Physical impairments that worsen with disease progression are the main contributors to a poor health-related quality of life among people with Friedreich’s ataxia (FA), according to a recent study.
Data also showed that quality of life measures effectively reflected disease progression in FA patients. That suggests they could be used to assess treatment responses in future clinical trials, the researchers said.
The study, “Health related quality of life in Friedreich Ataxia in a large heterogeneous cohort,” was published in the Journal of the Neurological Sciences.
FA is a rare, inherited, progressive disease of the nerves and muscles that affects a person’s coordination, muscle strength, walking abilities, vision, hearing, and speech. Given its symptoms, FA is considered to have a major negative impact on health-related quality of life, known as HRQOL.
HRQOL tools include measures of general aspects common to many diseases — including the self-reported 36-Item Short Form Health Survey (SF-36) — and disease-specific symptom questionnaires, such as those evaluating bladder control, visual impairment, pain effects, and fatigue.
These measures can be used not only to assess the natural impact of the disease on quality of life over time, but also to help evaluate treatment responses through clinically meaningful improvements in HRQOL.
So far, most studies on the quality of life of people with FA have involved a small number of patients or followed them for a short period of time. Since clinical trials in FA are typically global and may involve long-term assessments, HRQOL monitoring in FA patients may require a global, larger natural history group of patients with a longer follow-up period, scientists say.
Now, with support from the Friedreich Ataxia Research Alliance, an international group of researchers set out to evaluate the HRQOL in a large group of FA patients who were followed for up to 15 years. The team also analyzed potential links between HRQOL and disease features, including age at onset, duration, and severity.
Their work was part of the Friedreich’s Ataxia Clinical Outcomes Measure Study (FACOMS) (NCT03090789), a multicenter natural history study aimed at providing a framework for facilitating therapeutic interventions, including the development of relevant clinical measures for FA patients.
Quality of life among the participants was assessed at their entry into the study and over time with the generic SF-36 and symptom-specific questionnaires, including the Pain Effects Scale, the Bladder Control Scale, the Modified Fatigue Impairment Scale, and the Impact of Visual Impairment Scale.
The SF-36 analyzes eight domains, or areas, that influence HRQOL, with higher scores reflecting better quality of life. These domains include physical functioning, role limitations related to physical problems, role limitations related to emotional problems, bodily pain, emotional well-being, social functioning, energy/fatigue, and general health.
A total of 651 patients — 329 women and 322 men — completed the SF-36, while 805, comprising 408 women and 397 men, responded to symptom-specific scales. The participants were, on average, young adults with a mean age of 32.4, who had been living with the disease for about 16 years.
The results showed that among SF-36 domains, physical function had the lowest scores — ones much lower compared with those reported in other studies for people without FA — whereas emotional well-being had the highest scores.
Lower physical function scores were associated with older age and a more severe disease, while age and disease duration predicted the scores of the other domains.
Considerable reductions over time in SF-36 domains were only observed in the physical function and physical-related role limitation scores. In addition, the pattern and rate of change in these domains were similar across groups with different ages of onset, highlighting the consistent impact of the disease, regardless of when it first developed.
Similar trends and associations were found for symptom-specific scales, with symptoms worsening over time, particularly those related to vision and bladder control. The results also showed that symptoms were associated with disease duration, and predicted by disease severity and age.
“The SF-36 and symptom specific scales capture dysfunction in [FA] in a manner that reflects disease status,” the researchers said.
The team noted that these findings suggest that physical-related scales better reflect FA progression, which depends on both time and disease severity.
“With almost 10 times as many [patients] as previous studies and a duration of study on single [patients] of up to 15 years, the results provide a map that may be useful in contexts outside clinical trials,” they said. “More detailed analysis … may allow identification of results that can be useful in intervention trials.”
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