A cross sectional study of upper extremity strength ten days after a stroke; relationship between patient-reported and objective measures

BACKGROUND Reduced upper extremity function early after a stroke is common, and a combination of strength capacity and patient-reported measures contribute to setting realistic goals. The validity of the patient's perception of upper extremity strength in relation to objective strength assessments early after a stroke needs to be clarified. The objective was to investigate the relationship between perceived upper extremity strength and measured hand strength at ten days post-stroke. METHODS This study of 99 patients with reduced upper extremity function at 3 days post stroke, were consecutively included from a stroke unit to the Stroke Arm Longitudinal Study at the University of Gothenburg, (the SALGOT-study). The correlations between two questions from the Stroke Impact Scale (SIS 1a and 1b), and a dynamometer measure of hand strength values (percentage of normative values) were investigated. In order to explain differences between the two types of measurements, the accordance between perceived strength in a dichotomized SIS and objective measures was explored. In SIS 1a and 1b, 1-3 points correspond to reduced strength (<80% or normative strength values). In SIS 1a and 1b, 4-5 points correspond to normal strength (≥ 80% of normative strength values). RESULTS The correlation between the measured strength values and perceived arm strength was rho 0.82 (p =  <0.001) and with perceived grip strength rho 0.87 (p = <0.001). Using the dichotomized SIS and the 80% cut-off correctly classified arm strength in 81% and grip strength in 84% of the patients, with a sensitivity of 0.86-0.87, a specificity of 0.62-0.77, positive predicted values of 0.87-0.91 and negative predicated values of 0.64-0.67. DISCUSSION The discrepancy between assessed strength capacity and self-perceived strength highlights the importance of including self-perceived assessments early after stroke, in order to increase knowledge of a patient's awareness of functioning or lack thereof. CONCLUSIONS Ten days after stroke in patients without severe cognitive disabilities, this study suggests that despite high correlations between measures, an objective assessment of arm and hand strength does not always reflect the patient's perspective. A combination of self-reported and objective strength assessment is requested to enhance in setting of realistic goals early after stroke. TRIAL REGISTRATION ClinicalTrials.gov: NCT01115348, May 3, 2010.