Background:

Hereditary transthyretin amyloidosis (ATTRv) should be considered in patients diagnosed with intravenous immunoglobulin (IVIg)-resistant chronic inflammatory demyelinating polyradiculoneuropathy (IVIg-NR CIDP). In this 1-year long, retrospective, multicentric study, an online questionnaire was sent to 1100 French healthcare professionals (HCPs) investigating: (i) how many IVIg-NR CIDP patients they followed; (ii) how many IVIg-NR CIDP patients had undergone TTR gene analysis; and (iii) how many IVIg-NR CIDP patients were eventually diagnosed with ATTRv. The questionnaire was sent every 3 months for 1 year and contained information on ATTRv clinical manifestations and diagnosis.

Methods:

Study design and study population
This retrospective study was carried out over a 1-year period between December 2020 and December 2021.

An online questionnaire (Appendix) was sent to 1100 HCPs across France with either a private or public practice. These HCPs were selected as they care for the majority of patients with CIDP in France. The HCPs were recruited by the independent company EXAFIELD, which specializes in the recruitment of clinical personnel for market research. All participants were remunerated for taking part in the study.

The HCPs were contacted by telephone and after validation of the qualification criteria, a secure connection link was sent by e-mail to the respondent to answer the questionnaire. The HCPs were asked a number of questions including how they managed and diagnosed their CIDP patients, how many patients with suspected CIDP they had, how many patients were treated with IVIg and were IVIg-NR, how many had undergone TTR gene analysis, and how many had tested positive (Appendix). IVIg-NR was defined as no response to IVIg after 3–4 months of treatment. Only patients with probable or definite CIDP using the 2010 EFNS/PNS diagnostic criteria [17] were included in the survey. The questionnaires were sent to the participants every 3 months for 1 year. The questionnaires were identical in each of the four waves of the survey.

The aim of the study was to determine the percentage of patients with suspected CIDP who were IVIg-NR and subsequently diagnosed with ATTRv.

Results:

One-hundred and ten (10%) HCPs responded. A total of 2131 patients with CIDP were identified, including 315 (22.1%) with IVIg-NR CIDP. TTR gene analysis was performed in 144 patients and was positive in 43 cases (29.9%).

Conclusions:

This study demonstrates that ATTRv should be investigated systematically in patients diagnosed with IVIg-NR CIDP. HCP-directed information campaigns are useful for modifying diagnostic practices.