Evidence-based medicine-When observational studies are better than randomized controlled trials

Reading Difficulties in Individuals with Homonymous Visual Field Defects: A Systematic Review of Reported Interventions

Reading difficulties are amongst the most commonly reported problems in individuals with homonymous visual field defects (HVFDs). To be able to provide guidance for healthcare professionals considering offering reading training, researchers in this field and interested individuals with HVFDs, this systematic review aims to (1) provide an overview of the contextual and intervention characteristics of all published HVFD interventions and (2) generate insights into the different reading outcome measures that these studies adopted. A search on PsycINFO, MEDLINE and Web of Science was conducted up to February 2, 2023. All intervention studies for HVFD in which reading was measured were included. Data was collected about the intervention type, session duration, number of sessions, the intensity, duration, circumstance of the interventions, country in which the intervention was studied and reading measures. Sixty records are included, describing 70 interventions in total of which 21 are specifically reading interventions. Overall, adjusted saccadic behaviour interventions occur most in the literature. A wide range within all intervention characteristics was observed. Forty-nine records reported task-performance reading measures, and 33 records reported self-reported reading measures. The majority of task-performance measures are based on self-developed paragraph reading tasks with a time-based outcome measure (e.g. words per minute). Future research could benefit from making use of validated reading tests, approaching the measurement of reading mixed-methods and providing participants the possibility to supply outcomes relevant to them.

Adherence to the Mediterranean Diet in Saudi Arabia and Its Association with Socioeconomic Status and Depression

Background and Objectives: Several RCTs have reported significant reductions in depression symptoms with the Mediterranean diet (MedDiet), but observational studies have reported inconsistent findings. Moreover, studies have rarely investigated the mediating role of socioeconomic status (SES), including objective material status, in adherence to the MedDiet and its impact on depressive symptoms in the same population. Therefore, this cross-sectional study investigated the relationship between adherence to the MedDiet, socioeconomic factors, and depression severity. Materials and Methods: A cross-sectional online survey was conducted between June and December 2022 across Saudia Arabia. The snowball sampling technique was used to recruit participants aged ≥18 years. Mediterranean diet adherence screener (MEDAS) and Patient Health Questionnaire-9 (PHQ-9) were used to assess adherence to the MedDiet and depression severity. An SES index, validated in the Saudi Arabian context, was used to assess SES. The data were analyzed using the Chi-square and Pearson's correlation tests. Results: Only 21% of our study population (n = 467) was MedDiet adherent. Adherence was significantly associated with education (p = 0.014) but not employment status among traditional SES indicators. Similarly, only television ownership (p = 0.009) was associated with MedDiet adherence among the 20 objective material possessions investigated. Nonetheless, the MedDiet-adherent group had a significantly lower PHQ-9 score than the non-adherent group (6.16 ± 0.68 vs. 8.35 ± 0.31, p = 0.002). A moderate but significantly negative correlation between MEDAS and PHQ-9 scores (r = -0.16, p = 0.001) was noted. Conclusions: MedDiet adherence was associated with lower depression severity scores. In addition to education and television ownership, adherence was not associated with any objective indicators of SES.

Randomized controlled trials: not always the "gold standard" for evidence in obstetrics and gynecology

Randomized controlled trials are considered the "gold standard" for therapeutic interventions, and it is not uncommon for sweeping changes in medical practice to follow positive results from such trials. However, randomized controlled trials are not without their limitations. Physicians frequently view randomized controlled trials as infallible, whereas they tend to dismiss evidence derived from sources other than randomized controlled trials as less credible or reliable. In several situations in obstetrics and gynecology, there are no randomized controlled trials to help guide the clinician. In these circumstances, it is important to evaluate the entire body of evidence including observational studies, rather than dismiss interventions altogether simply because no randomized controlled trials exist. Randomized controlled trials and observational studies should be viewed as complementary rather than at odds with each other. Some reversals in widely adopted clinical practice have recently been implemented following subsequent studies that contradicted the outcomes of major randomized controlled trials. The most notable of these was the withdrawal from the market of 17-hydroxyprogesterone caproate for preterm birth prevention. Such reversals could potentially have been averted if the inherent limitations of randomized controlled trials were carefully considered before implementing these universal practice changes. This Clinical Opinion underscores the limitations of an exclusive reliance on randomized controlled trials while disregarding other evidence in determining how best to care for patients. Solutions are proposed that advocate that clinicians adopt a more balanced perspective that considers the entirety of the available medical evidence and the individual patient characteristics, needs, and wishes.

Diet-derived circulating antioxidants and risk of epilepsy: A study combining metabolomics and mendelian randomization

Background

Previous studies offer inconclusive results on the association between diet-derived circulating antioxidants and epilepsy.

Objective

This study aims to assess oxidative stress presence in epilepsy patients' circulation and investigate the causal link between diet-derived circulating antioxidants and epilepsy.

Methods

Untargeted metabolomics analysis was conducted on plasma samples from 62 epileptic patients and 20 healthy individuals to evaluate oxidative stress based on metabolite alterations in epilepsy patients' circulation. Two-sample Mendelian Randomization (MR) analysis examined the causation between diet-derived circulating antioxidants (measured by absolute levels and relative metabolite concentrations) and epilepsy, utilizing the inverse-variance weighted (IVW) method as the primary outcome, with complementary MR analysis methods (MR Egger, weighted median, weighted mode, and simple mode).

Results

Untargeted metabolomics analysis revealed elevated circulating oxidizing metabolites (palmitic acid, oleic acid, linoleic acid, and myristic acid) and reduced reducing metabolites (glutamine) in epilepsy patients, providing robust evidence of oxidative stress. The IVW analysis indicated significantly reduced epilepsy risk (odds ratio: 0.552; 95% confidence interval: 0.335-0.905, P = 0.018) with genetically determined higher absolute circulating β-carotene. However, other diet-derived circulating antioxidants (lycopene, retinol, ascorbic acid, and selenium) and antioxidant metabolites (α-tocopherol, γ-tocopherol, ascorbic acid, and retinol) did not significantly associate with epilepsy risk. Additional MR analysis methods and heterogeneity assessments confirmed the results' robustness.

Conclusion

This study provides compelling evidence of oxidative stress in epilepsy patients' circulation. However, the majority of diet-derived circulating antioxidants (lycopene, retinol, ascorbic acid, vitamin E, and selenium) are unlikely to causally associate with reduced epilepsy risk, except for β-carotene.

Prognostic models: What the statistician wants the clinician to know

Prognostic model building is a process that begins much earlier than data analysis and ends later than when a model is reached. It requires careful delineation of a clinical question, methodical planning of the approach and attentive exploration of the data before attempting model building. Once following these important initial steps, the researcher may postulate a model to describe the process of interest and build such model. Once built, the model will need to be checked, validated and the exercise may take the researcher back a few steps - for instance, to adapt the model to fit a variable that displays a 'curved' pattern - to then return to check and validate the model again. To interpret and report the results it is vital to relate the output to the original question, to be transparent in the methodology followed and to understand the limitations of the data and the approach.

Causal effects of circulating lipids and lipid-lowering drugs on the risk of urinary stones: a Mendelian randomization study

Background

Previous studies have yielded conflicting findings regarding the association between circulating lipids and lipid-lowering drugs with urinary stones, and the causal relationship between the two remains inconclusive.

Objective

This study aimed to assess the causal relationship between circulating lipids (Triglycerides [TG], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], apolipoprotein A [APOA], apolipoprotein B [APOB] and Pure hypercholesterolaemia), lipid-lowering drugs (HMGCR [HMG-CoA reductase] inhibitors and PCSK9[Proprotein Convertase Subtilisin/Kexin Type 9] inhibitors) and the risk of urinary stones, using genetic data.

Methods

Genetic instrumental variables (GIVs) for circulating lipids and lipid-lowering drugs were obtained from the UK Biobank and existing literature. Outcome data were extracted from a genetic association database with 3,625 urinary stone cases and 459,308 controls. Two-sample MR analysis, employing the TwoSampleMR software package in R 4.2.3, was conducted to assess the associations between multiple exposures. The primary outcome was determined using the inverse variance weighted (IVW) method for the causal relationship between exposure and outcome, while additional methods such as MR-Egger, weighted median, simple mode, and weighted mode were utilized as supplementary analyses. Robustness of the Mendelian Randomization (MR) analysis results was assessed through leave-one-out analysis and funnel plots.

Results

The MR analysis revealed a significant association between elevated TG levels per 1 standard deviation and the occurrence of urinary stones (odds ratio [OR]: 1.002, 95% confidence interval [CI]: 1.000-1.003, P = 0.010). However, no significant association was observed between factors other than TG exposure and the risk of urinary stone occurrence across all methods(LDL-C: [OR], 1.001; 95% [CI], 1.000-1.003, P=0.132;HDL-C: [OR], 0.999; 95% [CI], 0.998-1.000, P=0.151;APOA:[OR] being 1.000 (95% [CI], 0.999-1.001, P=0.721;APOB: [OR] of 1.001 (95% [CI], 1.000-1.002, P=0.058;Pure hypercholesterolaemia: [OR] of 1.015 (95% [CI], 0.976-1.055, P=0.455) and lipid-lowering drugs (HMGCR inhibitors: [OR], 0.997; 95% [CI], 0.990-1.003, P=0.301 and PCSK9 inhibitors:[OR], 1.002; 95% [CI], 1.000-1.005, P=0.099).

Conclusion

Our findings provide conclusive evidence supporting a causal relationship between an increased risk of urinary stones and elevated serum TG levels. However, we did not find a significant association between urinary stone occurrence and the levels of LDL-C, HDL-C, APOA, APOB, Pure hypercholesterolaemia and lipid-lowering drugs.

Acute kidney injury associated with nephrotoxic drugs in critically ill patients: a multicenter cohort study using electronic health record data

Background

Nephrotoxic drugs frequently cause acute kidney injury (AKI) in adult intensive care unit (ICU) patients. However, there is a lack of large pharmaco-epidemiological studies investigating the associations between drugs and AKI. Importantly, AKI risk factors may also be indications or contraindications for drugs and thereby confound the associations. Here, we aimed to estimate the associations between commonly administered (potentially) nephrotoxic drug groups and AKI in adult ICU patients whilst adjusting for confounding.

Methods

In this multicenter retrospective observational study, we included adult ICU admissions to 13 Dutch ICUs. We measured exposure to 44 predefined (potentially) nephrotoxic drug groups. The outcome was AKI during ICU admission. The association between each drug group and AKI was estimated using etiological cause-specific Cox proportional hazard models and adjusted for confounding. To facilitate an (independent) informed assessment of residual confounding, we manually identified drug group-specific confounders using a large drug knowledge database and existing literature.

Results

We included 92 616 ICU admissions, of which 13 492 developed AKI (15%). We found 14 drug groups to be associated with a higher hazard of AKI after adjustment for confounding. These groups included established (e.g. aminoglycosides), less well established (e.g. opioids) and controversial (e.g. sympathomimetics with α- and β-effect) drugs.

Conclusions

The results confirm existing insights and provide new ones regarding drug associated AKI in adult ICU patients. These insights warrant caution and extra monitoring when prescribing nephrotoxic drugs in the ICU and indicate which drug groups require further investigation.

Outcomes after early treatment with hydroxychloroquine and azithromycin: An analysis of a database of 30,423 COVID-19 patients

Background

Many studies have evaluated the use of hydroxychloroquine in COVID-19. Most retrospective observational studies demonstrate a benefit of using HCQ on mortality, but not most randomized clinical trials.

Methods

We analyzed raw data collected from a cohort of 30,423 patients with COVID-19 cared for at IHU Méditerranée Infection in Marseille France and extracted from the DRYAD open data platform. We performed univariate and multivariable logistic regressions with all-cause mortality within six weeks. Multivariable logistic regressions were adjusted for sex, age group (<50, 50-69, 70-89 and ​> ​89 years), periods (or variants), and type of patient management.

Results

Among 30,202 patients for whom information on treatment was available, 191/23,172 (0.82%) patients treated with HCQ-AZ died, compared to 344/7030 (4.89%) who did not receive treatment with HCQ-AZ. HCQ-AZ therapy was associated with a lower mortality than treatment without HCQ-AZ (odds ratio (OR) 0.16; 95% confidence interval (CI), 0.14-0.19). After adjustment for sex, age, period, and patient management, HCQ-AZ was associated with a significantly lower mortality rate (adjusted OR (aOR) 0.55, 95% CI 0.45-0.68). On a subsample of 21,664 patients with available variant information, results remained robust after adjustment on sex, age, patient management and variant (aOR 0.55; 95% CI 0.44-0.69). On a subsample of 16,063 patients, HCQ-AZ was still associated with a significantly lower mortality rate (aOR 0.47, 95%CI 0.29-0.75) after adjustment for sex, age, period, patient management, vaccination status and comorbidities.

Conclusion

Analysis of this large online database showed that HCQ-AZ was consistently associated with the lowest mortality.

Cannabidiol as an adjuvant treatment in adults with drug-resistant focal epilepsy

Cannabidiol oil (CBD) has been approved as an anti-seizure medication for the treatment of uncommon types of epilepsy, occurring in children: Dravet syndrome, Lennox-Gastaut syndrome, and Tuberous Sclerosis Complex. There are few publications in relation to use the CBD in adult patients with focal drug-resistant epilepsy. The objective of this study was to evaluate the efficacy, tolerability, safety, and quality of life, of adjuvant treatment with CBD, in adult patients with drug-resistant focal epilepsy for at least 6 months. An open, observational, prospective cohort study was conducted using a before-after design (time series) in adult patients undergoing outpatient follow-up in a public hospital in Buenos Aires, Argentina. From a total of 44 patients, 5% of patients were seizure-free, 32% of patients reduced more than 80% of their seizures and 87% of patients reduced 50% of their monthly seizures. Eleven percent presented a decrease of less than 50% in seizure frequency. The average final dose was 335 mg/d orally administered. Thirty-four percent of patients reported mild adverse events and no patient reported severe adverse effects. At the end of the study, we found in most patients a significant improvement in the quality of life, in all the items evaluated. Adjuvant treatment with CBD in adult patients with drug-resistant focal epilepsy was effective, safe, well tolerated, and associated with a significant improvement in their quality of life.

Effects of sugammadex versus neostigmine on postoperative nausea and vomiting after general anesthesia in adult patients:a single-center retrospective study

We aimed to compare the effect of sugammadex to that of neostigmine with respect to the occurrence of postoperative nausea and vomiting (PONV) during the first 24 h following general anesthesia. This retrospective cohort study included patients who underwent elective surgery under general anesthesia in 2020 at an academic medical center in Seoul, South Korea. The exposure groups were determined according to whether the patient received sugammadex or neostigmine as a reversal agent. The primary outcome was PONV occurrence during the first 24 h postoperatively (overall). The association between the type of reversal agent and primary outcome was investigated using logistic regression while adjusting for confounding variables using stabilized inverse probability of treatment weighting (sIPTW). Of the 10,912 patients included in this study, 5,918 (54.2%) received sugammadex. Sugammadex was associated with a significantly lower incidence of overall PONV (15.8% vs. 17.7%; odds ratio, 0.87; 95% confidence interval [CI], 0.79-0.97; P = 0.010) after sIPTW. In conclusion, compared with neostigmine/glycopyrrolate, sugammadex use has a lower risk of PONV during the first 24 h following general anesthesia.

Critical Appraisal Tools to Aid Pharmacists in Evidence-Based Practice: A Narrative Review

Background

Pharmacists and allied health researchers need to ensure that their practice is supported by current, evidence-based information. Critical appraisal tools have been developed to aid in this process.

Objectives

To analyze the current landscape of critical appraisal tools and to create an aid for pharmacists and other allied health researchers to use in comparing various tools and choosing the best one for each particular study design.

Data Sources

A literature search of the PubMed, University of Toronto Libraries, and Cochrane Library databases was conducted in December 2021, to generate an up-to-date list of critical appraisal tools. The tools were then summarized in a descriptive table.

Study Selection and Data Extraction

Review articles, original manuscripts, and tool webpages were examined to develop a comparison chart based on the user-friendliness, efficiency, comprehensiveness, and reliability of each tool.

Results

Fourteen tools were found through the literature search. These tools were compared using the findings of included review articles, and a comparison chart was created to aid pharmacists and allied health researchers in selecting the appropriate tool for their practice.

Conclusions

There are many standardized critical appraisal tools that can help in assessing the quality of evidence, and the summary list of tools developed and reported here can help health care researchers to compare among them and choose the best one. No tools were found that have been specifically adapted to serve the needs of pharmacists when assessing scientific articles. Future research should examine how existing critical appraisal tools can better identify common data elements that are essential to evidence-based decision-making in pharmacy practice.

Adverse Reactions of COVID-19 Vaccines: A Scoping Review of Observational Studies

The COVID-19 pandemic had a severe global impact. A range of campaigns and activities, including vaccines, are being implemented to counteract this pandemic. Using observational data, the goal of this scoping review is to identify adverse events connected with COVID-19 vaccinations. We conduct a scoping study and searched three databases from the start of the COVID-19 pandemic in 2020 through June 2022. Based on our criteria and searched keywords, the review included eleven papers in total, with the majority of the studies being conducted in developed countries. The study populations varied and included general community populations, healthcare professionals, military forces, and patients with systemic lupus and cancer. This study includes vaccines from Pfizer-BioNTech, Oxford-AstraZeneca, Sinopharm, and Moderna. The COVID-19 vaccine-related adverse events were classified into three types: local side effects, systemic side effects, and other side effects such as allergies. The adverse reactions to COVID-19 vaccines are mild to moderate in severity, with no significant influence or interference in individual daily activities and no unique patterns in cause of death among vaccine-related deaths. According to the findings of these investigations, the COVID-19 vaccine is safe to administer and induces protection. It is vital to convey accurate information to the public about vaccination side effects, potential adverse responses, and the safety level of the vaccines supplied. Multiple strategies must be implemented at the individual, organizational, and population levels to eliminate vaccine hesitance. Future studies could investigate the vaccine's effect on people of various ages and medical conditions.

Causal analysis of serum polyunsaturated fatty acids with juvenile idiopathic arthritis and ocular comorbidity

BACKGROUND & OBJECTIVE

To investigate the causal effects of plasma Polyunsaturated fatty acids (PUFAs) on the risk of juvenile idiopathic arthritis (JIA) and ocular comorbidity through Mendelian randomization (MR) analysis.

METHODS

Genetic variants (formerly single nucleotide polymorphisms, SNPs) that are strongly associated with PUFAs levels (P < 5×10-8) were selected as instrumental variables. Summary-level MR was performed with outcome estimates for JIA (n = 31,142) and JIA associated iridocyclitis (n = 94,197). The inverse variance-weighted (IVW) method was employed as the main approach to combine the estimation for each SNP. Two set of models with summary statistics were conducted and multiple sensitivity analyses were applied for testing of pleiotropic bias.

RESULTS

In model 1, genetically predicted n-6 PUFAs linoleic acid (LA) and arachidonic acid (AA) were associated with lower and higher risk of JIA associated iridocyclitis using IVW (ORLA = 0.940, 95% CI: 0.895-0.988, P = 0.015; ORAA = 1.053, 95% CI: 1.007-1.101, P = 0.024). No such association was observed between each plasma PUFAs and JIA susceptibility (P > 0.05). In further MR analysis, results from model 2 also showed a consistent trend. Besides, multiple sensitivity analyses revealed that there was no obvious evidence for unknown pleiotropy (P > 0.05).

CONCLUSIONS

Our MR study provides genetic evidence on the possible causality that plasma LA level might protect against JIA associated iridocyclitis, whereas AA was responsible for opposite effect.

Cardiac arrest centres: what, who, when, and where?

PURPOSE OF REVIEW

Cardiac arrest centres (CACs) may play a key role in providing postresuscitation care, thereby improving outcomes in out-of-hospital cardiac arrest (OHCA). There is no consensus on CAC definitions or the optimal CAC transport strategy despite advances in research. This review provides an updated overview of CACs, highlighting evidence gaps and future research directions.

RECENT FINDINGS

CAC definitions vary worldwide but often feature 24/7 percutaneous coronary intervention capability, targeted temperature management, neuroprognostication, intensive care, education, and research within a centralized, high-volume hospital. Significant evidence exists for benefits of CACs related to regionalization. A recent meta-analysis demonstrated clearly improved survival with favourable neurological outcome and survival among patients transported to CACs with conclusions robust to sensitivity analyses. However, scarce data exists regarding 'who', 'when', and 'where' for CAC transport strategies. Evidence for OHCA patients without ST elevation postresuscitation to be transported to CACs remains unclear. Preliminary evidence demonstrated greater benefit from CACs among patients with shockable rhythms. Randomized controlled trials should evaluate specific strategies, such as bypassing nearest hospitals and interhospital transfer.

SUMMARY

Real-world study designs evaluating CAC transport strategies are needed. OHCA patients with underlying culprit lesions, such as those with ST-elevation myocardial infarction (STEMI) or initial shockable rhythms, will likely benefit the most from CACs.

Incremental and Personalized Hemodialysis Start: A New Standard of Care

Introduction

Incremental hemodialysis (iHD) may attenuate “dialysis shock” and reduce costs, preserving quality of life. It is considered difficult to reconcile with HD wards’ routine; fear of underdialysis and increasing mortality are additional concerns. The aim of this study was to evaluate mortality, morbidity, and costs in a large HD ward where iHD is the standard of HD start.

Methods

This observational study included all incident HD patients in 2017 to 2021, stratified according to HD start: iHD (1–2 sessions/wk), decremental HD (dHD, 3 sessions/wk at start, later reduced), or standard (3 sessions/wk). Results were compared with data recorded in the same unit before the incremental program (2015–2017) and with a propensity score-matched cohort from the French Renal Epidemiology and Information Network (REIN) registry.

Results

A total of 158 patients started HD in 2017 to 2021, 57.6% on iHD, 8.9% dHD, and 33.5% standard HD schedule. Patients on the standard schedule had lower initial estimated glomerular filtration rate (eGFR) (5 vs. 7 ml/min per 1.72 m², P = 0.003). We found no survival differences according to period of start (same center) and propensity score matching (REIN). Patients intensively followed in the pre-HD period were more likely to start on iHD-dHD. Persistence on iHD-dHD was about 50% at 1 year and 35% at 2 years. Hospitalization rates and time to first hospitalization or death did not differ between the schedules. The iHD-dHD policy allowed a 16% cost saving, even accounting for supplemental biochemical tests.

Conclusion

Our study reveals that iHD can be a new standard of care, as it is safe and feasible in up to two-thirds of patients on incident HD.

Pragmatic Clinical Studies: An Emerging Clinical Research Discipline for Improving Evidence-Based Practice of Cardiovascular Diseases in Asia

Pragmatic clinical studies, as an emerging clinical research discipline, include a wide range of studies that are largely embedded with routine clinical practice aiming to evaluate comparative effectiveness and safety of different clinical intervention strategies. In this review, we described the evolution of the conceptual framework of pragmatic clinical studies, shared perspectives on the importance of pragmatic clinical studies for cardiovascular diseases as a complement to conventional randomized controlled trials, as well as highlighted the specific importance of pragmatic clinical research in improving evidence-based practice for cardiovascular disease managements in Asia.

Pragmatic clinical studies, an emerging clinical research discipline, include a wide range of studies that are largely embedded with routine clinical practice and aim to evaluate the comparative effectiveness and safety of different clinical intervention strategies. Increased availability and quality of electronic medical/health records drives the development of pragmatic clinical studies. In this review, we describe evolution of the conceptual framework of pragmatic clinical studies and share perspectives on the importance of pragmatic clinical studies in evidence-based practice for cardiovascular diseases, as a complement to conventional randomized controlled trials. We also highlight specific needs of pragmatic clinical studies in improving evidence-based practice for cardiovascular disease in Asian countries. The main challenges of pragmatic clinical studies are discussed briefly in this review.

Learning healthcare systems and rapid learning in radiation oncology: Where are we and where are we going?

Learning health systems and rapid-learning are well developed at the conceptual level. The promise of rapidly generating and applying evidence where conventional clinical trials would not usually be practical is attractive in principle. The connectivity of modern digital healthcare information systems and the increasing volumes of data accrued through patients' care pathways offer an ideal platform for the concepts. This is particularly true in radiotherapy where modern treatment planning and image guidance offers a precise digital record of the treatment planned and delivered. The vision is of real-world data, accrued by patients during their routine care, being used to drive programmes of continuous clinical improvement as part of standard practice. This vision, however, is not yet a reality in radiotherapy departments. In this article we review the literature to explore why this is not the case, identify barriers to its implementation, and suggest how wider clinical application might be achieved.

Strength of clinical evidence leading to approval of novel cancer medicines in Europe: A systematic review and data synthesis

We aimed to evaluate the quality of clinical evidence that substantiated approval of cancer medicines by the European Medicines Agency (EMA) in the last decade. We performed a systematic review and data synthesis of EMA documents in agreement with PRISMA guidelines. We included the European Public Assessment Reports, Summaries of Product Characteristics, and published randomized controlled trials (RCTs) on anti-cancer drugs approved by EMA from 2010 to 2019, and excluded drugs not indicated for targeting solid or hematological tumors and non-innovative treatments. We synthesized frequencies of approvals differentiating between unblinded and blinded RCTs with and without overall survival (OS) as a predefined primary outcome measure. We assessed the frequency of post-approval RCTs for indications without at least one RCT at the time of approval. Of 199 approvals, 159 (80%) were supported by at least one RCT, 63 (32%) by at least one RCT having OS as the primary or co-primary endpoint, 74 (37%) by at least one blinded RCT, and 30 (15%) by at least one blinded RCT having OS as the primary or co-primary endpoint. Whereas 40 approvals (20%) were not supported by any RCT and, of those, 9 (22%) were followed by a post-approval RCT. While the majority of approvals of cancer medicines approved by EMA was supported by at least one RCT, we noted substantial methodological heterogeneity of the studies. Clinical trial registration: PROSPERO registration number CRD42020206669.

Pharmacoepidemiology for nephrologists (part 2): potential biases and how to overcome them

Observational pharmacoepidemiological studies using routinely collected healthcare data are increasingly being used in the field of nephrology to answer questions on the effectiveness and safety of medications. This review discusses a number of biases that may arise in such studies and proposes solutions to minimize them during the design or statistical analysis phase. We first describe designs to handle confounding by indication (e.g. active comparator design) and methods to investigate the influence of unmeasured confounding, such as the E-value, the use of negative control outcomes and control cohorts. We next discuss prevalent user and immortal time biases in pharmacoepidemiology research and how these can be prevented by focussing on incident users and applying either landmarking, using a time-varying exposure, or the cloning, censoring and weighting method. Lastly, we briefly discuss the common issues with missing data and misclassification bias. When these biases are properly accounted for, pharmacoepidemiological observational studies can provide valuable information for clinical practice.

Points of attention when conducting etiological research

Epidemiological studies often aim to investigate the causal contribution of a risk factor to a disease or other outcome. In etiological research, one is usually interested in the (biological) mechanism(s) underlying the studied relationship. Inappropriate conduct of an etiological study may have major implications for the correctness of the results and interpretation of the findings. Therefore, in this paper, we aim to describe step by step how etiological research should be carried out, together with its  common pitfalls. These steps involve finding and formulating a well-defined etiological research question, choosing an appropriate study design including a suitable comparison group, adequate modelling, and adequate reporting and interpretation of the results.

Evidence-based medicine-When observational studies are better than randomized controlled trials

In evidence-based medicine, clinical research questions may be addressed by different study designs. This article describes when randomized controlled trials (RCT) are needed and when observational studies are more suitable. According to the Centre for Evidence-Based Medicine, study designs can be divided into analytic and non-analytic (descriptive) study designs. Analytic studies aim to quantify the association of an intervention (eg, treatment) or a naturally occurring exposure with an outcome. They can be subdivided into experimental (ie, RCT) and observational studies. The RCT is the best study design to evaluate the intended effect of an intervention, because the randomization procedure breaks the link between the allocation of the intervention and patient prognosis. If the randomization of the intervention or exposure is not possible, one needs to depend on observational analytic studies, but these studies usually suffer from bias and confounding. If the study focuses on unintended effects of interventions (ie, effects of an intervention that are not intended or foreseen), observational analytic studies are the most suitable study designs, provided that there is no link between the allocation of the intervention and the unintended effect. Furthermore, non-analytic studies (ie, descriptive studies) also rely on observational study designs. In summary, RCTs and observational study designs are inherently different, and depending on the study aim, they each have their own strengths and weaknesses.