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

Abstract

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.

Keywords: Stroke; Thrombectomy.

Figure 1

Distribution of premorbid disability, recanalization status, and clinical outcome at discharge in cohorts of patients with 90 day missing clinical outcome data (MOD) versus those with data available. (A) Total German Stroke Registry-Endovascular Treatment (GSR-ET) cohort: MOD was associated with higher premorbid disability. Premorbid modified Rankin Scale (mRS) score was available in 10 195/10 502 (97.1%) patients with 90 day outcome available and in 1995/2580 (77.3%) patients with MOD. MOD was associated with successful recanalization (thrombolysis in cerebral infarction (TICI) scale score 2b–3); TICI was available in 10 173/10 502 (96.9%) patients with 90 day outcome available and in 2404/2580 (93.2%) patients with MOD. MOD was inversely associated with higher disability at discharge from the treating hospital as of mRS 3–6 versus 0–2; mRS at discharge was available in 9957/10 502 (94.8%) patients with 90 day outcome available and in 1858/2580 (72.0%) patients with MOD. (B) Subgroup analysis of patients discharged from hospital alive: comparison of patients with clinical outcome at 90 day follow-up available (n=7710) versus patients with MOD despite complete baseline documentation (age, sex, admission National Institutes of Health Stroke Scale score, intravenous thrombolysis, TICI, and mRS at discharge) (n=1706). MOD was associated with higher premorbid disability; premorbid mRS was available in 7606/7710 (98.7%) patients discharged from hospital alive with 90 day outcome available and in 1665/1706 (97.6%) patients with MOD despite complete baseline documentation. MOD was not significantly associated with successful recanalization (TICI 2b–3); TICI was available in 7537/7710 (97.8%) patients discharged from hospital alive with 90 day outcome available and in 1706/1706 (100.0%) patients with MOD despite complete baseline documentation. MOD was associated with higher disability at discharge from the treating hospital as of mRS 3–5 versus 0–2.

Figure 2

Factors associated with missing 90 day clinical outcome in the total German Stroke Registry-Endovascular Treatment (GSR-ET) cohort and the subgroup of patients discharged from hospital alive with missing clinical outcome data (MOD) despite well documented baseline characteristics. ORs with 95% CI and P values of factors associated with MOD resulting from univariate logistic regression analyses. Circles=point estimates of factors associated with MOD in the total GSR-ET cohort; squares=subgroup analysis with point estimates of factors associated with MOD in the subgroup of patients who were discharged from hospital alive and had MOD despite well documented baseline characteristics (age, sex, admission National Institutes of Health Stroke Scale (NIHSS) score, intravenous thrombolysis (IVT), TICI, and mRS at discharge). P values indicating significance of predictors with a threshold of <0.05. MT, mechanical thrombectomy; mRS, modified Rankin scale score.