Introduction to PREP2

 

Purpose
PREP2 stands for Predict Recovery Potential and is a revised prediction tool for predicting upper limb functional outcomes within 12 weeks after stroke. PREP2 starts within 3 days of stroke and requires 3 simple steps. Patients are given one of four upper limb predictions for functional outcome, which can be used to focus rehabilitation. The purpose of this section is to ensure an in-depth understanding of the PREP2 prediction tool and how PREP2 predictions can be used in clinical practice.


What is PREP2?
PREP2 is a prediction tool for predicting upper limb functional outcomes after stroke. You can download a one-page summary here.

 

Step 1

  • Establish a patient’s SAFE score by grading Shoulder Abduction and Finger Extension power using the MRC grades out of 5, and sum for a SAFE score out of 10
  • If the patient’s SAFE score is at least 5 within 3 days of stroke symptom onset, an Excellent or Good prediction can be given depending on the patient’s age
  • Around two-thirds of patients only require this step in order to obtain a prediction

Step 2

  • If the patient has a SAFE score less than 5 on Day 3 then obtain the NIHSS score on Day 3
  • Test the function of motor pathways between the stroke-affected side of the brain and the affected arm using transcranial magnetic stimulation (TMS) on Day 3 – 7 after stroke
  • If MEP positive (MEP+) provide a Good prediction of upper limb outcome

Step 3

  • For all MEP negative (MEP-) patients
  • Give a Limited prediction if the patient’s NIHSS score was less than 7 on Day 3
  • Give a Poor prediction if the patient’s NIHSS score was 7 or more on Day 3


Assessments

SAFE score

The SAFE score is calculated by scoring Shoulder Abduction and Finger Extension of the paretic upper limb using the Medical Research Council grades. For more information see: SAFE score


TMS assessment

Transcranial magnetic stimulation (TMS) is a safe, painless, non-invasive way of activating neurons in the cortex of the brain. It provides a safe way of testing whether the descending motor pathways from the brain to the affected upper limb are working. TMS testing is carried out by staff who have completed PREP2 TMS training.


NIHSS assessment

The National Institutes of Health Stroke Scale (NIHSS) is a 15 item neurological scale used to evaluate overall stroke severity stroke. For more information see: NIHSS assessment.


Prediction categories
Summaries of PREP2 predictions for the patient and their family, and the clinical team can be downloaded here.

Excellent
The patient is most likely to have an excellent upper limb outcome within the next 3 months. They can expect to be using their upper limb fairly normally for most activities of daily living. As these patients are often mildly affected, and soon discharged from hospital, they can be prescribed a self-directed hand and arm exercise programme to help them reach their potential. The rehabilitation focus is to promote normal function.

Good
The patient is most likely to have a good upper limb outcome within the next 3 months. They can expect to be using their hand for most activities of daily living, though function may remain affected by slowness, weakness or clumsiness. Upper limb rehabilitation can focus on improving function by increasing strength, coordination and fine control. Repetitive practice of movement and everyday tasks should help. The affected hand and arm should be used for safe daily activities, and compensation with the stronger arm should be minimised. The rehabilitation focus is to promote function.

Limited
The patient is most likely to have a limited upper limb outcome within the next 3 months. They may possibly recover grasp function, but recovery of dextrous hand function is unlikely. Upper limb rehabilitation can focus on improving strength, active range of motion, and joint flexibility, and adapting daily activities to incorporate both upper limbs when necessary to achieve a task. The rehabilitation focus is to promote movement.

Poor
The patient is most likely to have a poor upper limb outcome within the next 3 months. They may regain some movement, but are unlikely to recover useful upper limb function. They may be able to use their weaker hand to stabilise objects in bimanual tasks. Upper limb rehabilitation can focus on prevention of secondary complications, such as pain, spasticity, and shoulder instability, and helping the patient to do everyday activities with the stronger hand and arm. The rehabilitation focus is to promote compensation.


Who is PREP2 for?

  • The PREP2 prediction tool has been developed and validated with patients who are at least 18 years old and have had a recent stroke (excluding cerebellar and bilateral stroke) that has caused weakness in one upper limb.
  • PREP2 can be used with patients who have had an ischaemic or haemorrhagic stroke, and patients with previous stroke. It can be used for patients treated with thrombolysis and/or thrombectomy.
  • PREP2 may not be suitable for patients with severe aphasia or cognitive impairment that limits their ability to understand the tests involved, or if they have a SAFE score < 5 on Day 3 but have contraindications to TMS.


Who performs PREP2?
In general, the SAFE score, TMS and NIHSS can be performed by trained therapists. The wider clinical team and subsequent rehabilitation services also need to know how to use and support PREP2 predictions, so they can provide continuity of care.


Why use PREP2?
Clinicians often find it difficult to accurately predict functional outcomes, especially for patients with moderate to severe initial impairment. Currently, no single clinical measure or neurological biomarker is able to accurately predict motor recovery or outcome for all patients. Approaches using combinations of measures and biomarkers are needed.

Being able to predict upper limb motor outcomes for individual patients soon after stroke could help in several ways. For example, it could help with realistic goal setting and discharge planning for clinicians and patients. It could also help with the appropriate allocation of time and resources by both the patient and the therapy team.

Using the prediction tool increases therapist confidence and allows them to tailor upper limb therapy for individual patients. It is also linked to a reduced length of hospital stay, without any negative effects on patient outcomes or satisfaction. For more details read “Predicting recovery potential for individual patients increases rehabilitation efficiency after stroke”


Essential reading


Recommended reading

Quiz

Click here for a practice quiz to assess your learning on the Introduction to PREP2 section.

Once the practice quiz has been completed with at least 70% correct you will be emailed a link to the final quiz for this section.

If you pass the final quiz with at least 80% correct you will be emailed a certificate of completion for the Introduction to PREP2 section. There is no limit to the number of attempts for the practice or final quiz.