Charting the Incidence and Prevalence of CIDP in the U.S.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) remains an elusive adversary in the neurological landscape, with its true incidence and prevalence in the United States still largely under-documented. This paucity of contemporary epidemiological data impedes the development of targeted therapies and patient care strategies. A new retrospective claims data analysis aimed to bridge this knowledge gap by assessing CIDP’s incidence and prevalence and offering a detailed portrayal of the patient demographics within the U.S.

Leveraging extensive closed claims data from 2016 to 2020, the study sought to identify individuals with CIDP by utilizing ICD-10 coding and continuous enrollment criteria. By excluding the pandemic-impacted year of 2020 to maintain consistency, the study aimed to provide a less distorted view of CIDP’s epidemiology.

The study, led by Joel Arackal, PharmD, a health outcomes researcher at the University of Health Sciences & Pharmacy in St. Louis, was a retrospective analysis utilizingclaims data covering a cross-section of nearly 170 million patients. The study authors identified patients with CIDP by the presence of at least two claims with CIDP-specific ICD-10 codes (G61.81) spaced at least 30 days apart. Their findings were presented at the American Academy of Neurology 2024 meeting in Denver.

For the incidence cohort, adults ages 18 and over with continuous enrollment throughout 2018 and 2019 were included, provided they had no CIDP diagnosis prior to 2018. The incidence rate was then calculated based on this cohort, adjusted for age and gender according to U.S. census data. The prevalence cohort was identified from those continuously enrolled in 2019 and, similarly, the prevalence rate was determined and adjusted using census benchmarks.

Arackal and colleagues found that the raw CIDP incidence rate among U.S. adults was 3.6 per 100,000 persons, with a consistent adjusted rate after factoring in age and gender distribution. Notably, the incidence rates showed a marked increase in individuals ages 55 and above—peaking at 7.7 per 100,000 individuals at ages 75-84 years—with higher rates observed in men than women.

In terms of prevalence, the raw rate was 14.0 per 100,000 persons, with an adjusted rate of 18.0 per 100,000, indicating a slightly higher epidemiologic burden than previously estimated in older data sets. Based on the adjusted incidence and prevalence rates observed in the study, an estimated 58,405 individuals were living with CIDP in the U.S. in 2019. As with incidence, the prevalence of CIDP also increased with age and was more pronounced in males over 55 years old, again peaking at ages 75-84 years (51.3).

The demographic analysis revealed an almost equal male-to-female ratio across both incident and prevalent cohorts. The median age was slightly higher in men, with hypertension emerging as the most common comorbidity, affecting more than half of the CIDP population. The researchers noted that the profiles detailed in the study are important to understanding the burden of CIDP and may help in tailoring patient-specific management approaches.

Understanding the treatment utilization patterns in CIDP patients provides critical insights into the management approaches and their alignment with current clinical guidelines. According to the study by Arackal et al, a significant proportion of the CIDP patient population receives active treatment, with steroids being the most commonly used medication. In the incident cohort, approximately 79.0% of treated patients received a steroid, while in the prevalent cohort, this number was slightly lower at 69.8%.

The use of immunoglobulin was also prominent, with 52.9% of treated patients in the incident cohort and 54.7% in the prevalent cohort receiving this therapy. This highlights the reliance on immunoglobulins as a cornerstone in CIDP management, reflecting its efficacy in improving neurological function and reducing disease activity. Biologics, including rituximab, were prescribed to a smaller segment of the population, suggesting selective use based on patient-specific factors such as disease severity or prior treatment responses.

Other immunosuppressants, such as azathioprine, mycophenolate, and methotrexate, were utilized less frequently, indicating their role as adjunct or alternative therapies in cases where standard treatment protocols may not be effective or well-tolerated. The data showed that 13.5% of the prevalent cohort was treated with immunosuppressants, slightly higher than the 8.3% in the incident cohort, which the researchers suggested may reflect the progression to more aggressive treatments as the disease advances or persists.

Plasmapheresis, a treatment used to remove harmful antibodies from the blood, was employed in a smaller fraction of patients: 5.7% in the incident cohort and 3.1% in the prevalent cohort. This treatment’s utilization underscores its role in more severe cases or in those who do not respond adequately to pharmacological treatments.

Overall, the treatment utilization data from the study not only reflects the diversity of the therapeutic landscape in CIDP but also the tailored approaches used in managing a disease marked by significant heterogeneity in clinical presentation and progression.

The researchers noted that these data may aid healthcare providers in optimizing treatment strategies to enhance patient outcomes and quality of life, and highlighted several important implications for clinical practice and healthcare policy. For instance:

• The increasing rates of incidence and prevalence with age underscore the need for heightened awareness and early diagnostic interventions, particularly in older populations who may experience more severe disease progression and associated disabilities.
• The balanced gender distribution suggests that both men and women are equally affected by CIDP.
• The prominence of hypertension and other comorbid conditions in the CIDP population calls for a holistic approach to patient management, where treating physicians consider the full spectrum of patient health to optimize outcomes.
• Treatment utilization patterns reveal a strong reliance on steroids and immunoglobulins, aligning with current treatment guidelines that recommend these therapies as first-line treatments due to their effectiveness in reducing disease activity and improving quality of life. However, the use of more aggressive treatments like biologics and plasmapheresis in smaller patient subsets highlights the need for individualized treatment plans, particularly for those who do not respond to conventional therapies.

The study’s findings also point to potential areas for improvement in the management of CIDP. For instance, the relatively lower use of newer biologic therapies and immunosuppressants may indicate a need for further education and research into their efficacy and safety profiles in different patient subsets. Additionally, the healthcare system may benefit from increased funding and resources to support the adoption of these potentially life-altering treatments.

The researchers recommended that future studies aim to explore the long-term outcomes of various treatment regimens and their impact on patient quality of life, to provide a deeper understanding that could lead to more effective and personalized therapeutic approaches.