Selecting participants that raise a clinical trial’s population attributable fraction can increase the treatment effect within the trial and reduce the required sample size

Estimating the attributable fraction of mortality from acute respiratory distress syndrome to inform enrichment in future randomised clinical trials

BACKGROUND

Efficiency of randomised clinical trials of acute respiratory distress syndrome (ARDS) depends on the fraction of deaths attributable to ARDS (AFARDS) to which interventions are targeted. Estimates of AFARDS in subpopulations of ARDS could improve design of ARDS trials.

METHODS

We performed a matched case-control study using the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE cohort. Primary outcome was intensive care unit mortality. We used nearest neighbour propensity score matching without replacement to match ARDS to non-ARDS populations. We derived two separate AFARDS estimates by matching patients with ARDS to patients with non-acute hypoxaemic respiratory failure (non-AHRF) and to patients with AHRF with unilateral infiltrates only (AHRF-UL). We also estimated AFARDS in subgroups based on severity of hypoxaemia, number of lung quadrants involved and hyperinflammatory versus hypoinflammatory phenotypes. Additionally, we derived AFAHRF estimates by matching patients with AHRF to non-AHRF controls, and AFAHRF-UL estimates by matching patients with AHRF-UL to non-AHRF controls.

RESULTS

Estimated AFARDS was 20.9% (95% CI 10.5% to 31.4%) when compared with AHRF-UL controls and 38.0% (95% CI 34.4% to 41.6%) compared with non-AHRF controls. Within subgroups, estimates for AFARDS compared with AHRF-UL controls were highest in patients with severe hypoxaemia (41.1% (95% CI 25.2% to 57.1%)), in those with four quadrant involvement on chest radiography (28.9% (95% CI 13.4% to 44.3%)) and in the hyperinflammatory subphenotype (26.8% (95% CI 6.9% to 46.7%)). Estimated AFAHRF was 33.8% (95% CI 30.5% to 37.1%) compared with non-AHRF controls. Estimated AFAHRF-UL was 21.3% (95% CI 312.8% to 29.7%) compared with non-AHRF controls.

CONCLUSIONS

Overall AFARDS mean values were between 20.9% and 38.0%, with higher AFARDS seen with severe hypoxaemia, four quadrant involvement on chest radiography and hyperinflammatory ARDS.

Impact of metabolic disorders on endometrial receptivity in patients with polycystic ovary syndrome

The present study investigated the expression of endometrial receptivity-related molecules in patients with polycystic ovary syndrome (PCOS) and different androgen status, insulin resistance (IR) levels, and body mass indexes (BMI) to identify the mechanism underlying their effects on pregnancy outcomes. The present study recruited 43 participants from November 2020 to January 2021, which were classified into five groups: i) Hyperandrogenemia (HA) combined with impaired glucose tolerance group (n=8); ii) HA combined with diabetes mellitus group (n=8); iii) HA combined with non-IR (NIR) group (n=10); iv) non-HA (NHA) androgen combined with IR group (n=8); and v) NHA combined with NIR group (n=9). In addition, according to their BMIs, patients were sub-grouped into lean/normal (n=27), overweight (n=8) or obese (n=8) groups. The mRNA expression levels of endometrial receptivity-related molecules were detected using reverse transcription-quantitative PCR. In addition, flow cytometry was used to determine the phenotype and percentage of uterine natural killer cells (uNK). According to the results, patients with PCOS and IR status, HA and obesity (BMI ≥24 kg/m²) demonstrated significantly decreased mRNA expression levels of adiponectin, adiponectin receptor (AdipoR)1, AdipoR2, adapter protein containing PH domain, PTB domain and leucine zipper motif 1, estrogen receptor (ER) α, ERβ, progesterone receptor (PR), IL-15, integrin β3 avβ3, and insulin-like growth factor binding protein-1, but increased mRNA expression levels of IL-6 and IL-8 compared with NHA + NIR group or lean/normal group, respectively. In addition, obese patients with PCOS demonstrated increased mRNA expression levels of PR compared with overweight patients. This suggested that insulin resistant status, HA, and obesity could alter the endometrial receptivity of patients with PCOS, which may explain poorer embryo implantation and pregnancy outcomes in clinics.

Should Vitamin A Injections to Prevent Bronchopulmonary Dysplasia or Death Be Reserved for High-Risk Infants? Reanalysis of the National Institute of Child Health and Human Development Neonatal Research Network Randomized Trial

OBJECTIVE

To determine whether infants at higher risk of bronchopulmonary dysplasia (BPD) or death benefit more from vitamin A therapy than those at lower risk.

STUDY DESIGN

We conducted a post hoc reanalysis of a landmark phase III randomized controlled trial conducted from January 1996 to July 1997 at 14 university-affiliated neonatal intensive care units in the US. Data analysis was performed from October 2019 to October 2020. Infants born weighing 401-1000 g and receiving respiratory support at 24 hours of age were assigned to intramuscular vitamin A 5000 IU or sham procedure 3 times weekly for 4 weeks. The primary outcome was BPD, defined as use of supplemental oxygen, or death at 36 weeks postmenstrual age. An externally validated model for predicting BPD or death was used to estimate the risk of these outcomes for each infant.

RESULTS

As previously reported, 222 of 405 infants (54.8%) assigned vitamin A therapy and 248 of 402 infants (61.7%) in the control group developed BPD or died (relative risk [RR], 0.89 [95% CI, 0.80-0.99]; risk difference [RD], -6.9% [95% CI, -13.0 to -0.7]). The predicted individual risks of BPD or death ranged from 7.1% to 98.6% (median, 61.5%; mean, 60.9%). The effect of vitamin A therapy on BPD or death depended on infants' risk of the primary outcome (P = .03 for interaction): for example, a RR of 0.73 (RD, -14.5%) for infants with a 25% predicted risk and a RR of 0.96 (RD, -1.0%) for infants with a 75% risk. There was no difference in the decrease in vitamin A deficiency across risk groups.

CONCLUSIONS

Contrary to expectations, the effect of vitamin A therapy on BPD or death was greater for lower risk than higher risk infants.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01203488.

Efficacy of Chondroitin Sulfate in Patients with Knee Osteoarthritis: A Comprehensive Meta-Analysis Exploring Inconsistencies in Randomized, Placebo-Controlled Trials

INTRODUCTION

There are some controversies about treatment modalities in osteoarthritis (OA), including chondroitin sulfate (CS). The objective of this study was to determine whether CS is effective at alleviating pain and improving function in patients with knee OA and to identify the factors that explain inconsistencies in clinical trial results.

METHODS

We conducted a systematic review of randomized, placebo-controlled trials, searching the databases Medline, Cochrane central register for controlled trials and Scopus. Random effects meta-analysis was then performed, using tau2 and I2 statistics to assess heterogeneity. The pain and Lequesne index (LI) scores were expressed as standardized mean differences (SMDs), with a 95% confidence interval (CI). Heterogeneity was explored by stratifying the analyses according to pre-specified study-level characteristics and assessing the sources of funnel plot asymmetry.

RESULTS

The inclusion criteria yielded 18 trials. Overall, CS significantly but inconsistently reduced pain (SMD: - 0.63; 95% CI: - 0.91, - 0.35; I2 = 94%) and improved function (SMD: - 0.82; 95% CI: - 1.31, - 0.33; I2 = 95%). When limiting the analysis to studies with a low risk of bias, the pharmaceutical grade CS of IBSA origin showed a greater reduction in pain (SMD: - 0.25; 95% CI: - 0.34, - 0.16; I2 = 75%) and function (SMD: - 0.33; 95% CI: - 0.47, - 0.20; I2 = 53%, p = 0.07) compared with the other preparations (SMDPain: - 0.08; 95% CI: - 0.19, + 0.02; I2 = 20%; SMDFunction: - 0.18; 95% CI: - 0.36, +0.01; I2 = 0%). Assessing funnel plot asymmetry in the studies with a low risk of bias, we found strong correlations between the treatment effects and study size (pain: rS = 0.93; LI: rS = 0.86; p < 0.05). Ultimately, there was no residual heterogeneity in the CS effects when the smallest studies were removed from the analyses.

CONCLUSION

This new meta-analysis suggests that CS provides a moderate benefit for pain and has a large effect on function in knee OA, however with large inconsistency. The risks of bias, brand and study size were the factors explaining heterogeneity among the clinical trial results.

Personalized evidence based medicine: predictive approaches to heterogeneous treatment effects

The use of evidence from clinical trials to support decisions for individual patients is a form of "reference class forecasting": implicit predictions for an individual are made on the basis of outcomes in a reference class of "similar" patients treated with alternative therapies. Evidence based medicine has generally emphasized the broad reference class of patients qualifying for a trial. Yet patients in a trial (and in clinical practice) differ from one another in many ways that can affect the outcome of interest and the potential for benefit. The central goal of personalized medicine, in its various forms, is to narrow the reference class to yield more patient specific effect estimates to support more individualized clinical decision making. This article will review fundamental conceptual problems with the prediction of outcome risk and heterogeneity of treatment effect (HTE), as well as the limitations of conventional (one-variable-at-a-time) subgroup analysis. It will also discuss several regression based approaches to "predictive" heterogeneity of treatment effect analysis, including analyses based on "risk modeling" (such as stratifying trial populations by their risk of the primary outcome or their risk of serious treatment-related harms) and analysis based on "effect modeling" (which incorporates modifiers of relative effect). It will illustrate these approaches with clinical examples and discuss their respective strengths and vulnerabilities.

The exposure-crossover design is a new method for studying sustained changes in recurrent events

OBJECTIVES

To introduce a new design that explores how an acute exposure might lead to a sustained change in the risk of a recurrent outcome.

STUDY DESIGN AND SETTING

The exposure-crossover design uses self-matching to control within-person confounding due to genetics, personality, and all other stable patient characteristics. The design is demonstrated using population-based individual-level health data from Ontario, Canada, for three separate medical conditions (n > 100,000 for each) related to the risk of a motor vehicle crash (total outcomes, >2,000 for each).

RESULTS

The exposure-crossover design yields numerical risk estimates during the baseline interval before an intervention, the induction interval immediately ahead of the intervention, and the subsequent interval after the intervention. Accompanying graphs summarize results, provide an intuitive display to readers, and show risk comparisons (absolute and relative). Self-matching increases statistical efficiency, reduces selection bias, and yields quantitative analyses. The design has potential limitations related to confounding, artifacts, pragmatics, survivor bias, statistical models, potential misunderstandings, and serendipity.

CONCLUSION

The exposure-crossover design may help in exploring selected questions in epidemiology science.