Reliability of the Acutely Estimated Premorbid Modified Rankin Scale for Stroke Treatment Decision Making

Premorbid functional status is an important factor in acute stroke treatment decision making. Determining the modified Rankin Score (mRS) accurately may be difficult due to deficits from stroke and lack of collateral information in the acute setting. Data on the reliability of the premorbid mRS in "real-world" practice outside of clinical trial or registry settings are limited.

A retrospective study at a high volume academic primary stroke center. For patients with acute ischemic stroke treated with alteplase between July 2012 and July 2016, hospital electronic records were reviewed for detailed inpatient occupational therapist (OT) assessment of premorbid functional status to determine mRS (OT-mRS). This was compared with premorbid mRS determined at acute emergency department assessment (Acute-mRS). Kappa statistic and Lin's concordance correlation coefficient was used to calculate agreement between Acute-mRS and OT-mRS.

Among stroke patients treated with alteplase over the 4 years period, OT-mRS was available for 312 patients (79.0%), the mean age was 75.5 years (male 51.9%). 82.4%, 11.9%, and 5.8% of patients had Acute-mRS of 0-1, 2, and ≥3; while 84.9%, 8.0%, and 6.7% had OT-mRS of 0-1, 2, and ≥3, respectively. The agreement between Acute-mRS and OT-mRS was 83.3%, with κ = .64 and correlation coefficient r = .87 (95% CI .841-.896, P < .05).

There was at least moderate agreement between Acute-mRS prior to thrombolysis and OT-mRS obtained by detailed assessment later. The number of patients with premorbid disability was small and may have positively influenced the agreement between the 2 scores.