Titin antibody, hospitalizations linked in non-thymoma MG
Researchers urge attention to patients positive for antibody
The presence of antibodies targeting titin, a type of muscle protein, in patients with myasthenia gravis (MG) not associated with a thymus tumor is related to more frequent hospitalizations, according to a study in China.
Frequent hospitalizations hurt quality of life and mental health for people with MG, and “may place a financial burden on patients and families,” the researchers wrote. “Therefore, for titin antibody-positive MG patients, special attention needs to be paid to the severity of their condition, the management of comorbidities, and support for mental health and quality of life so as to reduce frequent hospitalizations and improve the overall condition of patients,” they wrote.
The study, “Titin Antibody Is Linked to Increased Hospitalization Rates in Nonthymoma Myasthenia Gravis in Central China,” was published in Acta Neurologica Scandinavia.
MG is an autoimmune disease caused by autoantibodies that target proteins at the neuromuscular junction, the site where nerve and muscle cells communicate to coordinate voluntary movements. The disease’s main symptoms include muscle weakness and fatigue. Patients sometimes experience periods when symptoms worsen, resulting in greater disability.
In 80%-85% of MG patients, autoantibodies target acetylcholine receptors (AChRs) in muscle cells. Other antibodies have also been identified, including some targeting proteins found inside muscle cells. Those include titin, a large, structural protein that’s crucial for muscle contraction.
Titin antibody presence linked to disease severity
Anti-titin antibodies are present in 20%-30% of MG patients with anti-AChR antibodies, more frequently in those with thymoma-associated or late-onset disease. Thymoma is a type of tumor in the thymus gland that’s sometimes seen in people with MG.
Previous studies have linked the presence of anti-titin antibodies with MG severity and poor disease outcomes.
Researchers in China assessed the frequency of hospitalizations and emergency department visits, as well as treatment and clinical outcomes in patients with non-thymoma MG, with or without anti-titin antibodies.
The team evaluated the medical records of patients with non-thymoma MG who had enrolled in the Zhengzhou University MG biobank from January 2017 to July 2022.
Of the 170 patients evaluated, 67 (39.4%) had anti-titin antibodies and 103 (60.6%) did not. Age at disease onset was similar in both groups, as were the proportion of male and female patients and levels of anti-AChR antibodies.
The need for rescue therapy to effectively manage episodes of symptom worsening was significantly higher in the titin-positive group (10.4% vs. 2.9%). There were no significant differences between the two groups regarding maintenance therapy.
There were 282 hospitalizations and nine emergency department visits during the study period. The main reasons for hospitalization included symptom worsening (98.2%), followed by routine evaluation and adjustment of medication (1.8%). Emergency department visits were mainly prompted by difficulty breathing or chest discomfort (55.6%) and bulbar symptoms, or those involving the face and neck (33.3%).
Titin-positive patients accounted for a significantly higher proportion of MG-related hospitalizations than titin-negative patients (85.1% vs. 63.1%) and multiple hospitalizations (59.7% vs. 34%). There were no differences between the two groups regarding the proportion of annual MG-related ED visits.
“This suggests that titin antibody-positive patients have a clinically more severe and difficult-to-control disease process and, as a result, require frequent hospitalizations,” the researchers wrote.
Statistical analyses also indicated that patients with anti-titin antibodies were almost three times more likely to require multiple hospitalizations than titin-negative patients.
“In patients with [non-thymoma MG], titin antibodies were associated with more frequent hospitalizations,” the researchers wrote. “Therefore, titin antibody levels may serve as a clinical indicator for treating patients with nonthymoma-related MG.”
The team noted that further, larger studies are needed to determine whether titin antibody levels may be used to define personalized treatments for patients.
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