High prevalence of potential biases threatens the interpretation of trials in patients with chronic disease

Real world data in mechanical thrombectomy: who are we losing to follow-up?

BACKGROUND

Missing outcome data (MOD) is a common problem in clinical trials and registries, and a potential bias when drawing conclusions from these data. Identifying factors associated with MOD may help to increase follow-up rates and assess the need for imputation strategies. We investigated MOD in a multicenter, prospective registry study of mechanical thrombectomy (MT) in large vessel occlusion ischemic stroke.

METHODS

13 082 patients enrolled in the German Stroke Registry-Endovascular Treatment from May 2015 to December 2021 were analyzed with regard to MOD (90 day modified Rankin Scale, mRS). Univariate logistic regression analyses identified factors unbalanced between patients with and without MOD. Subgroup analyses were performed to identify patients for whom increased efforts to perform clinical follow-up after hospital discharge are needed.

RESULTS

We identified 19.7% (2580/13 082) of patients with MOD at the 90 day follow-up. MOD was more common with higher pre-stroke disability (mRS 3-5, 32.2% vs mRS 0-2, 13.7%; P<0.001), absence of bridging intravenous thrombolysis, longer time to treatment, and in patients with high post-stroke disability at discharge (mRS 3-5 vs 0-2: OR 1.234 (95% CI 1.107 to 1.375); P<0.001). In contrast, MOD was less common with futile recanalization (thrombolysis in cerebral infarction (TICI) score of 0-2a, 12.4% vs TICI 2b-3, 15.0%; P=0.001). In patients discharged alive with well documented baseline characteristics, shorter hospital stay (OR 0.992 (95% CI 0.985 to 0.998); P=0.010) and discharge to institutional care or hospital (OR 1.754 (95% CI 1.558 to 1.976); P<0.001) were associated with MOD.

CONCLUSION

MOD in routine care MT registry data was not random. Increased efforts to perform clinical follow-up are needed, especially in the case of higher pre-stroke and post-stroke disability and discharge to hospital or institutional care.

TRIAL REGISTRATION

NCT03356392.

Evidence selection for a prescription drug's benefit-harm assessment: challenges and recommendations

OBJECTIVES

To describe challenges and make recommendations for researchers in how they select evidence to quantitatively assess a prescription drug's benefits and harms.

STUDY DESIGN AND SETTING

These challenges and recommendations are based on our recent experience conducting a benefit-harm assessment for the prescription drug roflumilast. We considered the selection of evidence to quantify (1) the drug's treatment effects in patients, (2) the patient population's baseline risks for beneficial and harmful outcomes without treatment, and (3) the patient population's preferences for these beneficial effects and harms. These are fundamental steps for most benefit-harm assessment methods.

RESULTS

We identify critical issues in selecting evidence for each of these steps. We justify in particular the need to incorporate (1) clinical trials for the drug's specific treatment effect; (2) observational studies with the most valid, precise, and applicable effect estimates for the baseline risk; and (3) flexible weighting approaches for balancing the drug benefits and harms.

CONCLUSION

We identify challenges and make recommendations for selecting evidence at the critical steps in a prescription drug's benefit-harm assessment. Our findings should assist other researchers conducting these assessments for prescription drugs, which could help regulators, medical professionals, and patients make better decisions about prescription drug use.

Addressing multimorbidity in evidence integration and synthesis

To minimize bias, clinical practice guidelines (CPG) for managing patients with multiple conditions should be informed by well-planned syntheses of the totality of the relevant evidence by means of systematic reviews and meta-analyses. However, deficiencies along the entire evidentiary pathway hinder the development of evidence-based CPGs. Published reports of trials and observational studies often do not provide usable data on treatment effect heterogeneity, perhaps because their design, analysis and presentation is seldom geared towards informing on how multimorbidity modifies the effect of treatments. Systematic reviews and meta-analyses inherit all the limitations of their building blocks and introduce additional of their own, including selection biases at the level of the included studies, ecological biases, and analytical challenges. To generate recommendations to help negotiate some of the challenges in synthesizing the primary literature, so that the results of the evidence synthesis is applicable to the care of those with multiple conditions. Informal group process. We have built upon established general guidance, and provide additional recommendations specific to systematic reviews that could improve the CPGs for multimorbid patients. We suggest that following the additional recommendations is good practice, but acknowledge that not all proposed recommendations are of equal importance, validity and feasibility, and that further work is needed to test and refine the recommendations.

A framework for crafting clinical practice guidelines that are relevant to the care and management of people with multimorbidity

Many patients of all ages have multiple conditions, yet clinicians often lack explicit guidance on how to approach clinical decision-making for such people. Most recommendations from clinical practice guidelines (CPGs) focus on the management of single diseases, and may be harmful or impractical for patients with multimorbidity. A major barrier to the development of guidance for people with multimorbidity stems from the fact that the evidence underlying CPGs derives from studies predominantly focused on the management of a single disease. In this paper, the investigators from the Improving Guidelines for Multimorbid Patients Study Group present consensus-based recommendations for guideline developers to make guidelines more useful for the care of people with multimorbidity. In an iterative process informed by review of key literature and experience, we drafted a list of issues and possible approaches for addressing important coexisting conditions in each step of the guideline development process, with a focus on considering relevant interactions between the conditions, their treatments and their outcomes. The recommended approaches address consideration of coexisting conditions at all major steps in CPG development, from nominating and scoping the topic, commissioning the work group, refining key questions, ranking importance of outcomes, conducting systematic reviews, assessing quality of evidence and applicability, summarizing benefits and harms, to formulating recommendations and grading their strength. The list of issues and recommendations was reviewed and refined iteratively by stakeholders. This framework acknowledges the challenges faced by CPG developers who must make complex judgments in the absence of high-quality or direct evidence. These recommendations require validation through implementation, evaluation and refinement.

Protection of pharmacological postconditioning in liver surgery: results of a prospective randomized controlled trial

OBJECTIVES

: To elucidate the possible organ-protective effect of pharmacological postconditioning in patients undergoing liver resection with inflow occlusion.

BACKGROUND

: Inflow occlusion reduces blood loss during liver transection in selected patients but is potentially harmful due to ischemia-reperfusion injury. Preventive strategies include the use of repetitive short periods of ischemia interrupted by a reperfusion phase (intermittent clamping), application of a short period of ischemia before transection (ischemic preconditioning), or pharmacological preconditioning before transection. Whether intervention after resection (postconditioning) may confer protection is unknown.

METHODS

: A 3 arm, prospective, randomized trial was designed for patients undergoing liver resection with inflow occlusion to compare the effects of pharmacological postconditioning with the volatile anesthetic agent sevoflurane (n = 48), intermittent clamping (n = 50), or no protective intervention (continuous inflow occlusion, n = 17). Endpoints included peak serum aspartate transaminase level, postoperative complications, and hospital stay. All patients were intravenously anesthetized with propofol. In patients with postconditioning, propofol infusion was stopped upon reperfusion and replaced with sevoflurane for 10 minutes.

RESULTS

: Compared with the control group, both postconditioning (P = 0.044) and intermittent clamping (P = 0.015) significantly reduced aspartate transaminase levels. The risk of complications was significantly decreased by postconditioning, odds ratio, 0.08 [95% confidence interval (CI), 0.02-0.36; P = 0.001]) and intermittent clamping, odds ratio, 0.50 [95% CI, 0.26-0.96; P = 0.038], compared with controls. Both interventions reduced length of hospital stay, postconditioning -4 days [95% CI, -6 to -1; P = 0.009], and intermittent clamping -2 days, [95% CI, -4 to 0; P = 0.019].

CONCLUSIONS

: Pharmacological postconditioning reduces organ injury and postoperative complications. This easily applicable strategy should be used in patients with prolonged continuous inflow occlusion.

Informing evidence-based decision-making for patients with comorbidity: availability of necessary information in clinical trials for chronic diseases

BACKGROUND

The population with multiple chronic conditions is growing. Prior studies indicate that patients with comorbidities are frequently excluded from trials but do not address whether information is available in trials to draw conclusions about treatment effects for these patients.

METHODS AND FINDINGS

We conducted a literature survey of trials from 11 Cochrane Reviews for four chronic diseases (diabetes, heart failure, chronic obstructive pulmonary disease, and stroke). The Cochrane Reviews systematically identified and summarized trials on the effectiveness of diuretics, metformin, anticoagulants, longacting beta-agonists alone or in combination with inhaled corticosteroids, lipid lowering agents, exercise and diet. Eligible studies were reports of trials included in the Cochrane reviews and additional papers that described the methods of these trials. We assessed the exclusion and inclusion of people with comorbidities, the reporting of comorbidities, and whether comorbidities were considered as potential modifiers of treatment effects. Overall, the replicability of both the inclusion criteria (mean [standard deviation (SD)]: 6.0 (2.1), range (min-max): 1-9.5) and exclusion criteria (mean(SD): 5.3 (2.1), range: 1-9.5) was only moderate. Trials excluded patients with many common comorbidities. The proportion of exclusions for comorbidities ranged from 0-42 percent for heart failure, 0-55 percent for COPD, 0-44 percent for diabetes, and 0-39 percent for stroke. Seventy of the 161 trials (43.5%) described the prevalence of any comorbidity among participants with the index disease. The reporting of comorbidities in trials was very limited, in terms of reporting an operational definition and method of ascertainment for the presence of comorbidity and treatments for the comorbidity. It was even less common that the trials assessed whether comorbidities were potential modifiers of treatment effects.

CONCLUSIONS

Comorbidities receive little attention in chronic disease trials. Given the public health importance of people with multiple chronic conditions, trials should better report on comorbidities and assess the effect comorbidities have on treatment outcomes.

Comparisons against baseline within randomised groups are often used and can be highly misleading

Background

In randomised trials, rather than comparing randomised groups directly some researchers carry out a significance test comparing a baseline with a final measurement separately in each group.

Methods

We give several examples where this has been done. We use simulation to demonstrate that the procedure is invalid and also show this algebraically.

Results

This approach is biased and invalid, producing conclusions which are, potentially, highly misleading. The actual alpha level of this procedure can be as high as 0.50 for two groups and 0.75 for three.

Conclusions

Randomised groups should be compared directly by two-sample methods and separate tests against baseline are highly misleading.