A Principled Approach to Adjust for Unmeasured Time-Stable Confounding of Supervised Treatment.

We propose a novel method to adjust for unmeasured time-stable confounding when the time between consecutive treatment administrations is fixed. We achieve this by focusing on a new-user cohort. Furthermore, we envisage that all time-stable confounding goes through the potential time on treatment as dictated by the disease condition at the initiation of treatment.

Sagittal Knee Gait Changes After Medial Unicompartmental and Total Knee Arthroplasty: An Exploratory Analysis of 32 Patients.

Background: This study aimed to investigate postoperative developments of sagittal knee gait in a population of knee arthroplasty patients randomized to either unicompartmental or total knee arthroplasty. We hypothesized that knee arthroplasty patients develop greater walking speeds, range of motion, sagittal knee angle velocities, and sagittal knee angle accelerations.

Methods: Thirty-two patients were recruited from a randomized trial comparing the two implant types.

Effect modification between HLA-F and CD56 markers reveals differences in survival for triple-negative breast cancer patients.

Triple-negative breast cancer (TNBC) is usually aggressive and challenging to treat. With high tumour immunogenicity TNBC patients might benefit from immunotherapy. We evaluated heterogeneous immune profiles of individual tumours in relation to clinical development to identify immune markers and their mutual expression.

The Natural History of Crohn's Disease Leading to Intestinal Failure: A Longitudinal Cohort Study from 1973 to 2018.

Background And Aims: The natural history of Crohn's disease leading to intestinal failure is not well characterised. This study aims to describe the clinical course of Crohn's disease preceding intestinal failure and compare disease course and burden between Crohn's disease patients with and without intestinal failure.

Methods: Patients with Crohn's disease complicated by intestinal failure from Rigshospitalet, Copenhagen (n=182) and a nationwide Danish Crohn's disease cohort without intestinal failure (n=22,845) were included.

Propensity weighting plus adjustment in proportional hazards model is not doubly robust.

Recently, it has become common for applied works to combine commonly used survival analysis modeling methods, such as the multivariable Cox model and propensity score weighting, with the intention of forming a doubly robust estimator of an exposure effect hazard ratio that is unbiased in large samples when either the Cox model or the propensity score model is correctly specified. This combination does not, in general, produce a doubly robust estimator, even after regression standardization, when there is truly a causal effect. We demonstrate via simulation this lack of double robustness for the semiparametric Cox model, the Weibull proportional hazards model, and a simple proportional hazards flexible parametric model, with both the latter models fit via maximum likelihood.

APOE Genotype, ApoE Plasma Levels, Lipid Metabolism, and Cognition in Monozygotic Twins with, at Risk of, and without Affective Disorders.

: Lipids influence brain function and mental health. Understanding the role of apolipoproteins in affective disorders could provide valuable insights and potentially pave the way for novel therapeutic approaches. We examined the apolipoprotein E genotype and ApoE-levels, lipid profiles, and the correlation with cognition in 204 monozygotic (MZ) twins with unipolar or bipolar disorder in remission or partial remission (affected, AT), their unaffected co-twins (high-risk, HR), and twins with no personal or family history of affective disorder (low-risk, LR).

Simulation-based sample size calculations of marginal proportional means models for recurrent events with competing risks.

In randomised controlled trials, the outcome of interest could be recurrent events, such as hospitalisations for heart failure. If mortality rates are non-negligible, both recurrent events and competing terminal events need to be addressed when formulating the estimand and statistical analysis is no longer trivial. In order to design future trials with primary recurrent event endpoints with competing risks, it is necessary to be able to perform power calculations to determine sample sizes.

Unbiased and efficient estimation of causal treatment effects in crossover trials.

We introduce causal inference reasoning to crossover trials, with a focus on thorough QT (TQT) studies. For such trials, we propose different sets of assumptions and consider their impact on the modeling strategy and estimation procedure. We show that unbiased estimates of a causal treatment effect are obtained by a g-computation approach in combination with weighted least squares predictions from a working regression model.

Prediction of herpes virus infections after solid organ transplantation: a prospective study of immune function.

Introduction: Herpes virus infections are a major concern after solid organ transplantation and linked to the immune function of the recipient. We aimed to determine the incidence of positive herpes virus (cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus type 1/2 (HSV-1/2), and varicella zoster virus (VZV)) PCR tests during the first year post-transplantation and assess whether a model including immune function pre-transplantation and three months post-transplantation could predict a subsequent positive herpes virus PCR.

Methods: All participants were preemptively screened for CMV, and EBV IgG-negative participants were screened for EBV during the first year post-transplantation.

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control.

The demonstration of the charge-to-spin conversion, especially with enhanced spin Hall conductivity, is crucial for the development of energy-efficient spintronic devices such as spin-orbit torque (SOT) based magnetoresistive random access memories. In this work, fully epitaxial Ru/Cu heterostructures were fabricated with interface engineering and nanolayer insertions consisting of Cu (1 nm)/Ru (1 nm) structures with different numbers of periods. The atomically controlled interface was confirmed by the high-resolution high-angle annular dark-field scanning transmission electron microscopy, and the epitaxial relationship persists even in the hybrid nanolayer insertion structures.

Weight change during the first week of life and a new method for retrospective prediction of birthweight among exclusively breastfed newborns.

Introduction: Identification of low birthweight and small for gestational age is pivotal in clinical management and many research studies, but in low-income countries, birthweight is often unavailable within 24 h of birth. Newborn weights measured within days after birth and knowledge of the growth patterns in the first week of life can help estimate the weight at birth retrospectively. This study aimed to generate sex-specific prediction maps and weight reference charts for the retrospective estimation of birthweight for exclusively breastfed newborns in a low-resource setting.

Sampling in the case-time-control design among drug users when outcome prevents further treatment.

Purpose: The objective of this article is to advocate a new way of sampling controls in the case-time-control design in a cohort of drug users when the studied outcome prevents further treatment.

Methods: Mathematically we demonstrate how a standard sampling of controls, where controls are sampled among all subjects without an event at end-of-study, leads to a biased effect estimate. We propose to add the requirement that controls initiate treatment before the calendar time of event of their matched case to circumvent this.

Bacterial and fungal bloodstream infections in solid organ transplant recipients: results from a Danish cohort with nationwide follow-up.

Objectives: Bloodstream infections (BSI) are prevalent after solid organ transplantation (SOT). In this study, we aimed to investigate the incidence and risk factors for BSI in the first 5 years post-transplantation.

Methods: The study included 1322 SOT (kidney, liver, lung and heart) recipients transplanted from 2010 to 2017 with a total of 5616 years of follow-up.

Renal function in patients with intestinal failure receiving home parenteral support.

Background: Progressive renal impairment, given by an annual decline in estimated glomerular filtration rate (eGFR), has been described in patients with intestinal failure (IF) receiving home parenteral support (HPS). The objective of this study was to examine changes in eGFR over 5 years following initiation of HPS treatment and to identify potential risk factors for loss of renal function.

Method: This retrospective database study investigates eGFR changes in nonmalignant IF patients discharged with HPS from Rigshospitalet, Copenhagen, in an 8-year period.

Radiographic Imaging to Evaluate Food Passage Rate in Preterm Piglets as a Model for Preterm Infants.

Gut motility in infants mature with increasing post-menstrual age and is affected by numerous hormonal, immunological and nutritional factors. However, it remains unclear how age and diet influence gut motility and its relation to feeding intolerance and gastric residuals in preterm neonates. Using preterm piglets as a model for infants, we investigated if contrast passage rate, as determined by X-ray contrast imaging, is affected by gestational age at birth, advancing postnatal age and different milk diets.

Testing equivalence of survival before but not after end of follow-up.

For equivalence trials with survival outcomes, a popular testing approach is the elegant test for equivalence of two survival functions suggested by Wellek (Biometrics 49: 877-881, 1993). This test evaluates whether or not the difference between the true survival curves is practically irrelevant by specifying an equivalence margin on the hazard ratio under the proportional hazards assumption. However, this approach is based on extrapolating the behavior of the survival curves to the whole time axis, whereas in practice survival times are only observed until the end of follow-up.

Examining extended human leukocyte antigen-G and HLA-F haplotypes: the HLA-G UTR-4 haplotype is associated with shorter time to pregnancy in an infertility treatment setting when both female and male partners are carriers.

Objective: To study the impact of extended human leukocyte antigen (HLA)-G and HLA-F haplotypes on time to pregnancy as measured by the number of treatment cycles in a cohort of couples in infertility treatment.

Design: Prospective cohort study of couples undergoing infertility treatment.

Setting: University hospital.

Risk of late health effects after soft-tissue sarcomas in childhood - a population-based cohort study within the Adult Life after Childhood Cancer in Scandinavia research programme.

Background: In the 1960s only 1/3 of children with soft-tissue sarcomas survived, however with improved treatments survival today has reached 70%. Given the previous poor survival and the rarity of soft-tissue sarcomas, the risk of somatic late effects in a large cohort of Nordic soft-tissue sarcoma survivors has not yet been assessed.

Methods: In this population-based cohort study we identified 985 five-year soft-tissue sarcoma survivors in Nordic nationwide cancer registries and late effects in national hospital registries covering the period 1964-2012.

S100B and brain derived neurotrophic factor in monozygotic twins with, at risk of and without affective disorders.

Background: The calcium binding protein S100B and brain derived neurotrophic factor (BDNF) are both biomarkers implicated in neuronal processes in the central nervous system and seem to be associated with affective disorders. Here we investigated both markers in a sample of monozygotic (MZ) twins with, at risk of and without affective disorders, aiming to evaluate whether these markers have a role as causal factors- or trait markers for affective disorders.

Method: We measured serum S100B and plasma BDNF levels in 204 monozygotic twins (MZ) with unipolar or bipolar disorder in remission or partial remission (affected), their unaffected co-twins (high-risk) and twins with no personal or family history of affective disorder (low-risk).

Excess cumulative incidence estimation for matched cohort survival studies.

We suggest a regression approach to estimate the excess cumulative incidence function (CIF) when matched data are available. In a competing risk setting, we define the excess risk as the difference between the CIF in the exposed group and the background CIF observed in the unexposed group. We show that the excess risk can be estimated through an extended binomial regression model that actively uses the matched structure of the data, avoiding further estimation of both the exposed and the unexposed CIFs.

Hospitalizations in Patients With Nonmalignant Short-Bowel Syndrome Receiving Home Parenteral Support.

Background: The objective of this retrospective cohort study was to assess the frequency, duration, and causes of hospitalizations in patients receiving home parenteral support (HPS) due to short-bowel syndrome (SBS) of nonmalignant causes. Furthermore, we aimed to investigate potential risk factors and hypothesized that patients with the shortest remnant, functional, small bowel-hence, the highest need for HPS-would have the highest incidence of hospitalizations.

Methods: Patients with nonmalignant SBS who initiated HPS in the period from 1970 to 2016 from the Department of Gastroenterology, Rigshospitalet, Copenhagen, Denmark, were included.

Variation in the HLA-F gene locus with functional impact is associated with pregnancy success and time-to-pregnancy after fertility treatment.

Study Question: The aim of this study was to investigate a possible influence of three single nucleotide polymorphisms (SNPs) in the HLA-F gene locus on time-to-pregnancy and pregnancy success after fertility treatment.

Summary Answer: HLA-F SNP genotypes and HLA-F diplotypes are associated with the number of fertility treatment cycles needed to achieve pregnancy and live birth.

What Is Known Already: HLA class Ib molecules, including HLA-F, which are known to be expressed by extra-villous trophoblast cells have immunomodulatory properties and play a role at the feto-maternal interface.