Outcome assessment by central adjudicators in randomised stroke trials: Simulation of differential and non-differential misclassification.

INTRODUCTION: Adjudication of the primary outcome in randomised trials is thought to control misclassification. We investigated the amount of misclassification needed before adjudication changed the primary trial results.Patients (or materials) and methods: We included data from five randomised stroke trials. Differential misclassification was introduced for each primary outcome until the estimated treatment effect was altered. This was simulated 1000 times. We calculated the between-simulation mean proportion of participants that needed to be differentially misclassified to alter the treatment effect. In addition, we simulated hypothetical trials with a binary outcome and varying sample size (1000-10,000), overall event rate (10%-50%) and treatment effect (0.67-0.90). We introduced non-differential misclassification until the treatment effect was non-significant at 5% level. RESULTS: For the five trials, the range of unweighted kappa values were reduced from 0.89-0.97 to 0.65-0.85 before the treatment effect was altered. This corresponded to 2.1%-6% of participants misclassified differentially for trials with a binary outcome. For the hypothetical trials, those with a larger sample size, stronger treatment effect and overall event rate closer to 50% needed a higher proportion of events non-differentially misclassified before the treatment effect became non-significant. DISCUSSION: We found that only a small amount of differential misclassification was required before adjudication altered the primary trial results, whereas a considerable proportion of participants needed to be misclassified non-differentially before adjudication changed trial conclusions. Given that differential misclassification should not occur in trials with sufficient blinding, these results suggest that central adjudication is of most use in studies with unblinded outcome assessment. CONCLUSION: For trials without adequate blinding, central adjudication is vital to control for differential misclassification. However, for large blinded trials, adjudication is of less importance and may not be necessary.

Does the Villalta scale capture the essence of postthrombotic syndrome? A qualitative study of patient experience and expert opinion.

BACKGROUND: The Villalta scale is recommended for diagnosing and grading of postthrombotic syndrome (PTS) in clinical studies, but with limitations in specificity and sensitivity. OBJECTIVES: To explore the typical complaints of PTS through patients experience and expert opinion and relate this to the items of the Villalta scale. PATIENTS/METHODS: A qualitative study design with focus group interviews including patients with PTS and health care workers experienced in PTS patient care. RESULTS: Typical PTS complaints were reflected within four main domains: (a) agonizing discomforts; patients without venous ulcers often described other discomforts than pain; (b) skin changes; these were common and sometimes present before deep vein thrombosis (DVT). Except for venous ulcers, skin changes were considered of less importance; (c) fluctuating heaviness and swelling during the day and with activity; (d) post-DVT concerns; fear of DVT recurrence, health services failing to meet the patients' expectations, and psychological and social restrictions. These findings are not necessarily captured or well reflected in the Villalta scale. CONCLUSION: Our findings indicate that the Villalta scale does not capture typical PTS complaints or their importance to the patients. A revision of the diagnosis and grading should be considered.

Outcome Assessment by Central Adjudicators Versus Site Investigators in Stroke Trials: A Systematic Review and Meta-Analysis.

Background and Purpose- In randomized stroke trials, central adjudication of a trial's primary outcome is regularly implemented. However, recent evidence questions the importance of central adjudication in randomized trials. The aim of this review was to compare outcomes assessed by central adjudicators with outcomes assessed by site investigators. Methods- We included randomized stroke trials where the primary outcome had undergone an assessment by site investigators and central adjudicators. We searched MEDLINE, EMBASE, CENTRAL (Cochrane Central Register of Controlled Trials), Web of Science, PsycINFO, and Google Scholar for eligible studies. We extracted information about the adjudication process as well as the treatment effect for the primary outcome, assessed both by central adjudicators and by site investigators. We calculated the ratio of these treatment effects so that a ratio of these treatment effects >1 indicated that central adjudication resulted in a more beneficial treatment effect than assessment by the site investigator. A random-effects meta-analysis model was fitted to estimate a pooled effect. Results- Fifteen trials, comprising 69 560 participants, were included. The primary outcomes included were stroke (8/15, 53%), a composite event including stroke (6/15, 40%) and functional outcome after stroke measured on the modified Rankin Scale (1/15, 7%). The majority of site investigators were blind to treatment allocation (9/15, 60%). On average, there was no difference in treatment effect estimates based on data from central adjudicators and site investigators (pooled ratio of these treatment effects=1.02; 95% CI, [0.95-1.09]). Conclusions- We found no evidence that central adjudication of the primary outcome in stroke trials had any impact on trial conclusions. This suggests that potential advantages of central adjudication may not outweigh cost and time disadvantages in stroke studies if the primary purpose of adjudication is to ensure validity of trial findings.

Women's values and preferences for thromboprophylaxis during pregnancy: a comparison of direct-choice and decision analysis using patient specific utilities.

BACKGROUND: Women with a history of venous thromboembolism (VTE) have an increased recurrence risk during pregnancy. Low molecular weight heparin (LMWH) reduces this risk, but is costly, burdensome, and may increase risk of bleeding. The decision to start thromboprophylaxis during pregnancy is sensitive to women's values and preferences. Our objective was to compare women's choices using a holistic approach in which they were presented all of the relevant information (direct-choice) versus a personalized decision analysis in which a mathematical model incorporated their preferences and VTE risk to make a treatment recommendation. METHODS: Multicenter, international study. Structured interviews were on women with a history of VTE who were pregnant, planning, or considering pregnancy. Women indicated their willingness to receive thromboprophylaxis based on scenarios using personalized estimates of VTE recurrence and bleeding risks. We also obtained women's values for health outcomes using a visual analog scale. We performed individualized decision analyses for each participant and compared model recommendations to decisions made when presented with the direct-choice exercise. RESULTS: Of the 123 women in the study, the decision model recommended LMWH for 51 women and recommended against LMWH for 72 women. 12% (6/51) of women for whom the decision model recommended thromboprophylaxis chose not to take LMWH; 72% (52/72) of women for whom the decision model recommended against thromboprophylaxis chose LMWH. CONCLUSIONS: We observed a high degree of discordance between decisions in the direct-choice exercise and decision model recommendations. Although which approach best captures individuals' true values remains uncertain, personalized decision support tools presenting results based on personalized risks and values may improve decision making.

Assessing burden of illness following acute deep vein thrombosis: data quality, reliability and validity of the Norwegian version of VEINES-QOL/Sym, a disease-specific questionnaire.

The data quality, reliability and validity of the Norwegian version of VEINES-QOL/Sym were assessed in 74 patients with deep vein thrombosis (DVT). This patient-reported questionnaire produces two scale scores of venous disease-specific quality of life and venous symptoms. Items had low levels of missing data. Item-total correlations ranged from 0.41 to 0.78 with the exception of 0.29 for the symptom item 'night cramps'. Internal consistency was supported by Cronbach's alpha of 0.88 and 0.94 for VEINES-Sym and VEINES-QOL, respectively. Test-retest reliability assessed for 40 patients gave intraclass correlation coefficients of 0.83 and 0.88 for VEINES-Sym and VEINES-QOL, respectively. Assessment of correlation between the two scales and other clinical measures supports the construct validity of the scales. The results indicate acceptable internal consistency, test-retest reliability and validity of the Norwegian version of the VEINES-QOL/Sym questionnaire in patients with DVT. The results follow those of previous studies, and support the use of VEINES-QOL/Sym in the evaluation of patient outcomes and burden of illness in clinical studies of venous thrombosis.