CFTR genotype as a predictor of prognosis in cystic fibrosis.
OBJECTIVE
Certain CFTR genotypes are associated with reduced mortality. The accuracy of using CFTR genotype as a predictor of survival and the mechanisms through which CFTR genotype influences survival are unknown.


METHODS
All patients with cystic fibrosis (CF) enrolled in the US Cystic Fibrosis Foundation national registry between 1993 and 2002.


METHODS
We examined the prognostic value of CFTR genotype, grouped into "high-risk" and "low-risk" categories based on the effect of their CFTR genotype on phenotype and protein production.


RESULTS
Clinical and genetic data were available from 15,651 patients with CF. Patients with a high-risk CFTR genotype had a greater than twofold increased risk of death compared to patients with a low-risk CFTR genotype (relative risk, 2.25; 95% confidence interval [CI], 1.77 to 2.84; p < 0.001). This association was partly explained by lung function, nutritional status, pancreatic insufficiency, and Pseudomonas aeruginosa colonization. Of the 1,672 patients who died, median age at death for the high-risk CFTR genotype was 24.2 years (interquartile range, 18.4 to 32.0 years) and for the low-risk CFTR genotype was 37.6 years (interquartile range, 28.8 to 47.9 years; p < 0.001). The positive predictive value of this classification method as a test to identify patients who died before or after their 30th birthday was 69% (95% CI, 67 to 72%) with a negative predictive value of 71% (95% CI, 60 to 80%).


CONCLUSIONS
Grouping patients into high-risk and low-risk CFTR genotype categories is associated with significant differences in survival and median age at death. These differences are not fully explained by lung function, nutritional measures, pancreatic insufficiency, or P aeruginosa colonization. Modest reassurance about the likelihood of a milder than average course can be provided for CF patients with a low-risk CFTR genotype, although it should be acknowledged that substantial phenotypic variability exists.
McKone
Edward F
EF
Division of Pulmonary and Critical Care Medicine and Adult Cystic Fibrosis Center, University of Washington Medical Center, Seattle, WA 98195-6522, USA. emckone@u.washington.edu
Goss
Christopher H
CH
Aitken
Moira L
ML
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003550:Cystic Fibrosis / Q000235:genetics* / Q000401:mortality*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D008168:Lung / Q000382:microbiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011550:Pseudomonas aeruginosa / Q000472:pathogenicity; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate
C505032:CFTR protein, human; D019005:Cystic Fibrosis Transmembrane Conductance Regulator