F508del genotype in endoscopic sinus surgery: do differences in outcomes exist between genotypic subgroups?

Background: The impact of endoscopic sinus surgery (ESS) on pulmonary function in cystic fibrosis (CF) patients with chronic rhinosinusitis remains unclear, as studies have demonstrated conflicting results. To date, no study has looked specifically at the impact of CF genotype on lung function after ESS. In this study, we reviewed changes in pulmonary function test (PFT) results after ESS in F508del homozygotes and heterozygotes. Methods: The charts of 25 patients with CF without prior lung transplant, who underwent ESS performed by the same surgeon between the period of July 2005 to July 2015, were retrospectively reviewed. Data including genotype and PFT results were collected. Patients were grouped based on genotype. Pre- and postoperative PFTs were compared. Results: Some differences in PFT outcomes after ESS could be seen on subgroup analyses. For example, when considered as a whole group, the overall cohort showed a significant improvement from preoperative FEV₁ levels at 6 months after surgery (p = 0.0127). Interestingly, on subgroup analysis, the heterozygous group saw significant improvements from preoperative FEV₁ levels at 6 and 12 months (p = 0.0155 and p = 0.0333, respectively). No significant improvements were seen from “baseline” FEV₁ in either group at any timepoint. Conclusion: Prior studies investigating the impact of ESS on pulmonary function in CF patients have shown conflicting results. To our knowledge, those earlier udies did not separate and compare different genotypes, which may have introduced heterogeneity in their patient populations. Our study suggests that grouping CF patients more strictly according to genotype or disease severity when investigating outcomes may reveal differences among various subgroups.