PREP2 Algorithm Predictions Are Correct at 2 Years Poststroke for Most Patients

So fucking what if your predictions are correct? That just means you completely and totally failed in getting your patients 100% recovered. And why with that failure track record do you still have a job? 

PREP2 Algorithm Predictions Are Correct at 2 Years Poststroke for Most Patients 

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Marie-Claire Smith, PhD*, Suzanne J. Ackerley, PhD*, P. Alan Barber, FRACP, ...

First Published July 3, 2019 Research Article

https://doi.org/10.1177/1545968319860481

Article information

Abstract

Background. The PREP2 algorithm combines clinical and neurophysiological measures to predict upper-limb (UL) motor outcomes 3 months poststroke, using 4 prediction categories based on Action Research Arm Test (ARAT) scores. The algorithm was accurate at 3 months for 75% of participants in a previous validation study.  
Objective. This study aimed to evaluate whether PREP2 predictions made at baseline are correct 2 years poststroke. We also assessed whether patients’ UL performance remained stable, improved, or worsened between 3 months and 2 years after stroke.  
Methods. This is a follow-up study of 192 participants recruited and assessed in the original PREP2 validation study. Participants who completed assessments 3 months poststroke (n = 157) were invited to complete follow-up assessments at 2 years poststroke for the present study. UL outcomes were assessed with the ARAT, upper extremity Fugl-Meyer Scale, and Motor Activity Log. Results. A total of 86 participants completed 2-year follow-up assessments in this study. PREP2 predictions made at baseline were correct for 69/86 (80%) participants 2 years poststroke, and PREP2 UL outcome category was stable between 3 months and 2 years poststroke for 71/86 (83%). There was no difference in age, stroke severity, or comorbidities among patients whose category remained stable, improved, or deteriorated.  
Conclusions. PREP2 algorithm predictions made within days of stroke are correct at both 3 months and 2 years poststroke for most patients. Further investigation may be useful to identify which patients are likely to improve, remain stable, or deteriorate between 3 months and 2 years.

Keywords upper limb, motor, prognosis, outcome, biomarkers, stroke, rehabilitation

Introduction

Recovery of upper-limb (UL) function after stroke is important for regaining independence in activities of daily living.¹ Early prediction of UL outcome may increase rehabilitation efficiency by tailoring therapy for individual patients.² However, making accurate predictions for individual patients based on clinical measures alone can be difficult.³
The PREP2 algorithm combines clinical and neurophysiological measures within a few days of stroke to make predictions for UL functional outcomes at 3 months poststroke (http://www.presto.auckland.ac.nz).⁴ Patients are predicted to achieve 1 of 4 functional UL outcome categories: Excellent, Good, Limited, or Poor. These UL functional outcome categories are based on ranges of scores on the Action Research Arm Test (ARAT), which were previously established through hypothesis free cluster analysis⁵ and subsequently refined (Table 1).⁴ Information that can be offered to patients in each predicted outcome category is provided in Table 1. This includes the expected level of UL function by 3 months poststroke and a suggested rehabilitation focus.

Table 1. PREP2 Prediction Category Description and Suggested Rehabilitation Focus.

Table 1. PREP2 Prediction Category Description and Suggested Rehabilitation Focus.

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The PREP2 algorithm starts by grading paretic UL Shoulder Abduction and Finger Extension (SAFE) strength at day 3 poststroke using the Medical Research Council grades (Figure 1). If the sum of these grades is ≥5/10, the patient’s age (<80 or ≥80 years) is taken into account to predict either an Excellent or Good UL functional outcome at 3 months. For patients with a SAFE score <5, ipsilesional corticospinal system function is evaluated with transcranial magnetic stimulation. Patients with motor evoked potentials (MEP+) in the first dorsal interosseus or extensor carpi radialis muscles of the paretic UL are predicted to achieve a Good UL functional outcome, regardless of the initial motor impairment. Patients without MEPs (MEP−) are predicted to achieve a Limited or Poor functional UL outcome, depending on overall stroke severity measured at day 3 poststroke with the National Institute of Health Stroke Scale. At 3 months poststroke, PREP2 predictions are correct for 75% of patients, with predictions too optimistic for most of the remaining 25%.⁴

Figure 1. The PREP2 algorithm. The SAFE score is the sum of the Medical Research Council grades for Shoulder Abduction and Finger Extension, out of 5, for a total SAFE score out of 10. MEP+ means that MEPs can be elicited from the paretic extensor carpi radialis and/or first dorsal interosseous muscles of the paretic upper limb (UL) using transcranial magnetic stimulation. The algorithm predicts 1 of 4 possible UL functional outcomes at 3 months poststroke. Each prediction category is associated with rehabilitation goals that can be used to tailor UL therapy.² The colored dots represent, proportionally, PREP2 algorithm accuracy. The dots are color coded based on the outcome category actually achieved 3 months poststroke (green, Excellent; blue, Good; orange, Limited; red, Poor).
Abbreviations: MEP, motor evoked potential; NIHSS, National Institutes of Health Stroke Scale; SAFE, Shoulder Abduction and Finger Extension.

Most motor recovery after stroke occurs within the first 3 months.^6-12 However, a plateau in motor performance might not occur until 5 to 6 months poststroke for some patients with more severe initial impairment.^13,14 To the best of our knowledge, no longitudinal studies have tracked UL performance from early after stroke for more than 6 months. This means that little is known about what happens to UL impairment, function, and use once a patient reaches plateau and moves into the early chronic phase of stroke. Learned nonuse may contribute to deterioration in UL motor function from the peak motor performance achieved at plateau, particularly for patients with more severe UL impairment.^14,15 This could make it difficult to discern whether the benefits of UL therapy reported in studies with patients at the chronic stage are a result of improvements over and above participants’ previous maximal function or a result of participants being boosted back up to their previous best after deterioration since the subacute stage.
The aim of this study was to determine whether PREP2 predictions made within a few days poststroke were correct 2 years after stroke and determine whether UL performance improves, deteriorates, or remains stable between 3 months and 2 years after stroke. We hypothesized that PREP2 predictions made at baseline would be correct at 2 years poststroke and PREP2 outcome category and UL motor performance would remain stable between 3 months and 2 years after stroke.
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