Patient-centered outcomes: translating clinical efficacy into benefits on health-related quality of life

Abstract

Background: Multiple sclerosis (MS) is a neurodegenerative disease associated with marked impairments in health-related quality of life (HRQoL). Although standard clinical end points such as the Expanded Disability Status Scale and annualized relapse rate remain useful in assessing MS activity and severity, these measures do not fully reflect the patient's experience of the disease. The impact of MS on employment status, social and family relationships, sexual satisfaction, pain, fatigue, enjoyment of life, vision, bladder/bowel control, cognition, and emotional well-being can be profound and may influence the patient's adherence to long-term treatment. Generic HRQoL instruments such as the Medical Outcome Survey Short Form-36 and the Functional Status Questionnaire initially were used in MS studies. However, MS-specific and hybrid instruments that possess greater sensitivity now have been developed.

Expert clinical opinion: The effects of interferon-beta on HRQoL have been evaluated in several studies, and improvements on some dimensions of HRQoL, particularly in patients with mild disability, have been reported. Two large pivotal studies of natalizumab prospectively included HRQoL assessments as tertiary efficacy end points. The impact of natalizumab on HRQoL outcomes in patients with relapsing-remitting MS was evident at 2 years regardless of sustained disease progression or relapse status.

Future directions: Patient-centered outcomes are becoming increasingly important in evaluations of MS therapies. Therefore, inclusion of HRQoL assessments in pivotal clinical studies eventually should become standard practice. Increasing our understanding of minimally important clinical change in these measures will be an important step in helping researchers and clinicians interpret these results beyond statistical significance.