Publications by authors named "Alexander Levis"

Missing data arise in most applied settings and are ubiquitous in electronic health records (EHR). When data are missing not at random (MNAR) with respect to measured covariates, sensitivity analyses are often considered. These solutions, however, are often unsatisfying in that they are not guaranteed to yield actionable conclusions.

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Article Synopsis
  • The study investigates how using small datasets to select an optimal cutoff score for the Patient Health Questionnaire-9 (PHQ-9) can lead to inaccurate results.
  • Researchers evaluated whether data-driven methods for cutoff selection resulted in scores that were significantly different from the true population optimal score and if these methods produced biased accuracy estimates.
  • Findings showed that many small studies frequently failed to identify the correct optimal cutoff score, particularly in smaller samples, leading to an overestimation of test sensitivity.
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Recent years have experienced increasing utilization of complex machine learning models across multiple sources of data to inform more generalizable decision-making. However, distribution shifts across data sources and privacy concerns related to sharing individual-level data, coupled with a lack of uncertainty quantification from machine learning predictions, make it challenging to achieve valid inferences in multi-source environments. In this paper, we consider the problem of obtaining distribution-free prediction intervals for a target population, leveraging multiple potentially biased data sources.

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Optogenetics is a powerful neuroscience technique for studying how neural circuit manipulation affects behavior. Standard analysis conventions discard information and severely limit the scope of the causal questions that can be probed. To address this gap, we 1) draw connections to the causal inference literature on sequentially randomized experiments, 2) propose a non-parametric framework for analyzing "open-loop" (static regime) optogenetics behavioral experiments, 3) derive extensions of history-restricted marginal structural models for dynamic treatment regimes with positivity violations for "closed-loop" designs, and 4) propose a taxonomy of identifiable causal effects that encompass a far richer collection of scientific questions compared to standard methods.

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Article Synopsis
  • Billions globally face micronutrient deficiencies, with Madagascar being particularly vulnerable—nearly half the population is stunted, and some areas are in emergency conditions similar to famine.
  • Research from 2013-2020 involved 4,710 individuals, revealing alarming deficiency rates: 66.5% for zinc, 15.6% for vitamin B, and 11.6% for retinol, along with notable iron deficiencies.
  • The study also found high levels of inflammation in the population, with 24% experiencing chronic inflammation and significant geographic variations in nutrient deficiencies, indicating that some regions are much worse off than others.
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Background: Systemic sclerosis (scleroderma; SSc) is a rare autoimmune connective tissue disease. Functional impairment of hands is common. The Scleroderma Patient-centered Intervention Network (SPIN)-HAND trial compared effects of offering access to an online self-guided hand exercise program to usual care on hand function (primary) and functional health outcomes (secondary) in people with SSc with at least mild hand function limitations.

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Background: More people with rare diseases likely receive disease education and emotional and practical support from peer-led support groups than any other way. Most rare-disease support groups are delivered outside of the health care system by untrained leaders. Potential benefits may not be achieved and harms, such as dissemination of inaccurate information, may occur.

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Background: Systemic sclerosis (scleroderma; SSc) is a rare autoimmune connective tissue disease. We completed an initial feasibility trial of an online self-administered version of the Scleroderma Patient-centered Intervention Network Self-Management (SPIN-SELF) Program using the cohort multiple randomized controlled trial (RCT) design. Due to low intervention offer uptake, we will conduct a new feasibility trial with progression to full-scale trial, using a two-arm parallel, partially nested RCT design.

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Background: To determine the impact of an intensive perioperative nutritional and lifestyle support protocol on long-term outcomes of bariatric surgery.

Methods: A retrospective observational study was conducted of 955 patients who underwent gastric bypass surgery between 2005 and 2015. Patients were divided into two cohorts: (1) 2005 through August 2013: these 767 patients were required to participate in the intensive telephone-based nutritional support program from 8 weeks preoperative through 44 weeks postoperative; (2) after August 2013, the program was discontinued and 188 patients did not have intensive telephonic nutritional support.

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Background: Expansion of access to surgical care can improve health outcomes, although the impact that scale-up of the surgical workforce will have on child mortality is poorly defined. In this study, we estimate the number of child deaths potentially avertable by increasing the surgical workforce globally to meet targets proposed by the Lancet Commission on Global Surgery.

Methods: To estimate the number of deaths potentially avertable through increases in the surgical workforce, we used log-linear regression to model the association between surgeon, anesthetist and obstetrician workforce (SAO) density and surgically amenable under-5 mortality rate (U5MR), infant mortality rate (IMR), and neonatal mortality rate (NMR) for 192 countries adjusting for potential confounders of childhood mortality, including the non-surgical workforce (physicians, nurses/midwives, community health workers), gross national income per capita, poverty rate, female literacy rate, health expenditure per capita, percentage of urban population, number of surgical operations, and hospital bed density.

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Background: No trials have tested multifaceted mental health interventions recommended by public health organisations during COVID-19. The objective of this trial was to evaluate the effect of the Scleroderma Patient-centered Intervention Network COVID-19 Home-isolation Activities Together (SPIN-CHAT) Program on anxiety symptoms and other mental health outcomes among people vulnerable during COVID-19 owing to a pre-existing medical condition.

Methods: The SPIN-CHAT Trial was a pragmatic, two-arm, parallel, partially nested, randomised, controlled trial (1:1 allocation to intervention or waitlist).

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Purpose: Missing data is common in electronic health records (EHR)-based obesity research. To avoid bias, it is critical to understand mechanisms that underpin missingness. We conducted a survey among bariatric surgery patients in three integrated health systems to (i) investigate predictors of disenrollment and (ii) examine differences in weight between disenrollees and enrollees at 5 years.

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Aims: This study used a large database to develop a reliable and valid shortened form of the Edinburgh Postnatal Depression Scale (EPDS), a self-report questionnaire used for depression screening in pregnancy and postpartum, based on objective criteria.

Methods: Item responses from the 10-item EPDS were obtained from 5157 participants (765 major depression cases) from 22 primary screening accuracy studies that compared the EPDS to the Structured Clinical Interview for DSM (SCID). Unidimensionality of the EPDS latent construct was verified using confirmatory factor analysis, and an item response theory model was fit.

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Objective: We evaluated whether sample size differences between arms of two-arm parallel group randomized controlled trials (RCTs) published in American Psychological Association (APA)-affiliated journals were consistently smaller than expected by chance with simple randomization.

Method: We searched PsycINFO for two-arm parallel group RCTs in APA-affiliated journals published January 2007 to September 2017 that used individual randomization (1:1 allocation ratio), reported the number of participants randomized, and did not describe employing restrictive randomization (e.g.

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Background: Little is known about the benefits, and barriers and facilitators to providing psychosocial support to caregivers to a loved one with a rare disease.

Objective: The aim of our scoping review was to map evidence on (1) perceived benefits and (2) barriers and facilitators of establishing and maintaining services.

Methods: The CINAHL and PubMed databases were searched in December 2018.

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Article Synopsis
  • - The PHQ-9 is a 9-question tool for identifying and assessing the severity of depression, while the shorter PHQ-2 focuses on the frequency of depressed mood and anhedonia and can serve as an initial screening step.
  • - A study combining data from various sources aimed to evaluate the accuracy of the PHQ-2 alone and alongside the PHQ-9 in detecting major depression through comparisons with validated diagnostic interviews.
  • - Results showed that the PHQ-2 has good sensitivity (91%) but lower specificity (67%) at a score cutoff of 2, with improved performance at a cutoff of 3, indicating it can effectively help in initial screenings for depression when used with interviews.
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Objectives: We evaluated whether sample sizes in different arms of two-arm parallel group randomized controlled trials of nonregulated interventions were systematically closer in size than would plausibly occur by chance if simple randomization had been applied.

Study Design And Setting: We searched PubMed for trials of nonregulated health care interventions that did not report using restricted randomization from journals in behavioral sciences and psychology, nursing, nutrition and dietetics, rehabilitation, and surgery. We emailed trial authors to clarify randomization procedures.

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Background: Screening for major depression with the Patient Health Questionnaire-9 (PHQ-9) can be done using a cutoff or the PHQ-9 diagnostic algorithm. Many primary studies publish results for only one approach, and previous meta-analyses of the algorithm approach included only a subset of primary studies that collected data and could have published results.

Objective: To use an individual participant data meta-analysis to evaluate the accuracy of two PHQ-9 diagnostic algorithms for detecting major depression and compare accuracy between the algorithms and the standard PHQ-9 cutoff score of ≥10.

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Importance: Many interventions that are important to the health care of patients are not subject to regulation by the US Food and Drug Administration (FDA) or comparable regulatory bodies in other nations.

Objective: To determine whether specialty journals that publish trials of primarily nonregulated health care interventions require prospective registration and whether the prospective registration policies are associated with the publication of prospectively registered trials, trials with adequately registered outcomes, and trials with primary outcomes consistent with the registered primary outcomes.

Design And Methods: PubMed was searched daily, from March 18, 2016, to September 17, 2016, for nonregulated intervention randomized clinical trials.

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Background: The objective of this study was to develop and validate a short form of the Patient Health Questionnaire-9 (PHQ-9), a self-report questionnaire for assessing depressive symptomatology, using objective criteria.

Methods: Responses on the PHQ-9 were obtained from 7,850 English-speaking participants enrolled in 20 primary diagnostic test accuracy studies. PHQ unidimensionality was verified using confirmatory factor analysis, and an item response theory model was fit.

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Background: Different diagnostic interviews are used as reference standards for major depression classification in research. Semi-structured interviews involve clinical judgement, whereas fully structured interviews are completely scripted. The Mini International Neuropsychiatric Interview (MINI), a brief fully structured interview, is also sometimes used.

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In studies of diagnostic test accuracy, authors sometimes report results only for a range of cutoff points around data-driven "optimal" cutoffs. We assessed selective cutoff reporting in studies of the diagnostic accuracy of the Patient Health Questionnaire-9 (PHQ-9) depression screening tool. We compared conventional meta-analysis of published results only with individual-patient-data meta-analysis of results derived from all cutoff points, using data from 13 of 16 studies published during 2004-2009 that were included in a published conventional meta-analysis.

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