UBC Theses and Dissertations
Clinical characteristics and predictors of reduced survival for adult-diagnosed cystic fibrosis patients – a population based study Desai, Sameer
Background: Approximately 5-10% of cystic fibrosis (CF) diagnoses are made during adulthood. These patients are a minority, and there is a paucity of literature describing their characteristics and prognosis. The objectives of this study are to describe the clinical characteristics, estimate survival, and identify clinical predictors of reduced survival at the time of diagnosis in adult-diagnosed CF patients. Methods: There were 362 newly diagnosed adult CF (≥18 years) patients from 1990 to 2014 in the Canadian CF Patient Registry. Clinical characteristics were described, the Kaplan-Meier method was employed for 10- and 15-year lung transplant-free survival estimates and multivariable Cox regression analysis was conducted to identify significant predictors of reduced survival at baseline. Adjusted survival curves were used to illustrate the impact of the significant predictors on lung transplant-free survival. Results: The median follow-up time observed was 7.7 years (range: 0.0-23.6) and included 33 deaths and 15 transplants for a total of 48 events in 3,106 patient years (15.5 events per 1,000 PYs). The median age at diagnosis was 34.3 years (range: 18.0-73.8), with the majority presenting with pulmonary and/or gastrointestinal symptoms (70%) and a nearly equal distribution of males and females. During the study period, 15% were diagnosed with CF-related diabetes (CFRD), 35% with pancreatic insufficiency and 50% were culture positive for P. aeruginosa. The most common genotype identified was ∆F508 heterozygous (38%). Lung transplant-free survival was 88% at 10 years and 86% by 15 years. Age at diagnosis (HR: 1.32 per 5-year increase, 95% CI: 1.13-1.54), CFRD (HR: 7.86, 95% CI: 2.09-29.55) and lower lung function (HR: 0.76 per 5% increase, 95% CI: 0.69-0.83) at baseline were significant predictors of reduced survival. In terms of clinical utility, low lung function (FEV1 % predicted < 60%) and CFRD were predictors that impacted lung transplant-free survival substantially. Conclusions: Adult-diagnosed CF patients have a milder phenotype of disease and a better prognosis than previously reported. Older age at diagnosis, lower lung function, and CFRD were important predictors of reduced survival. Adult CF clinicians and other CF caregivers can use this information to educate patients about their prognosis and to guide treatment.
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