Rare Disease Report

ERTs Reduce Risk for Wheelchair Dependency in Adult Pompe Patients

MAY 23, 2018
Mathew Shanley
Can enzyme replacement therapies (ERTs) reduce the risk for wheelchair dependency in the adult Pompe disease patient population? According to recent results from an ongoing survey, the answer is “yes.”

Findings from the survey were published by the Orphanet Journal of Rare Diseases this week in an article titled, “Enzyme replacement therapy reduces the risk for wheelchair dependency in adult Pompe patients.” In it, study authors Jan C. van der Meijden and colleagues from the Erasmus MC University Medical Center in the Netherlands investigate results from the IPA/Erasmus MC Pompe survey. The prospective international examination was designed with the intention to investigate whether ERT can reduce patients’ risk of needing either a wheelchair, respirator, or both.

While the findings could not demonstrate the effect of ERT on respiratory support, they were consistent with historical data that has shown the positive clinical benefits of the therapeutic option on motor outcomes.

Data were collected annually between 2002 and 2016, and patients who were already using a wheelchair or respirator were excluded in addition to patients who had incomplete information on the events or disease duration.

Overall, 458 patients participated in the survey, and inclusion criteria for evaluating the risk of wheelchair use was met by 189 patients between the ages of 18 years and 75 years with a median age of 47 years. Time-dependent Cox proportional hazard models were utilized to calculate the effect of ERT on the risk of using a wheelchair or respiratory support, and models were developed separately for both outcomes.

During follow-up, 66.6% of participants (n=126) started ERT. Of those who were administered ERT, 12.7% (n=66) became wheelchair dependent over 1,120 person-years of follow-up (median 5 years). Comparatively, of the 63 participants who were not administered ERT, 47.6% (n=30) became wheelchair dependent in the same median follow-up period. After adjustment for disease duration, sex, and country, it was proven that ERT reduced the risk for wheelchair use (HR 0.36; 95% CI 0.17–0.75).

For analyses of respirator use, 177 patients met the inclusion criteria (median age 46 years; range 18–73). Over 1,190 person-years of follow-up (median 6 years), 71% (n=125) of patients were treated, and 27.1% (n=48) started respiratory support, 15.8% (n=28) of whom received ERT. No association between ERT and the risk for respirator use was found.

Patients are continually included into the open cohort IPA survey. Since its initiation, it has been shown to be an accurate reflection of the clinical spectrum of adult patients with Pompe disease. While some bias could potentially have occurred as patients become lost to follow-up due to the study duration, bias has been mostly minimized through the time dependent nature of the analysis as the same patient could contribute to both the treated and untreated period.

“The difference between being able to walk and needing a wheelchair is very tangible, and ERT’s reduction of the risk for becoming wheelchair dependent is an important improvement,” the study authors concluded. “Nevertheless, a proportion of treated patients still become wheelchair dependent at some point in their life. Hence, while ERT shows positive clinical effects in adult patients with Pompe disease, we also conclude that there is still room for improvement.”

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References:
1. van der Meijden JC, et al. Enzyme replacement therapy reduces the risk for wheelchair dependency. Orphanet Journal of Rare Diseases. 2018;13:82. doi: 0.1186/s13023-018-0824-4.

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