Assessing grip strength may be a viable way to optimize intravenous immune globulin (IVIg) treatments in patients with chronic inflammatory demyelinating polyneuropathy (CIDP), suggests results from the small, prospective, observational GRIPPER study presented at the annual meeting of the American Association for Neuromuscular and Electrodiagnostic Medicine in Austin, Tex.
Adequate evidence exists to guide physicians in effective IVIg dosing and frequency and in maintenance therapy, but no evidence-based method exists for determining whether a patient needs to continue therapy, explained Jeffrey A. Allen, MD, an assistant professor of neurology at the University of Minnesota in Minneapolis.
Jeffrey A. Allen, MD
“It turns out that about 40% or so of patients probably get treated with IVIg and other immunotherapy drugs and don’t need treatments. They’re in a stage of remission.”
“It turns out that about 40% or so of patients probably get treated with IVIg and other immunotherapy drugs and don’t need treatments. They’re in a stage of remission,” Dr. Allen said in an interview. “One of the challenges is we don’t have any good biomarker to say which patients have active disease that needs treatment and which ones don’t, or how to follow treatment responses.”
Those decisions currently rely on providers’ clinical impression, but no standards exist for making these decisions, or even how to make them, said Dr. Allen, who presented the research at the meeting.
Grip strength has previously been studied as a marker for following patients with CIDP. Dr. Allen and his colleagues sought to quantify changes in grip strength between IVIg cycles, aiming to use grip strength to determine a patient’s improvement after beginning immunotherapy or to identify patients who relapse after stopping immunotherapy.
They enrolled 25 patients with CIDP, average age 53 years, who were receiving IVIg treatment with dosing frequency of 21-42 days. Patients’ diagnoses of CIDP had to meet the European Federation of Neurological Societies and the Peripheral Nerve Society 2010 criteria and be confirmed by two of three experts. Participants had been diagnosed for an average of 53.5 months and had symptoms for an average of 71.5 months.
Over 6 months, the researchers collected daily grip strength measurements for 94% of total possible days. They considered random day-to-day fluctuations of less than 10% to be noise. They classified patients as high fluctuaters if treatment-related fluctuations occurred during at least one-third of treatment cycles. Those who had treatment-related fluctuations in less than one-third of their cycles were deemed low fluctuaters.
The researchers found that 3-day averaged grip strength peaked 9-12 days after treatment on the right hand and 6-9 days after treatment on the left. Grip strength returned to baseline typically around 18 days after treatment.
The authors concluded that collecting grip strength measurements “is feasible, reliable, and has good validity,” and that averaged changes of 10% or greater appear reliable for identifying treatment-related fluctuations. IgG levels, meanwhile, “are not helpful to guide treatment or to identify treatment responders,” the researchers concluded.
“If somebody clearly has fluctuations between an IVIg cycle, we can conclude … that they’re probably dependent on their immunotherapy” and have active disease, Dr. Allen said. “Then the goal is to use that information to develop some rational approaches to optimizing therapy in individual patients in the clinic setting.”
“If somebody clearly has fluctuations between an IVIg cycle, we can conclude … that they’re probably dependent on their immunotherapy” and have active disease, Dr. Allen said. “Then the goal is to use that information to develop some rational approaches to optimizing therapy in individual patients in the clinic setting.”
No external funding was noted, and Dr. Allen had no disclosures