Challenges of Estimating Accurate Prevalence of Arm Weakness Early After Stroke

What possible use is there of this in getting patients recovered? To me this is just an excuse ready made for your doctors and therapists to pull out when you don't recover. 

Challenges of Estimating Accurate Prevalence of Arm Weakness Early After Stroke

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Lisa A. Simpson, MSc, Kathryn S. Hayward, PhD, Moira McPeake, BSc (PT), ...

First Published July 28, 2021 Research Article 

https://doi.org/10.1177/15459683211028240

Article information

Abstract

Background. 

Recent studies have reported lower statistics of upper limb (UL) weakness (48-57%) compared to widely cited values collected over 2 decades ago (70-80%). Objective. To explore potential factors contributing to the accuracy of prevalence values of UL weakness using a case study from a single regional centre. 

Methods. 

All patients admitted to the acute stroke unit with suspected diagnosis of stroke were screened from February 2016 to August 2017. Upper limb weakness was captured (a) prospectively using the Shoulder Abduction and Finger Extension (SAFE) score performed by unit physical therapists within 7 days post-stroke and (b) retrospectively via chart review using the National Institutes of Health Stroke Scale (NIHSS) arm score at admission and 24 hours post-admission.  

Results. 

A total of 656 patients were admitted with a first-ever stroke, and 621 (95%) individuals were administered the SAFE score. A total of 40% of individuals had UL weakness using the SAFE score (SAFE ≤8) at a mean time of 1.9 (SD 1.5) days post-stroke. In the same sample, 57% and 49% had UL weakness using the admission and 24-hour post-admission NIHSS arm score, respectively.  

Conclusions. 

The accuracy of population-level UL weakness prevalence values can be affected by weakness measure and score cut-off, time post-stroke weakness is captured, sample characteristics and use of single or multiple sites. Researchers using prevalence values for clinical trial planning should consider these attributes when using prevalence data for estimating recruitment rates and resource needs.

Keywords

stroke, upper extremity, prevalence, rehabilitation

Introduction

The most frequently cited statistic for the prevalence of upper limb (UL) weakness in acute stroke is approximately 70%, provided by data from the Copenhagen Stroke Study (n = 421) collected in 1991/92.¹ Other studies from this era have provided even higher prevalence of UL weakness that ranged from 73-77%.^2-4 It is possible that the overall prevalence and profile of UL weakness has changed since the above data were collected given advancements in the medical management of acute stroke. For instance, one large unselected study of first-ever stroke (n = 642) collected in 2009/10 in Sweden estimated only 48% of their sample had UL motor impairment.⁵ Screening data collected in 2017/2018 from an ongoing longitudinal study in Switzerland reported only 57% of consecutive patients with ischaemic stroke (n = 845) experienced UL weakness.⁶ It is interesting to ponder whether these more recent studies reflect a true change in UL weakness/motor impairment prevalence, differences in sample and/or study methods and/or the increasing use of reperfusion therapies. Capturing a true prevalence value is challenging. Selected arm weakness/impairment measure, threshold scores adopted, time of weakness assessment and number of sites data are collected from have the potential to make a large impact on the accuracy of prevalence estimation aiming to capture the true effect of stroke on the UL. Adding to the complexity is that rehabilitation researchers hoping to use prevalence values to inform clinical trial planning may be interested in prevalence studies that align with their population of interest, planned time post-stroke at recruitment and type of institution where their research will take place. The purpose of this study is to explore potential factors contributing to the accuracy of prevalence values of UL weakness using a case study from a single regional centre. Specifically, we used screening data for a prospective longitudinal cohort study to estimate UL weakness prevalence values using two different weakness measures at three different time points post-stroke to highlight the challenges of obtaining true prevalence values and/or values that may inform clinical trial planning.

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