to four case studies of cluster randomised controlled trials with the number of clusters ranging from 10 to 100, and individual participants ranging from 748 to 9,207. Results were obtained for both continuous and binary outcomes using R and SAS statistical packages. RESULTS: The intracluster correlation coefficient (ICC) estimates for the case studies were less than 0.05 and are consistent with the observed ICC values commonly reported in primary care and community-based cluster randomised controlled trials. In most cases, the four methods produced similar results. However, in a few analyses, quadratic inference function produced different results compared to the generalized linear mixed model, first-order generalized estimating equations, and second-order generalized estimating equations, especially in trials with small to moderate numbers of clusters. CONCLUSION: This paper demonstrates the analysis of cluster randomised controlled trials with four modelling approaches. The results obtained were similar in most cases, however, for trials with few clusters we do recommend that the quadratic inference function should be used with caution, and where possible a small sample correction should be used. The generalisability of our results is limited to studies with similar features to our case studies, for example, studies with a similar-sized ICC. It is important to conduct simulation studies to comprehensively evaluate the performance of the four modelling approaches.

Catheter insertion techniques for improving catheter function and clinical outcomes in peritoneal dialysis patients.

BACKGROUND: Peritoneal dialysis (PD) relies on the optimal functionality of the flexible plastic PD catheter present within the peritoneal cavity to enable effective treatment. As a result of limited evidence, it is uncertain if the PD catheter's insertion method influences the rate of catheter dysfunction and, thus, the quality of dialysis therapy. Numerous variations of four basic techniques have been adopted in an attempt to improve and maintain PD catheter function. This review evaluates the association between PD catheter insertion technique and associated differences in  PD catheter function and post-PD catheter insertion complications OBJECTIVES: Our aims were to 1) evaluate if a specific technique used for PD catheter insertion has lower rates of PD catheter dysfunction (early and late) and technique failure; and 2) examine if any of the available techniques results in a reduction in post-procedure complication rates including postoperative haemorrhage, exit-site infection and peritonitis. SEARCH METHODS: We searched the Cochrane Kidney and Transplant Register of Studies up to 24 November 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. SELECTION CRITERIA: We included randomised controlled trials (RCTs) examining adults and children undergoing PD catheter insertion. The studies examined any two PD catheter insertion techniques, including laparoscopic, open-surgical, percutaneous and peritoneoscopic insertion. Primary outcomes of interest were PD catheter function and technique survival.  DATA COLLECTION AND ANALYSIS: Two authors independently performed data extraction and assessed the risk of bias for all included studies. Main outcomes in the Summary of Findings tables include primary outcomes - early PD catheter function, long-term PD catheter function, technique failure and postoperative complications. A random effects model was used to perform meta-analyses; risk ratios (RRs) were calculated for dichotomous outcomes, and mean differences (MD) were calculated for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. The certainty of the evidence was evaluated using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach.  MAIN RESULTS: Seventeen studies were included in this review. Nine studies were suitable for inclusion in quantitative meta-analysis (670 randomised participants). Five studies compared laparoscopic with open PD catheter insertion, and four studies compared a 'medical' insertion technique with open surgical PD catheter insertion: percutaneous (2) and peritoneoscopic (2). Random sequence generation was judged to be at low risk of bias in eight studies. Allocation concealment was reported poorly, with only five studies judged to be at low risk of selection bias. Performance bias was judged to be high risk in 10 studies. Attrition bias and reporting bias were judged to be low in 14 and 12 studies, respectively. Six studies compared laparoscopic PD catheter insertion with open surgical insertion. Five studies could be meta-analysed (394 participants). For our primary outcomes, data were either not reported in a format that could be meta-analysed (early PD catheter function, long-term catheter function) or not reported at all (technique failure). One death was reported in the laparoscopic group and none in the open surgical group. In low certainty evidence, laparoscopic PD catheter insertion may make little or no difference to the risk of peritonitis (4 studies, 288 participants: RR 0.97, 95% CI 0.63 to 1.48; I² = 7%), PD catheter removal (4 studies, 257 participants: RR 1.15, 95% CI 0.80 to 1.64; I² = 0%), and dialysate leakage (4 studies, 330 participants: RR 1.40, 95% CI 0.49 to 4.02; I² = 0%), but may reduce the risk of haemorrhage (2 studies, 167 participants: RR 1.68, 95% CI 0.28 to 10.31; I² = 33%) and catheter tip migration (4 studies, 333 participants: RR 0.43, 95% CI 0.20 to 0.92; I² = 12%). Four studies compared a medical insertion technique with open surgical insertion (276 participants). Technique failure was not reported, and no deaths were reported (2 studies, 64 participants). In low certainty evidence, medical insertion may make little or no difference to early PD catheter function (3 studies, 212 participants: RR 0.73, 95% CI 0.29 to 1.83; I² = 0%), while one study reported long-term PD function may improve with peritoneoscopic insertion (116 participants: RR 0.59, 95% CI 0.38 to 0.92). Peritoneoscopic catheter insertion may reduce the episodes of early peritonitis (2 studies, 177 participants: RR 0.21, 95% CI 0.06 to 0.71; I² = 0%) and dialysate leakage (2 studies, 177 participants: RR 0.13, 95% CI 0.02 to 0.71; I² = 0%). Medical insertion had uncertain effects on catheter tip migration (2 studies, 90 participants: RR 0.74, 95% CI 0.15 to 3.73; I² = 0%). Most of the studies examined were small and of poor quality, increasing the risk of imprecision. There was also a significant risk of bias therefore cautious interpretation of results is advised. AUTHORS' CONCLUSIONS: The available studies show that the evidence needed to guide clinicians in developing their PD catheter insertion service is lacking. No PD catheter insertion technique had lower rates of PD catheter dysfunction. High-quality, evidence-based data are urgently required, utilising multi-centre RCTs or large cohort studies, in order to provide definitive guidance relating to PD catheter insertion modality.

A descriptive study of samples sizes used in agreement studies published in the PubMed repository.

INTRODUCTION: A sample size justification is required for all studies and should give the minimum number of subjects to be recruited for the study to achieve its primary objective. The aim of this review is to describe sample sizes from agreement studies with continuous or categorical endpoints and different methods of assessing agreement, and to determine whether sample size justification was provided. METHODS: Data were gathered from the PubMed repository with a time interval of 28th September 2018 to 28th September 2020. The search returned 5257 studies of which 82 studies were eligible for final assessment after duplicates and ineligible studies were excluded. RESULTS: We observed a wide range of sample sizes. Forty-six studies (56%) used a continuous outcome measure, 28 (34%) used categorical and eight (10%) used both. Median sample sizes were 50 (IQR 25 to 100) for continuous endpoints and 119 (IQR 50 to 271) for categorical endpoints. Bland-Altman limits of agreement (median sample size 65; IQR 35 to 124) were the most common method of statistical analysis for continuous variables and Kappa coefficients for categorical variables (median sample size 71; IQR 50 to 233). Of the 82 studies assessed, only 27 (33%) gave justification for their sample size. CONCLUSIONS: Despite the importance of a sample size justification, we found that two-thirds of agreement studies did not provide one. We recommend that all agreement studies provide rationale for their sample size even if they do not include a formal sample size calculation.

Non-urgent emergency department attendances in children: a retrospective observational analysis.

INTRODUCTION: A significant proportion of ED attendances in children may be non-urgent attendances (NUAs), which could be better managed elsewhere. This study aimed to quantify NUAs and urgent attendances (UAs) in children to ED and determine which children present in this way and when. METHODS: Dataset extracted from the CUREd research database containing linked data on the provision of care in Yorkshire and Humber. Analysis focused on children's ED attendances (April 2014-March 2017). Summary statistics and odds ratios (OR) comparing NUAs and UAs were examined by: age, mode and time of arrival and deprivation alongside comparing summary statistics for waiting, treatment and total department times. RESULTS: NUAs were more likely in younger children: OR for NUA in children aged 1-4 years, 0.82 (95% CI: 0.80 to 0.83), age 15 years, 0.39 (95% CI: 0.38 to 0.40), when compared with those under 1 year. NUAs were more likely to arrive out of hours (OOHs) compared with in hours: OR 1.19 (95% CI 1.18 to 1.20), and OOHs arrivals were less common in older children compared with those under 1 year: age 1-4 years, 0.87 (95% CI: 0.84 to 0.89) age 15 years, 0.66 (95% CI: 0.63 to 0.69). NUAs also spent less total time in the ED, with a median (IQR) of 98 min (60-147) compared with 127 min (80-185) for UAs. CONCLUSION: A substantial proportion of ED attendances in children are NUAs. Our data suggest there are particular groups of children for whom targeted interventions would be most beneficial. Children under 5 years would be such a group, particularly in providing accessible, timely care outside of usual community care opening hours.

Paediatric emergency department utilisation rates and maternal migration status in the Born in Bradford cohort: A cross-sectional study.

BACKGROUND: Globally, international migration is increasing. Population growth, along with other demographic changes, may be expected to put new pressures on healthcare systems. Some studies across Europe suggest that emergency departments (EDs) are used more, and differently, by migrants compared to non-migrant populations, which may be a result of unfamiliarity with the healthcare systems and difficulties accessing primary healthcare. However, little evidence exists to understand how migrant parents, who are typically young and of childbearing age, utilise EDs for their children. This study aimed to examine the association between paediatric ED utilisation in the first 5 years of life and maternal migration status in the Born in Bradford (BiB) cohort study. METHODS AND FINDINGS: We analysed linked data from the BiB study-an ongoing, multi-ethnic prospective birth cohort study in Bradford. Bradford is a large, ethnically diverse city in the north of England. In 2017, more than a third of births in Bradford were to mothers who were born outside the UK. Between March 2007 and December 2010, pregnant women were recruited to BiB during routine antenatal care, and the children born to these mothers have been, and continue to be, followed over time to assess how social, genetic, environmental, and behavioural factors impact on health from childhood to adulthood. Data analysed in this study included baseline questionnaire data from BiB mothers, and Bradford Royal Infirmary ED episode data for their children. Main outcomes were likelihood of paediatric ED use (no visits versus at least 1 ED visit in the first 5 years of life) and ED utilisation rates (number and frequency of ED visits) for children who have accessed the ED. The main explanatory variable was mother's migrant status (foreign-born versus UK/Irish-born). Multivariable analyses (logistic and zero-truncated negative binomial regression) were conducted adjusting for socio-demographic and socio-economic factors. The final dataset included 10,168 children born between April 2007 and June 2011, of whom 35.6% were born to migrant mothers. Foreign-born mothers originated from South Asia (28.6%), Europe/Central Asia (3.2%), Africa (2.1%), East Asia/Pacific (1.1%), and the Middle East (0.6%). At recruitment the mothers ranged in age from 15 to 49 years old. Overall, 3,104 (30.5%) children had at least 1 ED visit in the first 5 years of life, with the highest proportion of visits being in the first year of life (36.7%). The proportion of children who visited the ED at least once was lower for children of migrant mothers as compared to children of non-migrant mothers (29.4% versus 31.2%). Children of migrant mothers were found to be less likely to visit the ED (odds ratio 0.88 [95% CI 0.80 to 0.97], p = 0.012). However, among children who visited the ED, the utilisation rate was significantly higher for children of migrant mothers (incidence rate ratio [IRR] 1.19 [95% CI 1.01 to 1.40], p = 0.040). Utilisation rates were higher for children born to mothers from Europe (IRR 1.71 [95% CI 1.07 to 2.71], p = 0.024) and established migrants (≥5 years living in UK) (IRR 1.24 [95% CI 1.02 to 1.51], p = 0.032) compared to UK/Irish-born mothers. Important limitations include being unable to measure children's underlying health status and the urgency of ED attendance, as well as the analysis being limited by missing data. CONCLUSIONS: In this study we observed that there is no higher likelihood of first paediatric ED attendance in the first 5 years of life for children in the BiB cohort for migrant mothers. However, among ED users, children of migrant mothers attend the service more frequently than children of UK/Irish-born mothers. Our findings show that patterns of ED utilisation differ by mother's region of origin and time since arrival in the UK.

The prevalence and natural history of normocalcaemic hypoparathyroidism in a United Kingdom referral population.

CONTEXT: Normocalcaemic hypoparathyroidism (NHYPO) is characterized by low levels of parathyroid hormone (PTH) with normal levels of calcium. There is little in the current literature on this disease, with only two studies published on its prevalence, while its natural history remains relatively unknown. OBJECTIVES: To identify the prevalence of NHYPO in a UK referral population and to study the natural history of the disorder. DESIGN: Retrospective study. Five-year follow-up. PATIENTS: 6280 patients referred for a BMD measurement in a Metabolic Bone referral centre. MEASUREMENTS: Prevalence of NHYPO and variability of calcium. RESULTS: Based on laboratory results on the index day, 22 patients with NHYPO were identified. Four patients were excluded due to non-PTH-induced hypocalcaemia and unconfirmed data. The final prevalence was 0.29%. Only 67% had persistent normocalcaemia, and the rest had intermittent hypocalcaemia. Two of these patients also had persistently low PTH on two occasions. Most of the patients had one PTH measurement available. No patient developed permanent hypoparathyroidism. CONCLUSIONS: The prevalence calculated from this UK referral population is lower when compared to results from previous studies. NHYPO patients often have episodes of hypocalcaemia with some cases having no apparent reason for calcium levels below the reference range.

Outcomes for Patients Who Contact the Emergency Ambulance Service and Are Not Transported to the Emergency Department: A Data Linkage Study.

Objectives: Emergency ambulance services do not transport all patients to hospital. International literature reports non-transport rates ranging from 3.7-93.7%. In 2017, 38% of the 11 million calls received by ambulance services in England were attended by ambulance but not transported to an Emergency Department (ED). A further 10% received clinical advice over the telephone. Little is known about what happens to patients following a non-transport decision. We aimed to investigate what happens to patients following an emergency ambulance telephone call that resulted in a non-transport decision, using a linked routine data-set. Methods: Six-months individual patient level data from one ambulance service in England, linked with Hospital Episode Statistics and national mortality data, were used to identify subsequent health events (ambulance re-contact, ED attendance, hospital admission, death) within 3 days (primary analysis) and 7 days (secondary analysis) of an ambulance call ending in non-transport to hospital. Non-clinical staff used a priority dispatch system e.g. Medical Priority Dispatch System to prioritize calls for ambulance dispatch. Non-transport to ED was determined by ambulance crew members at scene or clinicians at the emergency operating center when an ambulance was not dispatched (telephone advice). Results: The data linkage rate was 85% for patients who were discharged at scene (43,108/50,894). After removal of deaths associated with end of life care (N = 312), 9% (3,861/42,796) re-contacted the ambulance service, 12.6% (5,412/42,796) attended ED, 6.3% (2,694/42,796) were admitted to hospital, and 0.3% (129/42,796) died within 3 days of the call. Rates were higher for events occurring within 7 days. For example, 12% re-contacted the ambulance service, 16.1% attended ED, 9.3% were admitted to hospital, and 0.5% died. The linkage rate for telephone advice calls was low because ambulance services record less information about these patients (24% 2,514/10,634). A sensitivity analysis identified a range of subsequent event rates: 2.5-10.5% of patients were admitted to hospital and 0.06-0.24% of patient died within 3 days of the call. Conclusions: Most non-transported patients did not have subsequent health events. Deaths after non-transport are an infrequent event that could be selected for more detailed review of individual cases, to facilitate learning and improvement.

Exploring the characteristics, acuity and management of adult ED patients at night-time.

OBJECTIVES: ED care is required for acutely unwell and injured patients 24 hours a day, 7 days a week. The aim of this study was to compare characteristics and activity of type 1 ED attendances according to whether their time of arrival was during the day (08:00-18:00) or at night (18:00-08:00). METHODS: Hospital Episode Statistics (HES) data from NHS Digital for all A&E and admitted patient care activity provided by all acute (not mental health or primary care) NHS hospital trusts in Yorkshire and Humber (1 April 2011 to 31 March 2014) for adult patients were analysed. Adjusted linear and logistic regression was used to model the data. RESULTS: Adjusted regression analysis results show that patients who attended ED at night waited an extra 18.76 (95% CI 18.62 to 18.89) min to be seen by a clinician. They also spent an additional 13.64 (95% CI 13.47 to 13.81) min total in ED. Patients who attended at night were OR 2.20 (95% CI 2.17 to 2.23) times more likely to leave without being seen. They were also OR 1.26 (95% CI 1.25 to 1.27) times more likely to re-attend the ED and were OR 1.20 (95% CI 1.19 to 1.21) times more likely to present with non-urgent conditions. Overnight patients were more likely to be admitted to hospital, OR 1.09 (95% CI 1.09 to 1.10) times, however, those admitted were more likely to have a short-stay admission. CONCLUSION: There is an 'overnight effect' of patients attending EDs. Patients wait longer, leave without being seen, attend with non-urgent problems and are more likely to be admitted for a short stay. Further work is required to identify the potential underlying causes of these differences.

Urgent care axis for the older adult: where is best to target interventions?

BACKGROUND: We explored the urgent care axis across EDs in Yorkshire and Humber (Y&H) for patients aged ≥75 years to identify where interventions could be targeted to prevent ED attendances and inpatient admissions. METHODS: Hospital Episode Statistics (HES) data for attendances across 18 EDs in Y&H from April 2011 to March 2014 were retrospectively analysed. HES A&E and Admitted Patient Care patient records data were linked to describe the entire patient pathway. The population studied was adult patients attending type 1 EDs, comparing those ≥75 years with those under 75. Data analysed included arrival mode, presentation time, time in ED, outcome (admitted/discharged), admission length of stay, International Classification of Diseases 10th Revision (ICD-10) and cause codes related to admission. Short-stay admissions and admissions with potentially avoidable conditions (identified by ICD-10 codes and cause codes) were identified. Comparative analysis was undertaken between sites. RESULTS: There were 3 736 541 ED attendances, of which 625 772 (16.7%) were ≥75 years. Older patients were significantly more likely to attend via ambulance than the younger cohort (OR 7.7, 95% CI 7.6 to 7.7), and had significantly longer median stays within ED (195 vs 136 min, p<0.001) and increased likelihood of admission (OR 4.5, 95% CI 4.5 to 4.6). Short-stay admissions accounted for 28.3% of older adult admissions. 37.3% of older adult admissions were with conditions that were potentially avoidable, accounting for 42.3% of short-stay admissions. There was regional variation in the proportions of older adults admitted (between 34.3% and 40.9%). DISCUSSION: Large numbers of older adults present to EDs mainly by ambulance. Significant proportions are admitted for short periods with conditions that might potentially be managed outside of hospital. Variation across the region warrants further study.

Altered cortical microarchitecture in patients with monoclonal gammopathy of undetermined significance.

Patients with monoclonal gammopathy of undetermined significance (MGUS) are at increased fracture risk, and we have previously shown that MGUS patients have altered trabecular bone microarchitecture compared with controls. However, there are no data on whether the porosity of cortical bone, which may play a greater role in bone strength and the occurrence of fractures, is increased in MGUS. Thus, we studied cortical porosity and bone strength (apparent modulus) using high-resolution peripheral quantitative computed tomography imaging of the distal radius in 50 MGUS patients and 100 age-, gender-, and body mass index-matched controls. Compared with controls, MGUS patients had both significantly higher cortical porosity (+16.8%; P < .05) and lower apparent modulus (-8.9%; P < .05). Despite their larger radial bone size, MGUS patients have significantly increased cortical bone porosity and reduced bone strength relative to controls. This increased cortical porosity may explain the increased fracture risk seen in MGUS patients.

The impact of surgery for vulval cancer upon health-related quality of life and pelvic floor outcomes during the first year of treatment: a longitudinal, mixed methods study.

OBJECTIVE: To measure the long-term impact of surgical treatment for vulval cancer upon health-related quality of life and pelvic floor outcomes during the first year of therapy. METHODS: Prospective, longitudinal, mixed-methods study. Twenty-three women aged >18 years with a new diagnosis of vulval cancer were recruited. The EORTC QLQ C30, SF-36 and an electronic pelvic floor assessment questionnaire (ePAQ-PF) were administered at baseline (pre-treatment) and 3, 6, 9 and 12 months post-treatment. Mixed effects repeated measures models (all adjusted for age and BMI) were used to investigate changes over time and differences between cancer stage. Qualitative interviews were carried out with 11 of the women and analysed using a thematic approach. RESULTS: Mean age was 59.9 years (SD = 15.3; range = 23.8-86.6 yrs). Mean BMI was 30.0 (SD = 4.5; range = 24.4-38.2). Sixteen women had early (Stage 1 to 2B), and seven women had advanced stage disease (Stage 3 to 4B). Questionnaire scores revealed that physical and social functioning, fatigue, pain and general sex life were significantly worse at 12 months than pre-treatment (p = < 0.05). Qualitative analysis revealed multiple treatment side effects which were perceived as severe and enduring. Women with advanced vulval cancer had significantly worse SF-36 mental health scores at 12 months compared to women with early stage disease (p = 0.037). CONCLUSIONS: Surgery for vulval cancer has long-term implications which can be persistent 12 months post-treatment. High rates of morbidity relating to lymphoedema and sexual function re-enforce the need for specialist clinics to support women who suffer these complications. © 2015 The Authors. Psycho-Oncology published by John Wiley & Sons Ltd.

COST-EFFECTIVENESS OF STRUCTURED EDUCATION IN CHILDREN WITH TYPE-1 DIABETES MELLITUS.

OBJECTIVES: Kids in Control OF Food (KICk-OFF) is a 5-day structured education program for 11- to 16-year-olds with type 1 diabetes mellitus (T1DM) who are using multiple daily insulin injections. This study evaluates the cost-effectiveness of the KICk-OFF education program compared with the usual care using data from the KICk-OFF trial. METHODS: The short-term within-trial analysis covers the 2-year postintervention period. Data on glycated hemoglobin (HbA1c), severe hypoglycemia, and diabetic ketoacidosis (DKA) were collected over a 2-year follow-up period. Sub-group analyses have been defined on the basis of baseline HbA1c being below 7.5 percent (58.5 mmol/mol) (low group), between 7.5 percent and 9.5 percent (80.3 mmol/mol) (medium group), and over 9.5 percent (high group). The long-term cost-effectiveness evaluation has been conducted by using The Sheffield Type 1 Diabetes Policy Model, which is a patient-level simulation model on T1DM. It includes long-term microvascular (retinopathy, neuropathy, and nephropathy) and macrovascular (myocardial infarction, stroke, revascularization, and angina) diabetes-related complications and acute adverse events (severe hypoglycemia and DKA). RESULTS: The most favorable within-trial scenario for the KICk-OFF arm led to an incremental cost-effectiveness ratio (ICER) of £23,688 (base year 2009) with a cost-effectiveness probability of 41.3 percent. Simulating the long-term complications using the full cohort data, the mean ICER for the base case was £28,813 (base year 2011) and the probability of the KICk-OFF intervention being cost-effective at £20,000/QALY threshold was 42.6 percent, with considerable variation due to treatment effect duration. For the high HbA1c sub-group, the KICk-OFF arm was "dominant" (meaning it provided better health gains at lower costs than usual care) over the usual care arm in each scenario considered. CONCLUSIONS: For the whole study population, the cost-effectiveness of KICk-OFF depends on the assumption for treatment effect duration. For the high baseline HbA1c sub-group, KICk-OFF arm was estimated to be dominant over the usual care arm regardless of the assumption on the treatment effect duration.

Normocalcaemic hypoparathyroidism: prevalence and effect on bone status in older women. The OPUS study.

OBJECTIVE: There are no consistent data on the prevalence and bone status of normocalcaemic hypoparathyroidism (NHYPO) as defined by normal adjusted calcium and low PTH level. Our aim was to determine the prevalence and the metabolic bone profile of NHYPO in older women, assessing its evolution over time. The second objective was to evaluate the prevalence of other calcium metabolic disorders. DESIGN: The Osteoporosis and Ultrasound Study (OPUS) is a 6-yr prospective study of fracture-related factors. PARTICIPANTS: A total of 2419 older women (age 55-79 yrs) and 258 younger women (age 30-40 yrs) participated. Complete follow-up data were available in 1416 subjects. MEASUREMENTS: After calculating the adjusted calcium according to James' formula, we identified 'abnormal' calcium and PTH using Mahalanobis distances and allocated older women into different pathological categories using reference intervals from the healthy young women. RESULTS: We identified 57 subjects with NHYPO (2·4%). These women had lower than expected bone turnover as assessed by bone alkaline phosphatase (-14·5%, 95% CI: -26·2 to -3·0, P = 0·007), CTX (-66·3%, 95% CI: -74·0 to -56·4, P < 0·001) and osteocalcin (-36·8%, 95% CI: -45·6 to -26·6, P < 0·001). After 6 years, of the 35 NHYPO subjects with follow-up data, none developed overt hypoparathyroidism and only 15 (0·6%) subjects had persistent evidence of NHYPO. We also identified 86 subjects (3·6%) affected by hyperparathyroid hypercalcaemia. CONCLUSION: This is the first large population-based study to investigate NHYPO in older women. NHYPO is fairly common, not always persistent and is characterized by low bone turnover.

Dynamin function is important for chemokine receptor-induced cell migration.

The HIV viral entry co-receptors CCR5 and CXCR4 function physiologically as typical chemokine receptors. Activation leads to cytosolic signal transduction that results in a variety of cellular responses such as cytoskeletal rearrangement and chemotaxis (CTX). Our aim was to investigate the signalling pathways involved in CC and CXC receptor-mediated cell migration. Inhibition of dynamin I and II GTPase with dynasore completely inhibited CCL3-stimulated CTX in THP-1 cells, whereas the dynasore analogue Dyngo-4a, which is a more potent inhibitor, showed reduced ability to inhibit CC chemokine-induced CTX. In contrast, dynasore was not able to block cell migration via CXCR4. The same activation/inhibition pattern was verified in activated T lymphocytes for different CC and CXC chemokines. Cell migration induced by CC and CXC receptors does not rely on active internalization processes driven by dynamin because the blockade of internalization does not affect migration, but it might rely on dynamin interaction with the cytoskeleton. We identify here a functional difference in how CC and CXC receptor migration is controlled, suggesting that specific signalling networks are being employed for different receptor classes and potentially specific therapeutic targets to prevent receptor migration can be identified.

Rapid-throughput skeletal phenotyping of 100 knockout mice identifies 9 new genes that determine bone strength.

Osteoporosis is a common polygenic disease and global healthcare priority but its genetic basis remains largely unknown. We report a high-throughput multi-parameter phenotype screen to identify functionally significant skeletal phenotypes in mice generated by the Wellcome Trust Sanger Institute Mouse Genetics Project and discover novel genes that may be involved in the pathogenesis of osteoporosis. The integrated use of primary phenotype data with quantitative x-ray microradiography, micro-computed tomography, statistical approaches and biomechanical testing in 100 unselected knockout mouse strains identified nine new genetic determinants of bone mass and strength. These nine new genes include five whose deletion results in low bone mass and four whose deletion results in high bone mass. None of the nine genes have been implicated previously in skeletal disorders and detailed analysis of the biomechanical consequences of their deletion revealed a novel functional classification of bone structure and strength. The organ-specific and disease-focused strategy described in this study can be applied to any biological system or tractable polygenic disease, thus providing a general basis to define gene function in a system-specific manner. Application of the approach to diseases affecting other physiological systems will help to realize the full potential of the International Mouse Phenotyping Consortium.

Prediction modelling for trauma using comorbidity and 'true' 30-day outcome.

BACKGROUND: Prediction models for trauma outcome routinely control for age but there is uncertainty about the need to control for comorbidity and whether the two interact. This paper describes recent revisions to the Trauma Audit and Research Network (TARN) risk adjustment model designed to take account of age and comorbidities. In addition linkage between TARN and the Office of National Statistics (ONS) database allows patient's outcome to be accurately identified up to 30 days after injury. Outcome at discharge within 30 days was previously used. METHODS: Prospectively collected data between 2010 and 2013 from the TARN database were analysed. The data for modelling consisted of 129 786 hospital trauma admissions. Three models were compared using the area under the receiver operating curve (AuROC) for assessing the ability of the models to predict outcome, the Akaike information criteria to measure the quality between models and test for goodness-of-fit and calibration. Model 1 is the current TARN model, Model 2 is Model 1 augmented by a modified Charlson comorbidity index and Model 3 is Model 2 with ONS data on 30 day outcome. RESULTS: The values of the AuROC curve for Model 1 were 0.896 (95% CI 0.893 to 0.899), for Model 2 were 0.904 (0.900 to 0.907) and for Model 3 0.897 (0.896 to 0.902). No significant interaction was found between age and comorbidity in Model 2 or in Model 3. CONCLUSIONS: The new model includes comorbidity and this has improved outcome prediction. There was no interaction between age and comorbidity, suggesting that both independently increase vulnerability to mortality after injury.

Variation in centre-specific survival in patients starting renal replacement therapy in England is explained by enhanced comorbidity information from hospitalization data.

BACKGROUND: Unadjusted survival on renal replacement therapy (RRT) varies widely from centre to centre in England. Until now, missing data on case mix have made it impossible to determine whether this variation reflects genuine differences in the quality of care. Data linkage has the capacity to reduce missing data. METHODS: Modelling of survival using Cox proportional hazards of data returned to the UK Renal Registry on patients starting RRT for established renal failure in England. Data on ethnicity, socioeconomic status and comorbidity were obtained by linkage to the Hospital Episode Statistics database, using data from hospitalizations prior to starting RRT. RESULTS: Patients with missing data were reduced from 61 to 4%. The prevalence of comorbid conditions was remarkably similar across centres. When centre-specific survival was compared after adjustment solely for age, survival was below the 95% limit for 6 of 46 centres. The addition of variables into the multivariable model altered the number of centres that appeared to be 'outliers' with worse than expected survival as follows: ethnic origin four outliers, socioeconomic status eight outliers and year of the start of RRT four outliers. The addition of a combination of 16 comorbid conditions present at the start of RRT reduced the number of centres with worse than expected survival to one. CONCLUSIONS: Linked data between a national registry and hospital admission dramatically reduced missing data, and allowed us to show that nearly all the variation between English renal centres in 3-year survival on RRT was explained by demographic factors and by comorbidity.

The statistical interpretation of pilot trials: should significance thresholds be reconsidered?

BACKGROUND: In an evaluation of a new health technology, a pilot trial may be undertaken prior to a trial that makes a definitive assessment of benefit. The objective of pilot studies is to provide sufficient evidence that a larger definitive trial can be undertaken and, at times, to provide a preliminary assessment of benefit. METHODS: We describe significance thresholds, confidence intervals and surrogate markers in the context of pilot studies and how Bayesian methods can be used in pilot trials. We use a worked example to illustrate the issues raised. RESULTS: We show how significance levels other than the traditional 5% should be considered to provide preliminary evidence for efficacy and how estimation and confidence intervals should be the focus to provide an estimated range of possible treatment effects. We also illustrate how Bayesian methods could also assist in the early assessment of a health technology. CONCLUSIONS: We recommend that in pilot trials the focus should be on descriptive statistics and estimation, using confidence intervals, rather than formal hypothesis testing and that confidence intervals other than 95% confidence intervals, such as 85% or 75%, be used for the estimation. The confidence interval should then be interpreted with regards to the minimum clinically important difference. We also recommend that Bayesian methods be used to assist in the interpretation of pilot trials. Surrogate endpoints can also be used in pilot trials but they must reliably predict the overall effect on the clinical outcome.

The Intersection of a Child's Demographics and Household Socioeconomic Status in the Multimorbidity of Malaria, Anaemia, and Malnutrition among Children Aged 6-59 Months in Nigeria.

Multimorbidity of malaria, anemia, and malnutrition (MAMM) is a condition in which an individual has two or more of these health conditions, and is becoming an emergent public health concern in sub-Saharan African countries. The independent associations of a child's demographic variables and household socioeconomic (HSE) disparities with a child's health outcomes have been established in the literature. However, the effects of the intersection of these factors on MAMM, while accounting for other covariates, have not been studied. Therefore, this study aimed to determine how children's sex, age, and household socioeconomic status interact to explain the variations in MAMM among children aged 6-59 months in Nigeria. Data from the 2018 Nigeria Demographic and Health Survey and the 2018 National Human Development Report (NHDR) were used. This study included weighted samples of 10,184 children aged 6-59 months in Nigeria. A three-level multilevel mixed effect ordinal logistic regression model was used, such that individual characteristics at level 1 were nested in communities at level 2 and nested in states at level 3. Subsequently, predictive probability charts and average adjusted probability tables were used to interpret the intersectional effects. Five models were created in this scenario. Model 1 is the interaction between the child's sex and household wealth status; model 2 is the interaction between the child's sex and age; model 3 is the interaction between the child's age and household wealth status; model 4 has the three two-way interactions of the child's sex, age, and household wealth status; and model 5 includes model 4 and the three-way interactions between a child's sex, age, and household wealth quintiles; while accounting for other covariates in each of the models. The prevalence of children with a 'none of the three diseases' outcome was 17.3% (1767/10,184), while 34.4% (3499/10,184) had 'only one of the diseases', and 48.3% (4918/10,184) had 'two or more' MAMMs. However, in the multivariate analyses, model 3 was the best fit compared with other models, so the two-way interaction effects of a child's age and household wealth status are significant predictors in the model. Children aged 36-47 months living in the poorest households had a probability of 0.11, 0.18, and 0.32 of existing with MAMM above the probability of children of the same age who live in the middle class, more prosperous, and richest households, respectively, while all other covariates were held constant. Thus, the variation in the prevalence of MAMM in children of different ages differs depending on the household wealth quintile. In other words, in older children, the variations in MAMM become more evident between the richer and the poorer household quintiles. Therefore, it is recommended that policies that are geared toward economic redistribution will help bridge the disparities observed in the prevalence of multiple diseases among children aged 6-59 months in Nigeria.

Comparison of statistical methods for the analysis of patient-reported outcomes in randomised controlled trials: A simulation study.

Patient-reported outcomes (PROs) that aim to measure patients' subjective attitudes towards their health or health-related conditions in various fields have been increasingly used in randomised controlled trials (RCTs). PRO data is likely to be bounded, discrete, and skewed. Although various statistical methods are available for the analysis of PROs in RCT settings, there is no consensus on what statistical methods are the most appropriate for use. This study aims to use simulation methods to compare the performance (in terms of bias, empirical standard error, coverage of the confidence interval, Type I error, and power) of three different statistical methods, multiple linear regression (MLR), Tobit regression (Tobit), and median regression (Median), to estimate a range of predefined treatment effects for a PRO in a two-arm balanced RCT. We assumed there was an underlying latent continuous outcome that the PRO was measuring, but the actual scores observed were equally spaced and discrete. This study found that MLR was associated with little bias of the estimated treatment effect, small standard errors, and appropriate coverage of the confidence interval under most scenarios. Tobit performed worse than MLR for analysing PROs with a small number of levels, but it had better performance when analysing PROs with more discrete values. Median showed extremely large bias and errors, associated with low power and coverage for most scenarios especially when the number of possible discrete values was small. We recommend MLR as a simple and universal statistical method for the analysis of PROs in RCT settings.