Background
Elexacaftor/tezacaftor/ivacaftor (ETI) has revolutionized cystic fibrosis (CF) treatment. However, previous research has demonstrated profound global disparities in diagnosis and treatment access. If unaddressed, these threaten to widen existing health inequities. Therefore, in this analysis we aimed to reappraise gaps and evaluate progress in diagnosis and treatment equity in high-income (HIC) versus low- and middle-income countries (LMICs).

Methods
Estimates of the global CF population were made in 158 countries using patient registries, systematic literature searches, and an international survey of 14 CF experts. Estimates of the global burden of undiagnosed CF were made using epidemiological studies identified in literature searches and registry coverage data. The proportion of people receiving ETI was estimated using publicly available revenue data and a survey of 23 national drug pricing databases.

Results
188,336 (163,421–209,204) people are estimated to have CF in 96 countries. Of these, 112,955 (60%) were diagnosed and 51,322 (27%) received ETI. The undiagnosed patient burden is estimated to be 75,381 people, with 82% in LMICs. ETI is reimbursed in 35 HICs, but only one LMIC. Four years after approval, there are 14,911 people diagnosed with CF who live in a country where ETI is inaccessible. This increases to 76,199 when including the estimated undiagnosed population.

Conclusions
Equitable access to CFTR modulators must become a top priority for the international CF community. ETI costs up to $322,000 per year but could be manufactured for $5000 to allow access under a voluntary license. Given the extent of disparities, other mechanisms to improve access that circumvent the manufacturer should also be considered.