Proxy ratings from multiple sources: disagreement on the impact of multiple sclerosis on daily life

Background and purpose: The use of self-report measurements may be problematic in patients with limitations that interfere with reliable self-assessment like cognitive impairment, as may be the case in multiple sclerosis (MS). In these situations proxy respondents, such as close relatives or healthcare providers, may provide valuable information. To examine the accuracy and value of healthcare providers and close relatives to assess disease impact of MS.

Methods: MS patients, close relatives and healthcare providers completed the Multiple Sclerosis Impact Scale (MSIS-29) before and after a rehabilitation program. Agreement between outcomes was assessed by calculating mean absolute and directional differences and intraclass correlation coefficients.

Results: Comparison of ratings between patients and proxy respondents revealed low levels of agreement. Close relatives appeared to significantly overestimate the disease impact of MS whereas healthcare providers tended to underestimate the disease impact of MS.

Conclusion: Caution is advised when incorporating close relatives and healthcare providers as proxy respondents in a rehabilitation setting. However, when close relatives are consulted, one should expect a certain level of overestimation of disease impact. When consulting healthcare providers, one should expect a certain level of underestimation of disease impact.