AIPW

PURPOSE: Many studies on cancer patients investigate the impact of treatment on health-related quality of life (QoL). Typically, QoL is measured longitudinally, at baseline and at predefined timepoints thereafter. The question is whether, at a given timepoint, patients who return their questionnaire (available cases, AC) have a different QoL than those who do not return their questionnaire (non-AC). METHODS: We employed augmented inverse probability weighting (AIPW) to estimate the average QoL of non-AC in two studies on advanced-stage cancer patients...

An optimal individualized treatment regime (ITR) is a decision rule in allocating the best treatment to each patient and, hence, maximizing overall benefits. In this paper, we propose a novel framework based on nonparametric inverse probability weighting (IPW) and augmented inverse probability weighting (AIPW) estimators of the value function when the data are subject to right censoring. In contrast to most existing approaches that are designed to maximize the expected survival time under a binary treatment framework, the proposed method targets maximizing the mean residual lifetime of patients...

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AIMS: To estimate the effectiveness of metformin on glycaemic parameters among patients with incident prediabetes attending Australian general practices. METHODS: This retrospective cohort study used electronic health records of regular patients (3+ visits in two consecutive years) attending 383 Australian general practices (MedicineInsight). Patients with 'incident' prediabetes (newly recorded diagnosis between 2012 and 2017) and their glycaemic parameters (HbA1c or fasting blood glucose (FBG)) at 6-, 12-, and 18-24 months post diagnosis (unexposed) or post-management with metformin (treatment) were identified from the database...

BACKGROUND: There is mixed evidence about the impact of long-term management with hypnotic medications on blood pressure (BP). AIM: To estimate the effect of short- and long-term management with benzodiazepine and z-drugs (BZD) on BP. METHOD: Open cohort study using deidentified electronic health records of 523,486 adult regular patients (42.3% males; mean age 59.0 ± 17.0 years) annually attending 402 Australian general practices between 2016 to 2018 (MedicineInsight database)...

This article studies generalized semiparametric regression models for conditional cumulative incidence functions with competing risks data when covariates are missing by sampling design or happenstance. A doubly-robust augmented inverse probability weighted complete-case (AIPW) approach to estimation and inference is investigated. This approach modifies IPW complete-case estimating equations by exploiting the key features in the relationship between the missing covariates and the phase-one data to improve efficiency...

The main purpose of this paper is to survey the statistical inference for covariate-specific time-dependent receiver operating characteristic (ROC) curves with nonignorable missing continuous biomarker values. To construct time-dependent ROC curves, we consider a joint model which assumes that the failure time depends on the continuous biomarker and the covariates through a Cox proportional hazards model and that the continuous biomarker depends on the covariates through a semiparametric location model. Assuming a purely parametric model on the propensity score, we utilize instrumental variables to deal with the identifiable issue and estimate the unknown parameters of the propensity score by a simple and efficient method...

BACKGROUND: Psychological stress can cause various mental and physical health problems. The previous results on stress and oral health are inconsistent, possibly because of the narrow stress measurements. We aimed to examine the association between a broader range of stressful life events and oral health among workers. METHODS: This cross-sectional study analyzed anonymous individual data from a national survey in Japan. Data on stressful life events, oral health problems which are one or more of tooth pain, gum swelling/bleeding, and difficulty chewing, and covariates were obtained using a self-reported questionnaire...

INTRODUCTION: High-dose daptomycin-based combinations are recommended for vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI). Preclinical data have shown a synergistic effect of daptomycin/fosfomycin combinations against VRE. However, clinical studies comparing daptomycin monotherapy with daptomycin/fosfomycin combinations are unavailable. METHODS: An observational study of VRE-BSI was performed between 2010-2021 on patients receiving daptomycin monotherapy (≥ 8 mg/kg) or daptomycin combined with intravenous fosfomycin...

Matching-adjusted indirect comparison (MAIC) enables indirect comparisons of interventions across separate studies when individual patient-level data (IPD) are available for only one study. Due to its similarity with propensity score weighting, it has been speculated that MAIC can be combined with outcome regression models in the spirit of augmented inverse probability weighting (AIPW) estimators to improve robustness and efficiency. We show that MAIC enjoys intrinsic double-robustness and semiparametric efficiency properties for estimating the average treatment effect on the treated (ATT) in the limited IPD setting...

AIMS: Heart failure nurse practitioners (HF NP) are an emerging component of the heart failure (HF) specialist workforce but their impact in an inpatient setting is untested. The aim of this paper is to explore the impact of an inpatient HF NP service on 12 month all-cause rehospitalisations, emergency department (ED) presentations and mortality in patients hospitalised with HF compared to usual hospital care. METHODS AND RESULTS: Retrospective, 2-group comparative design involving patients (n = 408) admitted via ED with acute HF to a metropolitan quaternary hospital between January 2013 and August 2017...

BACKGROUND: The treatment options for vancomycin-resistant Enterococcus (VRE) are limited. A combination of daptomycin (DAP) and β-lactam (BL) has been suggested; however clinical studies supporting this are lacking. METHODS: Patients with VR E. faecium bacteremia who received ≥ 8 mg/kg daptomycin for ≥ 72 h and initiated ≤ 5 days of culture collection between 2010 and 2021 were included. DAP+BL was defined as receiving BL for ≥ 24 h and within 24 h of DAP initiation...

The calculation of the Augmented Inverse Probability Weighting (AIPW) estimator of the Average Treatment Effect (ATE) is carried out in two steps, where in the first step, the treatment and outcome are modeled, and in the second step, the predictions are inserted into the AIPW estimator. The model misspecification in the first step has led researchers to utilize Machine Learning algorithms instead of parametric algorithms. However, the existence of strong confounders and/or Instrumental Variables (IVs) can lead the complex ML algorithms to provide perfect predictions for the treatment model which can violate the positivity assumption and elevate the variance of AIPW estimators...

BACKGROUND: The combination of unhealthy alcohol use and depression is associated with adverse outcomes including higher rates of alcohol use disorder and poorer depression course. Therefore, addressing alcohol use among individuals with depression may have a substantial public health impact. We compared the effectiveness of a brief intervention (BI) for unhealthy alcohol use among patients with and without depression. METHOD: This observational study included 312,056 adult primary care patients at Kaiser Permanente Northern California who screened positive for unhealthy drinking between 2014 and 2017...

Commonly used semiparametric estimators of causal effects specify parametric models for the propensity score (PS) and the conditional outcome. An example is an augmented inverse probability weighting (IPW) estimator, frequently referred to as a doubly robust estimator, because it is consistent if at least one of the two models is correctly specified. However, in many observational studies, the role of the parametric models is often not to provide a representation of the data-generating process but rather to facilitate the adjustment for confounding, making the assumption of at least one true model unlikely to hold...

BACKGROUND: Intensive case management (ICM) programmes for psychotic patients are effective in improving outcomes, but often unfeasible in resource-poor settings, as they typically require extensive human resources and expertise. We developed and evaluated the effectiveness of a less intensive case management program (LICM), led by community health workers, on one-year social functioning and service use. METHODS: A prospective cohort study was conducted on patients aged 18 and above residing in a hospital catchment area...

OBJECTIVES: There is a controversy about whether both sexes' response to cardiac resynchronisation therapy (CRT) is similar. We aimed to assess a causal effect of sex on CRT response. DESIGN: Secondary analysis of a randomised controlled trial (RCT) data. Doubly robust augmented-inverse-probability-weighted (AIPW) estimation of sex effect on CRT response. SETTING: The SmartDelay Determined Atrioventricular (AV) Optimisation (SMART-AV) RCT...

OBJECTIVE: Increased visit-to-visit blood pressure variability (vvBPV) has negative effects on multiple organ systems. Prior research has suggested that dihydropyridine calcium channel blockers (CCB) may reduce vvBPV, which we attempted to verify in a high-quality dataset with robust statistical methodology. METHODS: We performed a post hoc analysis of the SPRINT trial and included participants who were on a dihydropyridine CCB either 0 or 100% of follow-up study visits...

To compare birth outcomes for patients receiving Expect With Me (EWM) group prenatal care or individual care only, we conducted a type 1 hybrid effectiveness-implementation trial (Detroit and Nashville, 2014-2016). Participants entered care <24 weeks gestation, had singleton pregnancy, and no prior preterm birth (N = 2402). Mean participant age was 27.1 (SD = 5.77); 49.5% were Black; 15.3% were Latina; 59.7% publicly insured. Average treatment effect of EWM compared to individual care only was estimated using augmented inverse probability weighting (AIPW)...

Identifying the optimal treatment decision rule, where the best treatment for an individual varies according to his/her characteristics, is of great importance when treatment effect heterogeneity exists. We develop methods for estimating the optimal treatment decision rule based on data with survival time as the primary endpoint. Our methods are based on a flexible semiparametric accelerated failure time model, where only the treatment contrast (ie, the difference in means between treatments) is parameterized and all other aspects are unspecified...