Impact of interruption of CFTR modulator therapies

•CFTR modulators are crucial for patients with cystic fibrosis.•High costs of drugs pose challenges in accessing them, in low/middle-income nations.•Patients may experience disruptions in the availability of medications.•After cessation of treatment, FEV1 and BMI z-scores exhibite a significant decline.•Treatment continuation and avoiding interruptions is important for eligible patients. Novel drug therapy targeting the defective cystic fibrosis transmembrane conductance regulator protein has the potential to significantly enhance the quality of life for numerous patients with cystic fibrosis. However, in some countries social insurance does not pay for modulators because these drugs are extremely expensive. This study sought to understand the impact on the health of children whose modulator treatments were interrupted because of legal procedures and delivery processes. Our study identified that the significant increase in percent-predicted forced expiratory volume levels (FEV1) and BMI z-score values associated with modulator therapies decreased sharply with their discontinuation. Significant worsening in FEV1, BMI z-scores, and BW z-scores were detected in the first follow-up visit after therapy discontinuation within 1 month. Eight patients had a reduction of FEV1 of more than 10%. The findings suggest that modulatory treatment continuation is important, and it is crucial that treatment is not interrupted.