Washington, DC—With worsening symptoms and increasingly unpredictable attacks, the burden for patients with secondary-progressive multiple sclerosis (MS) is undeniable, and studies have shown that accumulating levels of disability experienced by patients with MS have a direct impact on their quality of life. Although patient-reported outcome (PRO) measures can provide insight into patients’ perception of their disease, little is known about the type and frequency of PRO instruments used in studies of patients with secondary-progressing MS.
“Currently, there is a lack of validated PRO instruments and measures that are consistently used in secondary-progressive MS studies,” said Crystal Watson, Director, Health Economics and Outcomes Research, Biogen Idec, Cambridge, MA, at the 2015 American Academy of Neurology annual meeting.
“Therefore, more validated instruments are needed within this population so they can be standardized and established as best practice across secondary-progressive MS studies and potentially clinical practice,” Ms Watson said.
The instruments used to measure the impact of MS on a patient’s daily life can be generic, such as the Short Form-36 (SF-36); disease-specific, such as the Multiple Sclerosis Impact Scale-29 (MSIS-29); or symptom-specific, such as the Fatigue Severity Scale.
“Several PRO instruments have been validated in relapsing-remitting multiple sclerosis (RRMS), and are widely used to monitor RRMS impact across various quality of life, health utility, cognitive, and physical functions,” she told Value-Based Care in Neurology. “But the frequency of instruments used in secondary-progressive MS remains an unknown.”
Ms Watson and colleagues conducted a systematic literature review in PubMed, Embase, and ClinicalTrials.gov, and at key neurology and MS conferences. Their searches covered the literature between July 2004 and June 2014, and conference abstracts from July 2009 through June 2014.
Researchers classified PRO instruments into 3 categories, including generic, MS-specific, and symptom-specific.
The analysis included 55 studies, and 30 abstracts from key conferences. In 12 of these studies, 9 different generic instruments were used, with SF-36 being the most common (N = 3), followed by the EuroQol-5D (N = 2). In 28 studies, 13 types of MS-specific instruments were used. MSIS-29 was the most frequently (N = 10) used MS-specific instrument, followed by the Multiple Sclerosis Quality of Life-54 (N = 6).
For secondary-progressive MS, symptom-specific PRO instruments were used to measure:
- Mental disorders (9 types of instruments used, 22 studies); of these, depression was the most often measured condition (in 21 studies)
- Fatigue (4 types of instruments used; 10 studies)
- Physical activity (2 types of instruments used; 3 studies).
Overall, MS-specific instruments are the most common PRO instruments used in patients with secondary-progressive MS, with MSIS-29 as the most frequently used instrument in secondary-progressive MS-only studies, Ms Watson noted.
Mental disorders, fatigue, and physical activity were the most frequently measured symptoms captured by the symptom-specific PRO instruments that were identified by the literature review.
“Disease- or symptom-specific measures may be most relevant and meaningful to secondary-progressive MS patients, as these evaluate physical and psychological impact, as well as fatigue,” Ms Watson said.
The majority of the studies did not report the reliability and/or validity of the PRO instruments used. Furthermore, Ms Watson indicated that information on the psychometric properties of PROs was lacking in secondary-progressive MS.
“In the study, we found there was a lack of consistency among the instruments, even when measuring similar outcomes,” she said. “This suggests that additional research is needed to determine which instrument has the best measurement properties in the secondary-progressive MS population using psychometric testing.”