Developing and Applying the Propensity Score to Make Causal Inferences: Variable Selection and Stratification

Application of Dragonnet and Conformal Inference for Estimating Individualized Treatment Effects for Personalized Stroke Prevention: Retrospective Cohort Study

Background

Stroke is a major cause of death and disability worldwide. Identifying individuals who would benefit most from preventative interventions, such as antiplatelet therapy, is critical for personalized stroke prevention. However, traditional methods for estimating treatment effects often focus on the average effect across a population and do not account for individual variations in risk and treatment response.

Objective

This study aimed to estimate the individualized treatment effects (ITEs) for stroke prevention using a novel combination of Dragonnet, a causal neural network, and conformal inference. The study also aimed to determine and validate the causal effects of known stroke risk factors-hypertension (HT), diabetes mellitus (DM), dyslipidemia (DLP), and atrial fibrillation (AF)-using both a conventional causal model and machine learning models.

Methods

A retrospective cohort study was conducted using data from 275,247 high-risk patients treated at Ramathibodi Hospital, Thailand, between 2010 and 2020. Patients aged >18 years with HT, DM, DLP, or AF were eligible. The main outcome was ischemic or hemorrhagic stroke, identified using International Classification of Diseases, 10th Revision (ICD-10) codes. Causal effects of the risk factors were estimated using a range of methods, including: (1) propensity score-based methods, such as stratified propensity scores, inverse probability weighting, and doubly robust estimation; (2) structural causal models; (3) double machine learning; and (4) Dragonnet, a causal neural network, which was used together with weighted split-conformal quantile regression to estimate ITEs.

Results

AF, HT, and DM were identified as significant stroke risk factors. Average causal risk effect estimates for these risk factors ranged from 0.075 to 0.097 for AF, 0.017 to 0.025 for HT, and 0.006 to 0.010 for DM, depending on the method used. Dragonnet yielded causal risk ratios of 4.56 for AF, 2.44 for HT, and 1.41 for DM, which is comparable to other causal models and the standard epidemiological case-control study. Mean ITE analysis indicated that several patients with DM or DM with HT, who were not receiving antiplatelet treatment at the time of data collection, showed reductions in total risk of -0.015 and -0.016, respectively.

Conclusions

This study provides a comprehensive evaluation of stroke risk factors and demonstrates the feasibility of using Dragonnet and conformal inference to estimate ITEs of antiplatelet therapy for stroke prevention. The mean ITE analysis suggested that those with DM or DM with HT, who were not receiving antiplatelet treatment at the time of data collection, could potentially benefit from this therapy. The findings highlight the potential of these advanced techniques to inform personalized treatment strategies for stroke, enabling clinicians to identify individuals who are most likely to benefit from specific interventions.

Neurological diagnostic tests for patients with and without delirium: a prospective observational study

Since most of the precipitating factors of delirium are not due to neurological disorders, neurological diagnostic tests (NDTs) may be of limited value. We hypothesized that delirium has a high burden of NDTs with a low diagnostic yield. All patients admitted to the internal medicine wards of a single secondary teaching hospital between November 2019 and January 2020 were eligible. Within the first 48 h of their admission, they had a formal evaluation by a neuropsychologist to screen for presence of delirium. NDTs (brain MRI, brain CT, electroencephalography (EEG), and lumbar puncture) performed during the hospital stay were compared between patients with and without delirium using a logistic regression model stratified by a propensity score. The proportions of diagnostic yield (acute anomalies that changed the treatment management) provided by each type of examination were compared. Of 217 patients included, 19/32 patients (61%) with delirium had one or more NDTs, compared to 48/185 (26%) without delirium (adjusted OR 2.7; 95%CI 1.1-6.7; p = 0.027). The proportions of NDT results affecting management for patients with and without delirium were 13 and 20% for brain CT scans (p = 0.71), 29 and 38% for brain MRI (p = 0.99), and 20 and 10% for EEGs (p = 0.99), respectively. The higher proportion of NDTs performed on patients with delirium was associated with a low diagnostic yield, although not statistically different from those performed among inpatients without delirium. There is a need for restrictive, evidence-based guidelines to help with the work-up for patients with delirium.

Clinical Outcomes of 5000 IU Heparin Versus Activated Clotting Time-Guided Heparinization During Noncardiac Arterial Procedures: A Propensity Score Matched Analysis

PURPOSE

Previous studies have shown that activated clotting time (ACT)-guided heparinization leads to better anticoagulation levels during noncardiac arterial procedures (NCAP) than a standardized bolus of 5000 IU. Better anticoagulation should potentially result in lower incidence of thrombo-embolic complications (TEC). Comparative investigations on clinical outcomes of these heparinization strategies are scarce. This study investigated clinical outcomes of ACT-guided heparinization with a starting dose of 100 IU/kg in comparison with a single standardized bolus of 5000 IU heparin during NCAP.

MATERIALS AND METHODS

Analysis from a prospectively collected database of patients undergoing NCAP in 2 vascular centers was performed. Patients receiving ACT-guided heparinization were matched 1:1 with patients receiving 5000 IU heparin using propensity score matching (PSM). Primary outcomes were TEC, bleeding complications, and mortality within 30 days of procedure or during the same admission.

RESULTS

A total of 759 patients (5000 IU heparin: 213 patients, ACT-guided heparinization: 546 patients) were included. Propensity score matching resulted in 209 patients in each treatment group. After PSM, the groups were comparable, with the exception of a higher prevalence of peripheral arterial disease in the ACT-guided heparinization group (103 patients, 49% vs 82 patients, 39%, p=0.039). The target ACT (>200 seconds) was reached in 198 patients (95%) of the ACT-guided group versus 71 patients (34%) of the 5000 IU group (p<0.001), indicating successful execution of the ACT-guided protocol. Incidence of TEC (13 patients, 6.2% vs 10 patients, 4.8%, p=0.52), mortality (3 patients, 1.4% vs 0 patients, p=0.25), and bleeding complications (32 patients, 15% vs 25 patients, 12%, p=0.32) did not differ between patients receiving ACT-guided heparinization and 5000 IU heparin. Protamine was administered in 118 patients (57%) in the ACT group versus 11 patients (5.3%) in the 5000 IU group (p<0.001), but did not influence incidence of TEC (17 patients, 5.9% vs 6 patients, 4.7%, p=0.61) or bleeding complications (34 patients, 12% vs 22 patients, 17%, p=0.14).

CONCLUSION

No difference in TEC, bleeding complications, or mortality was found between ACT-guided heparinization and a single bolus of 5000 IU heparin during NCAP.

CLINICAL IMPACT

Previous studies have shown that activated clotting time (ACT)-guided heparinization leads to better anticoagulation levels during non-cardiac arterial procedures (NCAP) then a standardized bolus of 5000 IU. Comparative investigations on clinical outcomes are scarce. This study focussed on clinical outcomes of both protocols in NCAP in a propensity score matched cohort. Thrombo-embolic complications (TEC), bleeding complications and mortality within 30 days after NCAP or during the same admission were comparable between groups. Future studies should focus on optimizing ACT-guided protocols, specifically in patients with a high risk of TEC and bleeding complications.

Influence of initial misdiagnosis on mortality in patients with bacteraemia: propensity score matching and propensity score weighting analyses

BACKGROUND

The diagnostic process is a key element of medicine but it is complex and prone to errors. Infectious diseases are one of the three categories of diseases in which diagnostic errors can be most harmful to patients. In this study we aimed to estimate the effect of initial misdiagnosis of the source of infection in patients with bacteraemia on 14 day mortality using propensity score methods to adjust for confounding.

METHODS

Data from a previously described longitudinal cohort of patients diagnosed with monobacterial bloodstream infection (BSI) at the Leiden University Medical Centre (LUMC) between 2013 and 2015 were used. Propensity score matching and inversed probability of treatment weighting (IPTW) were applied to correct for confounding. The average treatment effect on the treated (ATT), which in this study was the average effect of initial misdiagnosis on the misdiagnosed (AEMM), was estimated. Methodological issues that were encountered when applying propensity score methods were addressed by performing additional sensitivity analyses. Sensitivity analyses consisted of varying caliper in propensity score matching and using different truncated weights in inversed probability of treatment weighting.

RESULTS

Data of 887 patients were included in the study. Propensity scores ranged between 0.015 and 0.999 and 80 patients (9.9%) had a propensity score > 0.95. In the matched analyses, 35 of the 171 misdiagnosed patients died within 14 days (20.5%), versus 10 of the 171 correctly diagnosed patients (5.8%), yielding a difference of 14.6% (7.6%; 21.6%). In the total group of patients, the observed percentage of patients with an incorrect initial diagnosis that died within 14 days was 19.8% while propensity score reweighting estimated that their probability of dying would have been 6.5%, if they had been correctly diagnosed (difference 13.3% (95% CI 6.9%;19.6%)). After adjustment for all variables that showed disbalance in the propensity score a difference of 13.7% (7.4%; 19.9%) was estimated. Sensitivity analyses yielded similar results. However, performing weighted analyses without truncation yielded unstable results.

CONCLUSION

Thus, we observed a substantial increase of 14 day mortality in initially misdiagnosed patients. Furthermore, several patients received propensity scores extremely close to one and were almost sure to be initially misdiagnosed.

Sphincter Pharyngoplasty for Velopharyngeal Dysfunction: Impact of 22q11.2 Deletion Syndrome

OBJECTIVE

Patients with 22q11.2 deletion syndrome (22q11DelS) often present with velopharyngeal dysfunction (VPD). VPD in patients with 22q11DelS is multifactorial beyond velopharyngeal insufficiency (VPI) alone, and differences in surgical outcomes are poorly understood. Our objective was to determine whether patients with 22q11DelS have an increased risk for persistent VPI after sphincter pharyngoplasty compared to patients without 22q11DelS.

METHODS

We completed a retrospective cohort study of patients with 22q11DelS undergoing sphincter pharyngoplasty between 1995 and 2019 using a VPD clinic database. Patients with 22q11DelS were compared to a cohort of 2:1 frequency-matched (age, degree of velopharyngeal closure) patients without 22q11DelS. Variables included patient characteristics, surgical history, perceptual speech evaluation, and degree of closure on nasopharyngoscopic evaluations. Primary outcomes included postoperative VPI severity and hypernasality. Speech and nasopharyngoscopic characteristics were compared using Fisher's exact test. Postoperative VPI severity and hypernasality were compared between groups via relative risks (RR) from mixed effects Poisson regression models, with random effects of age and velopharyngeal closure.

RESULTS

134 patients (51 22q11DelS, 83 matched) were included, with mean age of 7.3 years (standard deviation 3.0) and 50% male. Cohorts had similar preoperative speech characteristics and nasopharyngoscopic findings. Patients with 22q11DelS had similar postoperative VP function as patients without 22q11DelS (RR 0.85, CI 0.46-1.57 for VPI severity, RR 0.83, CI 0.45-1.53 for hypernasality). Even after adjusting by preoperative variables, no differences were seen between both groups.

CONCLUSION

Matched for age and pre-operative velopharyngeal closure, patients with and without 22q11DelS and VPI had similar benefits after sphincter pharyngoplasty.

LEVEL OF EVIDENCE

Non-randomized controlled cohort study, 3 Laryngoscope, 133:2813-2820, 2023.

Prophylactic Administration of Vasopressors Prior to Emergency Intubation in Critically Ill Patients: A Secondary Analysis of Two Multicenter Clinical Trials

Hypotension affects approximately 40% of critically ill patients undergoing emergency intubation and is associated with an increased risk of death. The objective of this study was to examine the association between prophylactic vasopressor administration and the incidence of peri-intubation hypotension and other clinical outcomes.

DESIGN

A secondary analysis of two multicenter randomized clinical trials. The clinical effect of prophylactic vasopressor administration was estimated using a one-to-one propensity-matched cohort of patients with and without prophylactic vasopressors.

SETTING

Seven emergency departments and 17 ICUs across the United States.

PATIENTS

One thousand seven hundred ninety-eight critically ill patients who underwent emergency intubation at the study sites between February 1, 2019, and May 24, 2021.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was peri-intubation hypotension defined as a systolic blood pressure less than 90 mm Hg occurring between induction and 2 minutes after tracheal intubation. A total of 187 patients (10%) received prophylactic vasopressors prior to intubation. Compared with patients who did not receive prophylactic vasopressors, those who did were older, had higher Acute Physiology and Chronic Health Evaluation II scores, were more likely to have a diagnosis of sepsis, had lower pre-induction systolic blood pressures, and were more likely to be on continuous vasopressor infusions prior to intubation. In our propensity-matched cohort, prophylactic vasopressor administration was not associated with reduced risk of peri-intubation hypotension (41% vs 32%; p = 0.08) or change in systolic blood pressure from baseline (-12 vs -11 mm Hg; p = 0.66).

CONCLUSIONS

The administration of prophylactic vasopressors was not associated with a lower incidence of peri-intubation hypotension in our propensity-matched analysis. To address potential residual confounding, randomized clinical trials should examine the effect of prophylactic vasopressor administration on peri-intubation outcomes.

Propensity Scores: Confounder Adjustment When Comparing Nonrandomized Groups in Orthopaedic Surgery

Many studies in arthroplasty research are based on nonrandomized, retrospective, registry-based cohorts. In these types of studies, patients belonging to different treatment or exposure groups often differ with respect to patient characteristics, medical histories, surgical indications, or other factors. Consequently, comparisons of nonrandomized groups are often subject to treatment selection bias and confounding. Propensity scores can be used to balance cohort characteristics, thus helping to minimize potential bias and confounding. This article explains how propensity scores are created and describes multiple ways in which they can be applied in the analysis of nonrandomized studies. Please visit the following (https://www.youtube.com/watch?v=sqgxl_nZWS4&t=3s) for a video that explains the highlights of the paper in practical terms.

Dealing with confounding in observational studies: A scoping review of methods evaluated in simulation studies with single-point exposure

The aim of this article was to perform a scoping review of methods available for dealing with confounding when analyzing the effect of health care treatments with single-point exposure in observational data. We aim to provide an overview of methods and their performance assessed by simulation studies indexed in PubMed. We searched PubMed for simulation studies published until January 2021. Our search was restricted to studies evaluating binary treatments and binary and/or continuous outcomes. Information was extracted on the methods' assumptions, performance, and technical properties. Of 28,548 identified references, 127 studies were eligible for inclusion. Of them, 84 assessed 14 different methods (ie, groups of estimators that share assumptions and implementation) for dealing with measured confounding, and 43 assessed 10 different methods for dealing with unmeasured confounding. Results suggest that there are large differences in performance between methods and that the performance of a specific method is highly dependent on the estimator. Furthermore, the methods' assumptions regarding the specific data features also substantially influence the methods' performance. Finally, the methods result in different estimands (ie, target of inference), which can even vary within methods. In conclusion, when choosing a method to adjust for measured or unmeasured confounding it is important to choose the most appropriate estimand, while considering the population of interest, data structure, and whether the plausibility of the methods' required assumptions hold.

Disruptiveness of COVID-19: Differences in Course Engagement, Self-Appraisal, and Learning

We investigated how the transition to remote instruction during the COVID-19 pandemic affected students' engagement, self-appraisals, and learning in advanced placement (AP) Statistics courses. Participants included 681 (Mage=16.7 years, SDage=.90; %female=55.4) students enrolled in the course during 2017-2018 (N=266), 2018-2019 (N=200), and the pandemic-affected 2019-2020 (N=215) school years. Students enrolled during the pandemic-affected year reported a greater improvement in affective engagement but a decrease in cognitive engagement in the spring semester relative to a previous year. Females enrolled in the pandemic-affected year experienced a greater negative change in affective and behavioral engagement. Students enrolled during the pandemic-affected year reported a greater decrease in their anticipated AP exam scores and received lower scores on a practice exam aligned with the AP exam compared to a prior year. Although students were resilient in some respects, their self-appraisal and learning appear to have been negatively affected by pandemic circumstances.

Target Trial Emulation: A Design Tool for Cancer Clinical Trials

PURPOSE

To apply target trial emulation to explore the potential impact of eligibility criteria on the primary outcome of a randomized controlled trial.

METHODS

Simulations of a real-world explanatory trial of transarterial radioembolization for advanced unresectable hepatocellular carcinoma with portal vein invasion were performed to examine the effects of cohort specification on survival outcomes and patient sample size. Simulations comprised 24 different permutations of the trial varied on three disease nonspecific eligibility parameters. Treatment and control arms for these emulated trials were drawn from the National Cancer Database and matched by treatment propensity. Target trial emulation served as the causal framework for this analysis, allowing the architecture of a true controlled experiment to address forms of bias routinely encountered in comparative effectiveness studies involving real-world observational data.

RESULTS

Twenty-four propensity score-matched cohorts comprising a wider clinical spectrum of patients than specified by the original target trial were successfully generated using the National Cancer Database. The arms for each of the emulated trials demonstrated exchangeability across all eligibility criteria and other clinical covariates. Significant treatment benefits were associated with only a narrow range of eligibility criteria, indicating that the original target trial was well specified.

CONCLUSION

The impact of patient selection on treatment outcomes can be studied using target trial emulation. This analytical framework can furthermore serve to leverage existing real-world data to inform the task of cohort specification for a randomized controlled trial, facilitating a more data-driven approach for this important step in clinical trial design.

Cost comparison between spinal versus general anesthesia for hip and knee arthroplasty: an incremental cost study

PURPOSE

Wait list times for total joint arthroplasties have been growing, particularly in the aftermath of the COVID-19 pandemic. Increasing operating room (OR) efficiency by reducing OR time and associated costs while maintaining quality allows the greatest number of patients to receive care.

METHODS

We used propensity score matching to compare parallel processing with spinal anesthesia in a block room vs general anesthesia in a retrospective cohort of adult patients undergoing primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). We compared perioperative costs, hospital costs, OR time intervals, and complications between the groups with nonparametric tests using an intention-to-treat approach.

RESULTS

After matching, we included 636 patients (315 TKA; 321 THA). Median [interquartile range (IQR)] perioperative costs were CAD 7,417 [6,521-8,109], and hospital costs were CAD 10,293 [9,344-11,304]. Perioperative costs were not significantly different between groups (pseudo-median difference [MD], CAD -47 (95% confidence interval [CI], -214 to -130; P = 0.60); nor were total hospital costs (MD, CAD -78; 95% CI, -340 to 178; P = 0.57). Anesthesia-controlled time and total intraoperative time were significantly shorter for spinal anesthesia (MD, 14.6 min; 95% CI, 13.4 to 15.9; P < 0.001; MD, 15.9; 95% CI, 11.0 to 20.9; P < 0.001, respectively). There were no significant differences in complications.

CONCLUSION

Spinal anesthesia in the context of a dedicated block room reduced both anesthesia-controlled time and total OR time. This did not translate into a reduction in incremental cost in the spinal anesthesia group.

[Do Others Care about me and Encourage me to be Myself? A Propensity-Score Analysis on the Effect of Chronic Health Impairments on Work-Related Perceived Inclusion]

PURPOSE

Our study evaluated the effect of chronic health impairments on work-related perceived inclusion.

METHODS

Using an online questionnaire, we collected data on employees' perceived inclusion (1807 with and 540 without impairments) and identified matched pairs based on propensity scores.

RESULTS

Employees with impairments perceived themselves as less included than their matched pairs without impairments, but only if they regarded themselves as severely limited in their work activities or if they regarded their impairment as severely stigmatized. Limitations and stigmata were found to be independent negative predictors of perceived inclusion.

CONCLUSION

Our findings suggest a need for measures to improve the work-related perceived inclusion of people with chronic health impairments. Such measures should aim at optimising workplace accommodations as well as changing performance-related social norms in organisations and stereotypical assumptions about employees with chronic health impairments.

PTSD treatment reduces risk of trauma recidivism in a diverse community at a safety-net hospital: A propensity score analysis of data from a level one trauma center

BACKGROUND

Physically-traumatic injuries result in PTSD for approximately 10% of Americans, and this rate is higher among individuals of color and those living in poverty. Individuals of color living in poverty experience lower access to PTSD and other mental health services. Untreated PTSD is associated with increased risk of trauma recidivism, but it is unknown if provision of treatment is actually associated with a subsequent reduction in recidivism risk.

METHODS

For this observational cross-sectional study, data were collected retrospectively from the Trauma Registry of a level one trauma center, safety-net hospital in New Orleans between 2018 and 2020. Receipt of outpatient PTSD treatment at this same hospital was evaluated via chart review of the electronic health record. Propensity score matching was used to balance confounding variables of trauma type (assault vs. non-assault), gender, and race. McNemar test and Cox proportional hazard model were used with the propensity-balanced dataset to assess differences in trauma recidivism according to PTSD treatment status.

RESULTS

Among 5916 trauma activations that occurred in the study period, 92 instances of recidivism occurred. 91 pairs were established after balancing with the propensity score. 1-year recidivism was 2.2% (n = 2) of all treated individuals versus 15.4% (n = 14) of non-treated individuals (p < 0.0001). The marginal risk from the Cox proportional hazard model demonstrated an 82% reduction in risk of recidivism (p = 0.02).

CONCLUSIONS

This study demonstrated that mental health treatment can be used to reduce trauma recidivism. These data were shown among a high-risk population of disproportionately Black men living in a low-income community. Ensuring access to quality mental health care is one way to address the health disparities associated with physically-traumatic injuries.

Research and scholarly methods: Propensity scores

Propensity score methods are increasingly used as a tool to control for confounding bias in pharmacoepidemiologic studies. The propensity score is a dimension reducing balancing score, creating treatment and reference groups that have comparable distributions of measured covariates. The purpose of this methods review is to provide an overview of the use of propensity score methods, including a summary of important data assumptions, various applications of the propensity score, and how to evaluate covariate balance. This article is intended for pharmacists and researchers who wish to receive an introduction to propensity score methods and be able to engage in high-level discussions on application and reporting.

Best Practice Guidelines for Propensity Score Methods in Medical Research: Consideration on Theory, Implementation, and Reporting. A Review

Rigorous and reproducible methodology of controlling for bias is essential for high-quality, evidence-based studies. Propensity score matching (PSM) is a valuable way to control for bias and achieve pseudo-randomization in retrospective observation studies. The purpose of this review is to 1) provide a clear conceptual framework for PSM, 2) recommend how to best report its use in studies, and 3) offer some practical examples of implementation. First, this article covers the concepts behind PSM, discusses its pros and cons, and compares it with other methods of controlling for bias, namely, hard/exact matching and regression analysis. Second, recommendations are given for what to report in a manuscript when PSM is used. Finally, a worked example is provided, which can also serve as a template for the reader's own studies. A study's conclusions are only as strong as its methods. PSM is an invaluable tool for producing rigorous and reproducible results in observational studies. The goal of this article is to give practicing clinical physicians not only a better understanding of PSM and its implications but the ability to implement it for their own studies. STUDY DESIGN: Review.

Comparative Safety and Effectiveness of Vedolizumab to Tumor Necrosis Factor Antagonist Therapy for Ulcerative Colitis

BACKGROUND & AIMS

We aimed to compare safety and effectiveness of vedolizumab to tumor necrosis factor (TNF)-antagonist therapy in ulcerative colitis in routine practice.

METHODS

A multicenter, retrospective, observational cohort study (May 2014 to December 2017) of ulcerative colitis patients treated with vedolizumab or TNF-antagonist therapy. Propensity score weighted comparisons for development of serious adverse events and achievement of clinical remission, steroid-free clinical remission, and steroid-free deep remission. A priori determined subgroup comparisons in TNF-antagonist-naïve and -exposed patients, and for vedolizumab against infliximab and subcutaneous TNF-antagonists separately.

RESULTS

A total of 722 (454 vedolizumab, 268 TNF antagonist) patients were included. Vedolizumab-treated patients were more likely to achieve clinical remission (hazard ratio [HR], 1.651; 95% confidence interval [CI], 1.229-2.217), steroid-free clinical remission (HR, 1.828; 95% CI, 1.135-2.944), and steroid-free deep remission (HR, 2.819; 95% CI, 1.496-5.310) than those treated with TNF antagonists. Results were consistent across subgroup analyses in TNF-antagonist-naïve and -exposed patients, and for vedolizumab vs infliximab and vs subcutaneous TNF-antagonist agents separately. Overall, there were no statistically significant differences in the risk of serious adverse events (HR, 0.899; 95% CI, 0.502-1.612) or serious infections (HR, 1.235; 95% CI, 0.608-2.511) between vedolizumab-treated and TNF-antagonist-treated patients. However, in TNF-antagonist-naïve patients, vedolizumab was less likely to be associated with serious adverse events than TNF antagonists (HR, 0.192; 95% CI, 0.049-0.754).

CONCLUSIONS

Treatment of ulcerative colitis with vedolizumab is associated with higher rates of remission than treatment with TNF-antagonist therapy in routine practice, and lower rates of serious adverse events in TNF-antagonist-naïve patients.

Conditional cash transfers and adolescent mental health in Brazil: Evidence from the 2004 Pelotas Birth Cohort

BACKGROUND

Young people living in poverty are at higher risk of mental disorders, but whether interventions aimed to reduce poverty have lasting effects on mental health has not been well established. We examined whether exposure to Brazil's conditional cash transfers programme (CCT), Bolsa Família (BFP), during childhood reduces the risk of mental health problems in early adolescence.

METHODS

We used data from 2063 participants in the 2004 Pelotas Birth Cohort study. Propensity score matching (PSM) estimated the association between BFP participation at age 6 and externalising problems (Strengths and Difficulties Questionnaire - SDQ and violent behaviour) and socio-emotional competencies (Development and Well-Being Assessment questionnaire, and the Nowick-Strickland Internal-External Scale) at age 11.

RESULTS

PSM results suggest that programme participation at age of six was not significantly associated with externalising problems (P = 0.433), prosocial behaviour (P = 0.654), violent behaviour (P = 0.342), social aptitudes (P = 0.281), positive attributes (P = 0.439), or locus of control (P = 0.148) at the age of 11 years.

CONCLUSIONS

Participation in BFP during childhood was not associated with improved or worsened mental health in early adolescence. While we cannot fully discard that findings may be due to adverse selection, results suggest that CCTs alone may not be sufficient to improve mental health outcomes and would be prudent to assess whether mental health interventions as an addition to CCTs may be helpful.

Comparing Propensity Score Methods Versus Traditional Regression Analysis for the Evaluation of Observational Data: A Case Study Evaluating the Treatment of Gram-Negative Bloodstream Infections

BACKGROUND

Propensity score methods are increasingly being used in the infectious diseases literature to estimate causal effects from observational data. However, there remains a general gap in understanding among clinicians on how to critically review observational studies that have incorporated these analytic techniques.

METHODS

Using a cohort of 4967 unique patients with Enterobacterales bloodstream infections, we sought to answer the question "Does transitioning patients with gram-negative bloodstream infections from intravenous to oral therapy impact 30-day mortality?" We conducted separate analyses using traditional multivariable logistic regression, propensity score matching, propensity score inverse probability of treatment weighting, and propensity score stratification using this clinical question as a case study to guide the reader through (1) the pros and cons of each approach, (2) the general steps of each approach, and (3) the interpretation of the results of each approach.

RESULTS

2161 patients met eligibility criteria with 876 (41%) transitioned to oral therapy while 1285 (59%) remained on intravenous therapy. After repeating the analysis using the 4 aforementioned methods, we found that the odds ratios were broadly similar, ranging from 0.84-0.95. However, there were some relevant differences between the interpretations of the findings of each approach.

CONCLUSIONS

Propensity score analysis is overall a more favorable approach than traditional regression analysis when estimating causal effects using observational data. However, as with all analytic methods using observational data, residual confounding will remain; only variables that are measured can be accounted for. Moreover, propensity score analysis does not compensate for poor study design or questionable data accuracy.

Comparative safety and effectiveness of vedolizumab to tumour necrosis factor antagonist therapy for Crohn's disease

BACKGROUND

Direct comparisons are lacking between vedolizumab and tumour necrosis factor (TNF)-antagonist therapy in Crohn's disease (CD).

AIM

To compare safety and effectiveness of vedolizumab and TNF-antagonist therapy in adult CD patients.

METHODS

Retrospective observational cohort (May 2014-December 2017) propensity score-weighted comparison of vedolizumab vs TNF-antagonist therapy (infliximab, adalimumab, certolizumab) in CD. Propensity scores were weighted for age, prior treatments, disease complications, extent and severity, steroid dependence, and concomitant immunosuppressive drug use. The primary outcome was comparative risk for infections or non-infectious serious adverse events (requiring antibiotics, antivirals, antifungals, hospitalisation, or treatment discontinuation, or resulting in death). Secondary comparative effectiveness outcomes were clinical remission (resolution of CD-related symptoms), steroid-free clinical remission and endoscopic remission (absence of ulcers/erosions).

RESULTS

We included 1266 patients (n = 659 vedolizumab). Rates of non-infectious serious adverse events (odds ratio [OR] 0.072, 95% confidence interval [CI] 0.012-0.242), but not serious infections (OR 1.183, 95% CI 0.786-1.795), were significantly lower with vedolizumab vs TNF-antagonist therapy. Safety comparisons for non-infectious serious adverse events remained significant after adjusting for differences in duration of exposure. No significant difference was observed between vedolizumab and TNF-antagonist therapy for clinical remission (hazard ratio [HR] 0.932, 95% CI 0.707-1.228), steroid-free clinical remission (HR 1.250, 95% CI 0.677-2.310) or endoscopic remission (HR 0.827, 95% CI 0.595-1.151). TNF-antagonist therapy was associated with higher treatment persistence compared with vedolizumab.

CONCLUSIONS

There was a lower risk of non-infectious serious adverse events, but not serious infections, with vedolizumab vs TNF-antagonist therapy, with no significant difference for achieving disease remission.

Impact of Transport Time and Cardiac Arrest Centers on the Neurological Outcome After Out-of-Hospital Cardiac Arrest: A Retrospective Cohort Study

Background

Should all out‐of‐hospital cardiac arrest (OHCA) patients be directly transported to cardiac arrest centers (CACs) remains under debate. Our study evaluated the impacts of different transport time and destination hospital on the outcomes of OHCA patients.

Methods and Results

Data were collected from 6655 OHCA patients recorded in the regional prospective OHCA registry database of Taoyuan City, Taiwan, between January 2012 and December 2016. Patients were matched on propensity score, which left 5156 patients, 2578 each in the CAC and non‐CAC groups. Transport time was dichotomized into <8 and ≥8 minutes. The relations between the transport time to CACs and good neurological outcome at discharge and survival to discharge were investigated. Of the 5156 patients, 4215 (81.7%) presented with nonshockable rhythms and 941 (18.3%) presented with shockable rhythms. Regardless of transport time, transportation to a CAC increased the likelihoods of survival to discharge (<8 minutes: adjusted odds ratio [aOR], 1.95; 95% CI, 1.11–3.41; ≥8 minutes: aOR, 1.92; 95% CI, 1.25–2.94) and good neurological outcome at discharge (<8 minutes: aOR, 2.70; 95% CI, 1.40–5.22; ≥8 minutes: aOR, 2.20; 95% CI, 1.29–3.75) in OHCA patients with shockable rhythms but not in patients with nonshockable rhythms.

Conclusions

OHCA patients with shockable rhythms transported to CACs demonstrated higher probabilities of survival to discharge and a good neurological outcome at discharge. Direct ambulance delivery to CACs should thus be considered, particularly when OHCA patients present with shockable rhythms.

Arts for ageing well: a propensity score matching analysis of the effects of arts engagements on holistic well-being among older Asian adults above 50 years of age

OBJECTIVE

To assess the frequency and intensity of arts engagement inclusive of active and passive engagements in arts, culture and heritage activities among Singaporean adults aged 50 and above, and examine the relationships between participatory art and holistic well-being.

DESIGN

Cross-sectional stratified household survey.

SETTING

All residential areas across Singapore's Central, East, North, North-East and West Regions.

PARTICIPANTS

1067 community-dwelling, Singaporean older adults between the ages of 50 and 95 years were recruited.

PRIMARY AND SECONDARY OUTCOME MEASURES

Respondents completed a self-reported questionnaire, consisting of standardised ad hoc items assessing the frequencies and durations of active and passive participatory arts engagement, as well as validated psychometric assessments on psychosociospiritual health including the primary outcome measure on quality of life, and the secondary outcome measures on physical, psychological, emotional, spiritual, and social well-being. sociodemographic information, as well as frequency and intensity of physical activity were also collected.

RESULTS

Passive engagement (60%) and active engagement (17%) in the arts were associated with better holistic wellness and social support. Specifically, findings from the propensity score matching and independent t-test analyses revealed that adults aged 50 and above who passively engaged in arts and culture-related events experienced higher quality of life (t(728)=3.35, p=0.0008, d=0.25), perceived health (t(728)=2.21, p=0.0277, d=0.16) and sense of belonging (t(728)=2.17, p=0.03, d=0.16), as compared with those who did not. Moreover, those who actively engaged in participatory arts experienced greater quality of life (t(442)=3.68, p=0.0003, d=0.36), self-rated health (t(442)=2.59, p=0.0099, d=0.25), spiritual well-being (t(442)=3.75, p=0.0002, d=0.37), meaning in life (t(442)=5.03, p<0.0001, d=0.50) and sense of peace (t(442)=3.72, p=0.0002, d=0.36), as compared with those who did not actively engaged in the arts.

CONCLUSION

This study provided robust evidence to support a significant causal relationship between arts engagements and holistic well-being. Recommendations for art-based public health and elderly care research, practice and policy are discussed.

Propensity Score Methods in Health Technology Assessment: Principles, Extended Applications, and Recent Advances

Randomized clinical trials (RCT) are accepted as the gold-standard approaches to measure effects of intervention or treatment on outcomes. They are also the designs of choice for health technology assessment (HTA). Randomization ensures comparability, in both measured and unmeasured pretreatment characteristics, of individuals assigned to treatment and control or comparator. However, even adequately powered RCTs are not always feasible for several reasons such as cost, time, practical and ethical constraints, and limited generalizability. RCTs rely on data collected on selected, homogeneous population under highly controlled conditions; hence, they provide evidence on efficacy of interventions rather than on effectiveness. Alternatively, observational studies can provide evidence on the relative effectiveness or safety of a health technology compared to one or more alternatives when provided under the setting of routine health care practice. In observational studies, however, treatment assignment is a non-random process based on an individual’s baseline characteristics; hence, treatment groups may not be comparable in their pretreatment characteristics. As a result, direct comparison of outcomes between treatment groups might lead to biased estimate of the treatment effect. Propensity score approaches have been used to achieve balance or comparability of treatment groups in terms of their measured pretreatment covariates thereby controlling for confounding bias in estimating treatment effects. Despite the popularity of propensity scores methods and recent important methodological advances, misunderstandings on their applications and limitations are all too common. In this article, we present a review of the propensity scores methods, extended applications, recent advances, and their strengths and limitations.