Observational studies using propensity score analysis underestimated the effect sizes in critical care medicine

Protective and risk factors of anxiety in children and adolescents during COVID-19: A systematic review and three level meta-analysis

BACKGROUND

In order to gain a deepened understanding of the impact of public health emergency and to develop effective interventions and preventions, this study aimed to evaluate risk and protective factors associated with anxiety in children and adolescents and to explore potential moderators in the background of COVID-19 within the framework of socio-ecological model.

METHODS

A literature search was conducted in Web of Science, MEDLINE, PubMed, Scopus, EBSCO, ScienceDirect, Emerald, and CNKI for studies published from early 2020 to early 2023 that examined factors associated with anxiety among children and adolescents with age range of 6 to 17 years old. Random effects models and a three-level meta-analytic approach were used.

RESULTS

In total, 141 articles and 1,018,171 subjects were included, with 1002 effect sizes extracted. 32 protective factors and 48 risk factors were examined, yielding significance for 14 protective factors and 29 risk factors, including individual factors (e.g., gender, logOR = -0.37, 95 % CI [-0.47, -0.27], p < 0.001; age, logOR = -0.12, 95 % CI [-0.22, -0.02], p = 0.02; emotional functioning, logOR = -1.45, 95 % CI [-1.84, -1.05], p < 0.001; pre-existing condition logOR = 0.94, 95 % CI [0.58, 1.30], p < 0.001; electronic device or internet addiction, logOR = 1.81, 95 % CI [0.74, 2.88], p < 0.001), family factors (e.g., family socioeconomic status, logOR = -0.25, 95 % CI [-0.39, -0.10], p < 0.001; family functioning, logOR = -1.31, 95 % CI [-1.60, -1.02], p < 0.001; anxiety level of caregiver, logOR = 1.06, 95 % CI [0.75, 1.37], p < 0.001), community factors (e.g., overall social support, logOR = -0.93, 95 % CI [-1.84, -1.05], p < 0.001; school burden, logOR = 0.56, 95 % CI [0.21, 0.90], p = 0.002), and COVID-19-related factors (e.g., higher exposure risk in local community or city, logOR = 0.48, 95 % CI [0.17, 0.78], p = 0.002; distant learning, logOR = 0.73, 95 % CI [0.19, 1.28], p = 0.008; COVID-19-related distress, logOR = 1.42, 95 % CI [0.55, 2.29], p = 0.001;). The majority of studies showed no publication bias. Age group moderated the relationship between gender and level of anxiety (F (1,96) = 4.42, p = 0.038), and no other moderator showed significance.

LIMITATIONS

This study does not reveal causality but correlation in nature, and our findings should be interpretated with caution.

CONCLUSIONS

Public health emergencies could bring challenges to the mental health of children and adolescents. Prevention and intervention strategies for children and adolescents with high risks, and family-based and community-based programs should be encouraged to buffer the adverse impact on children and adolescents. This study has been prospectively registered at PROSPERO (registration number: CRD42022316746).

Toward Precision in Critical Care Research: Methods for Observational and Interventional Studies

Critical care trials evaluate the effect of interventions in patients with diverse personal histories and causes of illness, often under the umbrella of heterogeneous clinical syndromes, such as sepsis or acute respiratory distress syndrome. Given this variation, it is reasonable to expect that the effect of treatment on outcomes may differ for individuals with variable characteristics. However, in randomized controlled trials, efficacy is typically assessed by the average treatment effect (ATE), which quantifies the average effect of the intervention on the outcome in the study population. Importantly, the ATE may hide variations of the treatment's effect on a clinical outcome across levels of patient characteristics, which may erroneously lead to the conclusion that an intervention does not work overall when it may in fact benefit certain patients. In this review, we describe methodological approaches for assessing heterogeneity of treatment effect (HTE), including expert-derived subgrouping, data-driven subgrouping, baseline risk modeling, treatment effect modeling, and individual treatment rule estimation. Next, we outline how insights from HTE analyses can be incorporated into the design of clinical trials. Finally, we propose a research agenda for advancing the field and bringing HTE approaches to the bedside.

Healthcare outcomes assessed with observational study designs compared with those assessed in randomized trials: a meta-epidemiological study

BACKGROUND

Researchers and decision-makers often use evidence from randomised controlled trials (RCTs) to determine the efficacy or effectiveness of a treatment or intervention. Studies with observational designs are often used to measure the effectiveness of an intervention in 'real world' scenarios. Numerous study designs and their modifications (including both randomised and observational designs) are used for comparative effectiveness research in an attempt to give an unbiased estimate of whether one treatment is more effective or safer than another for a particular population. An up-to-date systematic analysis is needed to identify differences in effect estimates from RCTs and observational studies. This updated review summarises the results of methodological reviews that compared the effect estimates of observational studies with RCTs from evidence syntheses that addressed the same health research question.

OBJECTIVES

To assess and compare synthesised effect estimates by study type, contrasting RCTs with observational studies. To explore factors that might explain differences in synthesised effect estimates from RCTs versus observational studies (e.g. heterogeneity, type of observational study design, type of intervention, and use of propensity score adjustment). To identify gaps in the existing research comparing effect estimates across different study types.

SEARCH METHODS

We searched MEDLINE, the Cochrane Database of Systematic Reviews, Web of Science databases, and Epistemonikos to May 2022. We checked references, conducted citation searches, and contacted review authors to identify additional reviews.

SELECTION CRITERIA

We included systematic methodological reviews that compared quantitative effect estimates measuring the efficacy or effectiveness of interventions tested in RCTs versus in observational studies. The included reviews compared RCTs to observational studies (including retrospective and prospective cohort, case-control and cross-sectional designs). Reviews were not eligible if they compared RCTs with studies that had used some form of concurrent allocation.

DATA COLLECTION AND ANALYSIS

Using results from observational studies as the reference group, we examined the relative summary effect estimates (risk ratios (RRs), odds ratios (ORs), hazard ratios (HRs), mean differences (MDs), and standardised mean differences (SMDs)) to evaluate whether there was a relatively larger or smaller effect in the ratio of odds ratios (ROR) or ratio of risk ratios (RRR), ratio of hazard ratios (RHR), and difference in (standardised) mean differences (D(S)MD). If an included review did not provide an estimate comparing results from RCTs with observational studies, we generated one by pooling the estimates for observational studies and RCTs, respectively. Across all reviews, we synthesised these ratios to produce a pooled ratio of ratios comparing effect estimates from RCTs with those from observational studies. In overviews of reviews, we estimated the ROR or RRR for each overview using observational studies as the reference category. We appraised the risk of bias in the included reviews (using nine criteria in total). To receive an overall low risk of bias rating, an included review needed: explicit criteria for study selection, a complete sample of studies, and to have controlled for study methodological differences and study heterogeneity. We assessed reviews/overviews not meeting these four criteria as having an overall high risk of bias. We assessed the certainty of the evidence, consisting of multiple evidence syntheses, with the GRADE approach.

MAIN RESULTS

We included 39 systematic reviews and eight overviews of reviews, for a total of 47. Thirty-four of these contributed data to our primary analysis. Based on the available data, we found that the reviews/overviews included 2869 RCTs involving 3,882,115 participants, and 3924 observational studies with 19,499,970 participants. We rated 11 reviews/overviews as having an overall low risk of bias, and 36 as having an unclear or high risk of bias. Our main concerns with the included reviews/overviews were that some did not assess the quality of their included studies, and some failed to account appropriately for differences between study designs - for example, they conducted aggregate analyses of all observational studies rather than separate analyses of cohort and case-control studies. When pooling RORs and RRRs, the ratio of ratios indicated no difference or a very small difference between the effect estimates from RCTs versus from observational studies (ratio of ratios 1.08, 95% confidence interval (CI) 1.01 to 1.15). We rated the certainty of the evidence as low. Twenty-three of 34 reviews reported effect estimates of RCTs and observational studies that were on average in agreement. In a number of subgroup analyses, small differences in the effect estimates were detected: - pharmaceutical interventions only (ratio of ratios 1.12, 95% CI 1.04 to 1.21); - RCTs and observational studies with substantial or high heterogeneity; that is, I2 ≥ 50% (ratio of ratios 1.11, 95% CI 1.04 to 1.18); - no use (ratio of ratios 1.07, 95% CI 1.03 to 1.11) or unclear use (ratio of ratios 1.13, 95% CI 1.03 to 1.25) of propensity score adjustment in observational studies; and - observational studies without further specification of the study design (ratio of ratios 1.06, 95% CI 0.96 to 1.18). We detected no clear difference in other subgroup analyses.

AUTHORS' CONCLUSIONS

We found no difference or a very small difference between effect estimates from RCTs and observational studies. These findings are largely consistent with findings from recently published research. Factors other than study design need to be considered when exploring reasons for a lack of agreement between results of RCTs and observational studies, such as differences in the population, intervention, comparator, and outcomes investigated in the respective studies. Our results underscore that it is important for review authors to consider not only study design, but the level of heterogeneity in meta-analyses of RCTs or observational studies. A better understanding is needed of how these factors might yield estimates reflective of true effectiveness.

Effects of infant motor problems and treatment with physiotherapy on child outcomes at school-age

BACKGROUND

Early motor coordination problems have previously been associated with various developmental outcomes at school-age.

AIMS

Investigate whether and how treatment with physiotherapy may alter associations between early motor problems and subsequent developmental outcomes.

STUDY DESIGN

A prospective whole-population study.

SUBJECTS

1374 children were followed from birth to 8 years.

OUTCOME MEASURES

Early motor functioning was determined with standard neurological examinations at birth and at 5 months. Information on receipt of physiotherapy was collected through parent interviews at 5, 20 and 56 months. Developmental outcomes at 6 and 8 years included motor skills, mental health, cognitive function, and attention regulation and were determined through standard tests, parent reports and observed behavior ratings.

RESULTS

Early motor problems were associated with lower motor skills, cognitive function, and attention regulation at school-age, but not with mental health. In addition to early motor problems, receipt of physiotherapy was independently and negatively related to outcomes at school-age. Accounting for imbalances in covariates, including initial motor scores, via propensity score matching attenuated the adverse effects of receipt of physiotherapy on school-aged outcomes.

CONCLUSIONS

Infant motor problems are associated with motor and cognitive outcomes at school-age. Early motor problems may represent a starting point of a trajectory of difficulties that may lead to a higher risk of problems in multiple developmental domains. No evidence for a beneficial effect of treatment with physiotherapy was found.

Clinical Outcomes of Laparoscopic Versus Laparotomic Distal Gastrectomy in Gastric Cancer Patients: A Multilevel Analysis Based on a Nationwide Administrative Database in Japan

BACKGROUND

The present study compared the short-term outcomes and costs of laparoscopic distal gastrectomy (LDG) with those of open distal gastrectomy (ODG) for gastric cancer using a nationwide administrative database in Japan.

METHOD

Overall, 37,752 patients with gastric cancer who underwent distal gastrectomy at 1074 hospitals in the fiscal year 2012-2013 were evaluated using a diagnosis procedure combination database in Japan. We performed a retrospective analysis via a multilevel analysis (MLA) of the short-term surgical results and costs of the LDG and ODG groups. The models included the age, sex, comorbid complications, smoking, body mass index (BMI), activity of daily living (ADL), stage, and the number of cases of gastrectomy per facility for adjustment. The in-hospital mortality relative to the hospital volume was also compared.

RESULTS

The LDG group required postoperative blood transfusion less frequently and had fewer postoperative complications, shorter hospitalization, and lower operative mortality than the ODG group. While this stage did not correlate with the in-hospital mortality, the surgical method, age, sex, ADL, BMI, comorbidity, and yearly volume showed a correlation. A significant association in the in-hospital mortality was observed between low- and very-high-volume hospitals.

CONCLUSION

In this large nationwide cohort of patients with gastric cancer using an MLA, LDG was shown to be safer with lower mortality and postoperative complication rates than ODG.

Benchmarking Observational Analyses Against Randomized Trials: a Review of Studies Assessing Propensity Score Methods

BACKGROUND

Observational analysis methods can be refined by benchmarking against randomized trials. We reviewed studies systematically comparing observational analyses using propensity score methods against randomized trials to explore whether intervention or outcome characteristics predict agreement between designs.

METHODS

We searched PubMed (from January 1, 2000, to April 30, 2017), the AHRQ Scientific Resource Center Methods Library, reference lists, and bibliographies to identify systematic reviews that compared estimates from observational analyses using propensity scores against randomized trials across three or more clinical topics; reported extractable relative risk (RR) data; and were published in English. One reviewer extracted data from all eligible systematic reviews; a second reviewer verified the extracted data.

RESULTS

Six systematic reviews matching published observational studies to randomized trials, published between 2012 and 2016, met our inclusion criteria. The reviews reported on 127 comparisons overall, in cardiology (29 comparisons), surgery (49), critical care medicine and sepsis (46), nephrology (2), and oncology (1). Disagreements were large (relative RR < 0.7 or > 1.43) in 68 (54%) and statistically significant in 12 (9%) of the comparisons. The degree of agreement varied among reviews but was not strongly associated with intervention or outcome characteristics.

DISCUSSION

Disagreements between observational studies using propensity score methods and randomized trials can occur for many reasons and the available data cannot be used to discern the reasons behind specific disagreements. Better benchmarking of observational analyses using propensity scores (and other causal inference methods) is possible using observational studies that explicitly attempt to emulate target trials.

Effectiveness of tigecycline in the treatment of infections caused by carbapenem-resistant gram-negative bacteria in pediatric liver transplant recipients: A retrospective study

INTRODUCTION

Tigecycline (TGC) is effective for the infections caused by carbapenem-resistant gram-negative bacteria (CRGNB) in adults, but it is not investigated systematically in children because of concern about adverse effects. This study aimed to analyze the effectiveness of TGC in treating CRGNB infections in children after receiving liver transplant.

METHODS

The subjects in this retrospective study were pediatric liver transplant recipients treated with TGC for at least 3 days to fight microbiologically verified CRGNB infection after initial antibiotic failure during the period from January 2014 to May 2018. Clinical and microbiological outcomes were reviewed to evaluate the efficacy and safety of TGC.

RESULTS

Of the 1177 pediatric liver transplant recipients, 13 patients were eligible for inclusion in this analysis. All the patients received TGC at dose of 2 mg/kg every 12 hours for a duration of 10.1 ± 5.1 days on average to treat CRGNB infections, including complicated intra-abdominal infection, ventilator-associated pneumonia, and bloodstream infection. The isolates included Klebsiella pneumoniae (69.2%, 9/13) and Acinetobacter baumannii (30.8%, 4/13). Clinical efficacy was achieved in 84.6% (11/13) and pathogen eradicated in 69.2% (9/13) of the patients. The overall mortality rate was 15.4% (2/13). No TGC-related serious adverse event was reported.

CONCLUSION

Tigecycline can be considered in combination antimicrobial regimen for treating CRGNB-related infections in pediatric liver transplant recipients.

Cost-effectiveness of a mindfulness-based mental health promotion program: economic evaluation of a nonrandomized controlled trial with propensity score matching

BACKGROUND

Mental health promotion programs have been shown to reduce the burden associated with mental distress and prevent the onset of mental disorders, but evidence of cost-effectiveness is scarce.

OBJECTIVE

To evaluate the cost-effectiveness of a mindfulness-based mental health prevention program provided by health coaches in a multi-site field setting in Germany.

METHODS

The single-study based economic evaluation was conducted as part of a nonrandomized controlled trial, comparing the effects of a group-based prevention program to usual care based on propensity score matching. Participants (N = 1166) were recruited via a large statutory health insurance fund. Health outcome was assessed with the Hospital Anxiety and Depression Scale (HADS). Cost outcomes were actually incurred costs compiled from the health insurance' records. Incremental cost-effectiveness ratios (ICER) were analyzed from a societal and a health care perspective for a 12-month time horizon with sampling uncertainty being handled using nonparametric bootstrapping. A cost-effectiveness acceptability curve was graphed to determine the probability of cost-effectiveness at different willingness-to-pay ceiling ratios.

RESULTS

From a societal perspective, prevention was cost-effective compared to usual-care by providing larger effects of 1.97 units on the HADS (95% CI [1.14, 2.81], p < 0.001) at lower mean incremental total costs of €-57 (95% CI [- 634, 480], p = 0.84), yielding an ICER of €-29 (savings) per unit improvement. From a health care perspective, the incremental health benefits were achieved at additional direct costs of €181 for prevention participants (95% CI [40, 318], p = 0.01) with an ICER of €91 per unit improvement on the HADS. Willingness-to-pay for the prevention program to achieve a 95% probability of being cost-effective compared to usual-care, was estimated at €225 per unit improvement on the HADS score from a societal, and €191 from a health care perspective respectively. Sensitivity analyses suggested differential cost-effect-ratios depending on the initial distress of participants.

LIMITATIONS

Due to the complexity of the field trial, it was not feasible to randomize participants and offer an active control condition. This limitation was met by applying a rigorous matching procedure.

CONCLUSIONS

Our results indicate that universal mental health promotion programs in community settings might be a cost-effective strategy to enhance well-being. Differences between the societal and health care perspective underline the call for joint funding in the dissemination of preventive services.

TRIAL REGISTRATION

German Clinical Trials Registration ID: DRKS00006216 (2014/06/11, retrospective registration).

Can propensity score matching be applied to cross-sectional data to evaluate Community-Based Rehabilitation? Results of a survey implementing the WHO's Community-Based Rehabilitation indicators in Vietnam

OBJECTIVES

Community-Based Rehabilitation (CBR) is a multi-sectoral approach working to equalise opportunities and include people with disabilities in all aspects of life. The complexity of CBR and often limited resources lead to challenges when attempting to quantify its effectiveness, with randomisation and longitudinal data rarely possible. Statistical methods, such as propensity score matching (PSM), offer an alternative approach to evaluate a treatment when randomisation is not feasible. The aim of this study is to examine whether PSM can be an effective method to facilitate evaluations of results in CBR when data are cross-sectional.

DESIGN

Cross-sectional survey.

SETTING AND PARTICIPANTS

Data were collected using the WHO's CBR Indicators in Vietnam, with treatment assignment (participating in CBR or not) determined by province of residence. 298 participants were selected through government records.

RESULTS

PSM was conducted using one-to-one nearest neighbour method on 10 covariates. In the unmatched sample, significant differences between groups were found for six of the 10 covariates. PSM successfully adjusted for bias in all covariates in the matched sample (74 matched pairs). A paired t-test compared the outcome of 'community inclusion' (a score based on selected indicators) between CBR and non-CBR participants for both the matched and unmatched samples, with CBR participants found to have significantly worse community inclusion scores (mean=17.86, SD=6.30, 95% CI 16.45 to 19.32) than non-CBR participants (mean=20.93, SD=6.16, 95% CI 19.50 to 22.35); t(73)=3.068, p=0.001. This result did not differ between the matched and unmatched samples.

CONCLUSION

PSM successfully reduced bias between groups, though its application did not affect the tested outcome. PSM should be considered when analysing cross-sectional CBR data, especially for international comparisons where differences between populations may be greater.

Prompt admission to intensive care is associated with improved survival in patients with severe sepsis and/or septic shock

Objective To investigate the association between time from hospital admission to intensive care unit (ICU) admission (door to ICU time) and hospital mortality in patients with sepsis. Methods This retrospective observational study included routinely collected healthcare data from patients with sepsis. The primary endpoint was hospital mortality, defined as the survival status at hospital discharge. Door to ICU time was calculated and included in a multivariable model to investigate its association with mortality. Results Data from 13 115 patients were included for analyses, comprising 10 309 survivors and 2 806 non-survivors. Door to ICU time was significantly longer for non-survivors than survivors (median, 43.0 h [interquartile range, 12.4, 91.3] versus 26.7 h [7.0, 74.2]). In the multivariable regression model, door to ICU time remained significantly associated with mortality (odds ratio [OR] 1.11, 95% confidence interval [CI] 1.006, 1.017) and there was a significant interaction between age and door to ICU time (OR 0.99, 95% CI 0.99, 1.00). Conclusion A shorter time from hospital door to ICU admission was shown to be independently associated with reduced hospital mortality in patients with severe sepsis and/or septic shock.

Alternative methodological approach to randomized trial for surgical procedures routinely used

BACKGROUND

In medical oncology, changes in practices are almost always based on randomized trials but medical history shows that it is different in surgical oncology. In the past, many surgical procedures were routinely performed without a rigorous evaluation of the risk-benefit. To highlight the complexity of developing randomized surgical trials, disquisitions on methodology presented in the medical literature. This is particularly true when we consider breast reconstruction after surgical treatment for breast cancer. It is illusory to perform and conduct a randomized clinical trial (RCT) when a surgical procedure is routinely used by most surgeons.

METHODS

As a case study, we present the scientific rationale and the design of the MAPAM01 trial which evaluates the security of the nipple sparing mastectomy. Other alternative approaches, such as propensity score and CUSUM, are presented.

RESULTS

In this situation, to design surgical trials using alternative methodological approaches present a particularly important challenge both for surgeons and methodologists. Alternative approach to randomized trials can be useful to evaluate surgical procedures routinely used.

CONCLUSION

Close collaboration between surgeons and methodologists is needed to propose appropriate and well-designed surgical trials.

Preliminary experience of tigecycline treatment in critically ill children with ventilator-associated pneumonia

Objective

Ventilator-associated pneumonia (VAP) is a life-threatening complication for children who are treated in a paediatric intensive care unit. Tigecycline treatment of children with VAP has not been well studied. This study aimed to describe tigecycline use in children with VAP in a tertiary care hospital.

Methods

We conducted a retrospective chart review in a tertiary hospital from May 1, 2012 to May 1, 2017.

Results

Twenty-four children (20 girls) with median age of 8 months (range, 27 days to 6 years and 9 months) were treated with tigecycline. In-hospital mortality was 41.7% (10/24). The primary diagnosis was congenital heart disease (15/24). A total of 70.8% (17/24) of patients received a loading dose (1.5 mg/kg), followed by 1 mg/kg every 12 hours. The median duration of tigecycline therapy was 10.75 days (range, 3–21.5 days). Sulperazone was the most frequently used concomitant antibiotic. Eighteen pathogens were isolated in 16 cases. Tigecycline therapy failed in 41.6% (10/24) of patients and 20.8% (5/24) died. The pathogen was eradicated in 37.5% (6/16) of patients. No serious adverse effects were detected.

Conclusion

Tigecycline combined with other agents as salvage therapy in children with VAP is well tolerated. Our preliminary results show a positive clinical response.

Risk of maternal mortality in women with severe anaemia during pregnancy and post partum: a multilevel analysis

BACKGROUND

Anaemia affects as many as half of all pregnant women in low-income and middle-income countries, but the burden of disease and associated maternal mortality are not robustly quantified. We aimed to assess the association between severe anaemia and maternal death with data from the WHO Multicountry Survey on maternal and newborn health.

METHODS

We used multilevel and propensity score regression analyses to establish the relation between severe anaemia and maternal death in 359 health facilities in 29 countries across Latin America, Africa, the Western Pacific, eastern Mediterranean, and southeast Asia. Severe anaemia was defined as antenatal or postnatal haemoglobin concentrations of less than 70 g/L in a blood sample obtained before death. Maternal death was defined as death any time after admission until the seventh day post partum or discharge. In regression analyses, we adjusted for post-partum haemorrhage, general anaesthesia, admission to intensive care, sepsis, pre-eclampsia or eclampsia, thrombocytopenia, shock, massive transfusion, severe oliguria, failure to form clots, and severe acidosis as confounding variables. These variables were used to develop the propensity score.

FINDINGS

312 281 women admitted in labour or with ectopic pregnancies were included in the adjusted multilevel logistic analysis, and 12 470 were included in the propensity score regression analysis. The adjusted odds ratio for maternal death in women with severe anaemia compared with those without severe anaemia was 2·36 (95% CI 1·60-3·48). In the propensity score analysis, severe anaemia was also associated with maternal death (adjusted odds ratio 1·86 [95% CI 1·39-2·49]).

INTERPRETATION

Prevention and treatment of anaemia during pregnancy and post partum should remain a global public health and research priority.

FUNDING

Barts and the London Charity.

[Propensity score: Interests, use and limitations. A practical guide for clinicians]

Propensity scores have been proposed in the early 1980s, and are increasingly used in epidemiology since the 2000s. They are is used to minimize the selection bias in observational studies, leading to a comparability between the exposure groups close to that observed in randomized trials. However, they have important limitations. Besides, new statistical techniques to improve the propensity score performances are more and more complex, while the build and the use of propensity score require a strict methodology to avoid bias, imprecision and non-reproducibility. This overview, designed for clinicians, is aimed at describing the advantages, techniques of use and limitations of propensity scores. A reading grid is provided in order to help interpreting studies using propensity scores.

Antithrombin concentrate use in sepsis-associated disseminated intravascular coagulation: re-evaluation of a 'pendulum effect' drug using a nationwide database

There are four systematic reviews and meta-analyses of trials of antithrombin use for sepsis or critically ill patients published to date with conflicting results. The two studies that showed positive results used data only from septic patients who were also diagnosed with disseminated intravascular coagulation (DIC), whereas the two studies showing negative results included data from all septic and/or critically ill patients in their analyses. We believe that the underlying diseases of the study population must be as homogeneous as possible when evaluating treatment efficacy for sepsis-associated DIC. We published two large-scale antithrombin studies of sepsis-associated DIC using a Japanese nationwide database. The above-mentioned DIC studies reported significant associations between antithrombin use and better 28-day mortality in both populations (DIC-associated with severe pneumonia, n = 9075; and with severe abdominal sepsis, n = 2164). Now is the time to initiate multinational antithrombin trials exclusively among sepsis-associated DIC patients.

Antithrombin Supplementation and Mortality in Sepsis-Induced Disseminated Intravascular Coagulation: A Multicenter Retrospective Observational Study

Supplemental doses of antithrombin (AT) are widely used to treat sepsis-induced disseminated intravascular coagulation (DIC) in Japan. However, evidence on the benefits of AT supplementation for DIC is insufficient. This multicenter retrospective observational study aimed to clarify the effect of AT supplementation on sepsis-induced DIC using propensity score analyses. Data from 3,195 consecutive adult patients admitted to 42 intensive care units for severe sepsis treatment were retrospectively analyzed; 1,784 patients were diagnosed with DIC (n = 715, AT group; n = 1,069, control group). Inverse probability of treatment-weighted propensity score analysis indicated a statistically significant association between AT supplementation and lower in-hospital all-cause mortality (n = 1,784, odds ratio [95% confidence intervals]: 0.748 [0.572-0.978], P = 0.034). However, quintile-stratified propensity score analysis (n = 1,784, odds ratio: 0.823 [0.646-1.050], P = 0.117) and propensity score matching analysis (461 matching pairs, odds ratio: 0.855 [0.649-1.125], P = 0.263) did not show this association. In the early days after intensive care unit admission, the survival rate was statistically higher in the propensity score-matched AT group than in the propensity score-matched control group (P = 0.007). In DIC patients without concomitant heparin administration, similar results were observed. In conclusion, AT supplementation may be associated with reduced in-hospital all-cause mortality in patients with sepsis-induced DIC. However, the statistical robustness of this connection was not strong. In addition, although the number of transfusions needed in patients with AT supplementation increased, severe bleeding complications did not.

Diverse criteria and methods are used to compare treatment effect estimates: a scoping review

OBJECTIVES

To determine what criteria researchers use to assess whether the estimates of effect of an intervention on a dichotomous outcome are different when obtained using different study designs.

STUDY DESIGN AND SETTING

Scoping review of the literature. We included studies of dichotomous outcomes in which authors compared the estimates of effects from different study designs. We performed searches in electronic databases and in the list of references of relevant studies. Two reviewers independently selected studies and abstracted data. We created a list of the criteria used to compare estimates of effects between study designs, described their main features, and classified them using a clinical perspective.

RESULTS

We included 26 studies, from which we identified 24 criteria. Most of the studies focused on comparing estimates from observational studies and randomized controlled trials (n = 19). The most common criteria aimed to determine whether there was a difference or not (n = 18), provided guidance for such a judgment (n = 16), and were based on the point estimates (n = 11). We judged 14 criteria to be appropriate and classified them as either statistically related or clinically related.

CONCLUSION

We found that diverse criteria are used to compare effect estimates between study designs. Familiarity with these would aid in the interpretation of results from different studies regarding the same question.

Meta-analyses including non-randomized studies of therapeutic interventions: a methodological review

Background

There is an increasing number of meta-analyses including data from non-randomized studies for therapeutic evaluation. We aimed to systematically assess the methods used in meta-analyses including non-randomized studies evaluating therapeutic interventions.

Methods

For this methodological review, we searched MEDLINE via PubMed, from January 1, 2013 to December 31, 2013 for meta-analyses including at least one non-randomized study evaluating therapeutic interventions. Etiological assessments and meta-analyses with no comparison group were excluded. Two reviewers independently assessed the general characteristics and key methodological components of the systematic review process and meta-analysis methods.

Results

One hundred eighty eight meta-analyses were selected: 119 included both randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSI) and 69 only NRSI. Half of the meta-analyses (n = 92, 49 %) evaluated non-pharmacological interventions. “Grey literature” was searched for 72 meta-analyses (38 %). An assessment of methodological quality or risk of bias was reported in 135 meta-analyses (72 %) but this assessment considered the risk of confounding bias in only 33 meta-analyses (18 %). In 130 meta-analyses (69 %), the design of each NRSI was not clearly specified. In 131 (70 %), whether crude or adjusted estimates of treatment effect for NRSI were combined was unclear or not reported. Heterogeneity across studies was assessed in 182 meta-analyses (97 %) and further explored in 157 (84 %). Reporting bias was assessed in 127 (68 %).

Conclusions

Some key methodological components of the systematic review process—search for grey literature, description of the type of NRSI included, assessment of risk of confounding bias and reporting of whether crude or adjusted estimates were combined—are not adequately carried out or reported in meta-analyses including NRSI.

Supplemental dose of antithrombin use in disseminated intravascular coagulation patients after abdominal sepsis

The effectiveness of supplemental dose antithrombin administration (1,500 to 3,000 IU/ day) for patients with sepsis-associated disseminated intravascular coagulation (DIC), especially sepsis due to abdominal origin, remains uncertain. This was a retrospective cohort study of patients with mechanically ventilated septic shock and DIC after emergency surgery for perforation of the lower intestinal tract using a nationwide administrative database, Japanese Diagnosis Procedure Combination inpatient database. A total of 2,164 patients treated at 612 hospitals during the 33-month study period between 2010 and 2013 were divided into an antithrombin group (n=1,021) and a control group (n=1,143), from which 518 propensity score-matched pairs were generated. Although there was no significant 28-day mortality difference between the two groups in the unmatched groups (control vs antithrombin: 25.7 vs 22.9 %; difference, 2.8 %; 95 % confidence interval [CI], -0.8-6.4), a significant difference existed between the two groups in propensity-score weighted groups (26.3 vs 21.7 %; difference, 4.6 %; 95 % CI, 2.0-7.1) and propensity-score matched groups (27.6 vs 19.9 %; difference, 7.7 %; 95 % CI, 2.5-12.9). Logistic regression analyses showed a significant association between antithrombin use and lower 28-day mortality in propensity-matched groups (odds ratio, 0.65; 95 % CI, 0.49-0.87). Analysis using the hospital antithrombin-prescribing rate as an instrumental variable showed that receipt of antithrombin was associated with a 6.5 % (95 % CI, 0.05-13.0) reduction in 28-day mortality. Supplemental dose of antithrombin administration may be associated with reduced 28-day mortality in sepsis-associated DIC patients after emergency laparotomy for intestinal perforation.

Performing both propensity score and instrumental variable analyses in observational studies often leads to discrepant results: a systematic review

OBJECTIVES

Propensity score (PS) and instrumental variable (IV) are analytical techniques used to adjust for confounding in observational research. More and more, they seem to be used simultaneously in studies evaluating health interventions. The present review aimed to analyze the agreement between PS and IV results in medical research published to date.

STUDY DESIGN AND SETTING

Review of all published observational studies that evaluated a clinical intervention using simultaneously PS and IV analyses, as identified in MEDLINE and Web of Science.

RESULTS

Thirty-seven studies, most of them published during the previous 5 years, reported 55 comparisons between results from PS and IV analyses. There was a slight/fair agreement between the methods [Cohen's kappa coefficient = 0.21 (95% confidence interval: 0.00, 0.41)]. In 23 cases (42%), results were nonsignificant for one method and significant for the other, and IV analysis results were nonsignificant in most situations (87%).

CONCLUSION

Discrepancies are frequent between PS and IV analyses and can be interpreted in various ways. This suggests that researchers should carefully consider their analytical choices, and readers should be cautious when interpreting results, until further studies clarify the respective roles of the two methods in observational comparative effectiveness research.

The association between fluid balance and mortality in patients with ARDS was modified by serum potassium levels: a retrospective study

Background and Objective. Acute respiratory distress syndrome (ARDS) is characterized by pulmonary edema and may benefit from conservative fluid management. However, conflicting results exist in the literature. The study aimed to investigate the association between mean fluid balance and mortality outcome in ARDS patients who required invasive mechanical ventilation. Methods. The study was a secondary analysis of a prospectively collected dataset obtained from the NHLBI Biologic Specimen and Data Repository Information Coordinating Center. ARDS patients with invasive mechanical ventilation were eligible. Demographic and laboratory data were extracted from the dataset. Multivariable regression model was built by stepwise selection of covariates. A fractional polynomial approach was used to test the linearity of mean fluid balance in the model. The potential interactions of mean fluid balance with other variables were tested. Main Results. A total of 282 patients were eligible for the analysis, including 61 non-survivors with a mortality rate of 21.6%. After stepwise regression analysis, mean fluid balance remained to be an independent predictor of death (OR: 1.00057; 95% CI [1.00034-1.00080]). The two-term model obtained using fractional polynomial analysis was not superior to the linear model. There was significant interaction between mean fluid balance and serum potassium levels (p = 0.011). While the risk of death increased with increasing mean fluid balance at potassium levels of 1.9, 2.9 , 3.9 and 4.9 mmol/l, the risk decreased at potassium level of 5.9 mmol/l. Conclusion. The present study demonstrates that more positive fluid balance in the first 8 days is significantly associated with increased risk of death. However, the relationship between mean fluid balance and mortality can be modified by serum potassium levels. With hyperkalemia, more positive fluid balance is associated with reduced risk of death.

Albumin administration is associated with acute kidney injury in cardiac surgery: a propensity score analysis

Introduction

The risk of acute kidney injury (AKI) with the use of albumin-containing fluids compared to starches in the surgical intensive care setting remains uncertain. We evaluated the adjusted risk of AKI associated with colloids following cardiac surgery.

Methods

We performed a retrospective cohort study of patients undergoing on-pump cardiac surgery in a tertiary care center from 2008 to 2010. We assessed crystalloid and colloid administration until 36 hours after surgery. AKI was defined by the RIFLE (risk, injury, failure, loss and end-stage kidney disease) risk and Acute Kidney Injury Network (AKIN) stage 1 serum creatinine criterion within 96 hours after surgery.

Results

Our cohort included 984 patients with a baseline glomerular filtration rate of 72 ± 19 ml/min/1.73 m². Twenty-three percent had a reduced left ventricular ejection fraction (LVEF), thirty-one percent were diabetics and twenty-three percent underwent heart valve surgery. The incidence of AKI was 5.3% based on RIFLE risk and 12.0% based on the AKIN criterion. AKI was associated with a reduced LVEF, diuretic use, anemia, heart valve surgery, duration of extracorporeal circulation, hemodynamic instability and the use of albumin, pentastarch 10% and transfusions. There was an important dose-dependent AKI risk associated with the administration of albumin, which also paralleled a higher prevalence of concomitant risk factors for AKI. To address any indication bias, we derived a propensity score predicting the likelihood to receive albumin and matched 141 cases to 141 controls with a similar risk profile. In this analysis, albumin was associated with an increased AKI risk (RIFLE risk: 12% versus 5%, P = 0.03; AKIN stage 1: 28% versus 13%, P = 0.002). We repeated this methodology in patients without postoperative hemodynamic instability and still identified an association between the use of albumin and AKI.

Conclusions

Albumin administration was associated with a dose-dependent risk of AKI and remained significant using a propensity score methodology. Future studies should address the safety of albumin-containing fluids on kidney function in patients undergoing cardiac surgery.

Big data and clinical research: focusing on the area of critical care medicine in mainland China

Big data has long been found its way into clinical practice since the advent of information technology era. Medical records and follow-up data can be more efficiently stored and extracted with information technology. Immediately after admission a patient immediately produces a large amount of data including laboratory findings, medications, fluid balance, progressing notes and imaging findings. Clinicians and clinical investigators should make every effort to make full use of the big data that is being continuously generated by electronic medical record (EMR) system and other healthcare databases. At this stage, more training courses on data management and statistical analysis are required before clinicians and clinical investigators can handle big data and translate them into advances in medical science. China is a large country with a population of 1.3 billion and can contribute greatly to clinical researches by providing reliable and high-quality big data.