Comparing outcome scales for unruptured intracranial aneurysms: a prospective cohort study

Outcomes on the modified Rankin Scale (mRS) are commonly used to guide and evaluate the management of unruptured intracranial aneurysms (uIA). However, the mRS is unlikely to measure all the relevant aspects of the clinical health of a patient. The current study therefore investigated the relationship between the mRS and additional measures of outcome. Between January 2011 and January 2016 patients with a new diagnosis of uIA were prospectively examined at referral and 12-month follow-up. Assessment included the Physical and Mental Component Scores of the Short Form 36 (SF-36), the computerized driver screening instrument DriveSafe (DS), and the mRS. Minimally Important Change (MIC) for each outcome measure was used to identify adverse outcomes for individual patients. A total of 128 patients (98 surgery; 30 untreated) completed the minimal dataset for analysis. In the surgical group, 6% (95% CI 3–14%) experienced morbidity at 12-months, as defined by the MIC for mRS. This risk rate increased to 51% (95% CI 41–61%) when defined as an MIC on any outcome. A combined MIC also identified a downgrade in outcomes, not detectable on the mRS, in 42% (95% CI 26–61%) of untreated patients. Correlation and regression analyses were unable to identify any significant relationships between the different outcomes instruments. In sum, there were considerably more adverse outcomes reported by quality of life (SF-36) and functional (DS) instruments than by the mRS for either treated or untreated uIA. To obtain a more complete representation of patient outcomes requires administration of a multi-dimensional assessment.