Epidemiologic Study of Cystic Fibrosis: 25 years of observational research.

The Epidemiologic Study of Cystic Fibrosis (ESCF) was a prospective observational study of over 32,000 people with cystic fibrosis (CF) from 250 clinical care sites in North America from 1994 to 2005. Begun as a pharmacovigilance study in connection with the approval of dornase alfa in 1993, ESCF was open to all people with CF treated at any participating site in the United States or Canada. In addition to obtaining safety and effectiveness data on dornase alfa, ESCF collected encounter-based data to characterize the natural history and management of CF with a special focus on lung disease. During the study, 32,178 patients reported at least one encounter, contributing 869,136 encounters, 622,592 pulmonary function tests, 432,896 cultures, and 118,563 pulmonary exacerbations treated with intravenous antibiotics. Although ESCF data collection concluded in 2005, through a collaboration with the U.S. Cystic Fibrosis Foundation Patient Registry, additional follow-up data through 2017 was available for two-thirds of patients. This allowed for updating of CF genotype and survival information. Fifty-six peer-reviewed publications (cited over 3600 times) resulted from this study. In this manuscript we summarize the published ESCF manuscripts in thematic groups with key study findings and brief comments, and speculate on how ESCF findings will inform future data registries and patient care practices.

Lung function changes before and after pulmonary exacerbation antimicrobial treatment in cystic fibrosis.

BACKGROUND: In cystic fibrosis, observation of a lung function drop (as percent predicted forced expiratory volume in 1 s [FEV1 ]; ppFEV1 ) frequently precedes pulmonary exacerbation (PEx) diagnosis. Recovery of ppFEV1 to a previous "baseline" is commonly used to assess antimicrobial treatment response. However, not all diagnosed PEx are associated with a ppFEV1 drop, and it is unclear whether these are a different type of PEx from those associated with a ppFEV1 drop. METHODS: We analyzed pre- and posttreatment ppFEV1 for PEx recorded in the Epidemiologic Study of Cystic Fibrosis from 2003 through 2005. Baseline, pretreatment, and follow-up ppFEV1 were the best recorded within 12-months pre-PEx, the lowest recorded -30 to +3 days of treatment, and the best recorded during 6-month follow-up, respectively. Logistic regression models for return of ppFEV1 to baseline during follow-up were developed separately for PEx with ≥10%, <10%, and no ppFEV1 drop before treatment. RESULTS: Of 15 147 PEx, 10 166 (67.1%), 3479 (23.0%), and 1502 (9.9%) presented with a ≥10%, <10%, or no ppFEV1 drop at diagnosis, respectively. 19.5%, 35.2%, and 65.6% of PEx, respectively, had follow-up ppFEV1 equal to or exceeding baseline; overall 27.7% of all PEx treatments resulted in complete recovery of baseline ppFEV1 . Significant predictors of ppFEV1 recovery at follow-up were younger patient age, absence of Aspergillus, lower baseline ppFEV1 , fewer visits during the baseline, lower frequency of prior-year PEx, shorter elapsed time from baseline measure to treatment, smaller relative ppFEV1 drop before treatment, and non intravenous (ie, oral or inhaled antibiotic) treatment. PEx with ≥10%, <10%, and no ppFEV1 drop before treatment had only modest differences in covariate odds ratios associated with complete ppFEV1 recovery. CONCLUSIONS: Among the 10% of PEx presenting with no apparent ppFEV1 drop, more than one-third resulted in a decreased ppFEV1 during follow-up. Risk factors for this outcome were the same as those associated with lack of ppFEV1 recovery among PEx with pretreatment ppFEV1 drops. These results suggest that inherent FEV1 variability, baseline and follow-up sampling methodologies, ppFEV1 regression to the mean, and underlying lung disease progression complicate this approach for assessing effects of PEx and treatment response.

Pulmonary exacerbations and acute declines in lung function in patients with cystic fibrosis.

BACKGROUND: Patients with cystic fibrosis (CF) who experience acute declines in percent predicted FEV1 (ppFEV1 decreased ≥10% relative to baseline) are often not treated with antibiotics for pulmonary exacerbations (PEx), whereas other patients are treated even when they have not experienced a decline in lung function. METHODS: We analyzed 2 patient cohorts using 3 years of Epidemiologic Study of CF data. Cohort 1 (12,837 patients) experienced a ≥10% acute decline in ppFEV1 (n = 22,898) and Cohort 2 (10,416 patients) had a clinician-diagnosed PEx (n = 20,731). RESULTS: 70.7% of ≥10% decline events were treated with antibiotics; with intravenous antibiotics used 67.1% of the time. 32.0% of clinician-diagnosed PEx declined <10%; with intravenous antibiotics used 36.9% of the time. CONCLUSIONS: A clinician's decision to diagnose a PEx and treat with antibiotics often is not defined by measured lung function: a ≥10% FEV1 decline is not considered an absolute indication of a PEx and the lack of a decline does not contraindicate a PEx. Clinicians appear to use the history of prior PEx plus other variables as factors for diagnosing PEx.

Recovery of lung function following a pulmonary exacerbation in patients with cystic fibrosis and the G551D-CFTR mutation treated with ivacaftor.

BACKGROUND: Pulmonary exacerbations (PEx) are associated with acute loss of lung function that is often not recovered after treatment. We investigated lung function recovery following PEx for ivacaftor- and placebo-treated subjects. METHODS: Short- and long-term pulmonary function recovery data after PEx were summarized from a placebo-controlled trial in 161 cystic fibrosis patients≥12years old with the G551D-CFTR mutation (NCT00909532). Short-term recovery was measured 2 to 8weeks after treatment, and long-term recovery was determined at the end-of-study, both compared with baseline measured just prior to the PEx. RESULTS: Fewer patients receiving ivacaftor experienced a PEx than patients receiving placebo (33.7% vs. 56.4%; P=0.004) and had a lower adjusted incidence rate of PEx (0.589 vs. 1.382; P<0.001). The proportion of PEx followed by full short-term recovery of percent predicted forced expiratory volume in 1s was similar (ivacaftor vs. placebo, 57.1% vs. 53.7), as was the proportion of patients having long-term recovery (46.4% vs. 47.7%). CONCLUSIONS: Ivacaftor treatment reduces the frequency of PEx but does not improve on the rate of complete lung function recovery after PEx when compared with placebo.

Lung function decline is delayed but not decreased in patients with cystic fibrosis and the R117H gene mutation.

BACKGROUND: Patients with cystic fibrosis (CF) experience variable lung disease phenotypes. The R117H mutation is often associated with preserved lung function. Our objective was to compare the rate of lung function decline in patients with the R117H mutation and patients homozygous for the F508del mutation. METHODS: Rate of decline in percentage-of-predicted FEV1 (ppFEV1) was analyzed using the 2006-2010 US CF Foundation Patient Registry. RESULTS: 4-year rate of decline was slower in 156 R117H patients compared with 6251 F508del patients (-0.61 vs -2.03 ppFEV1/year, P<0.001). Rates of decline in children were slower in R117H vs F508del patients (6-12-year-olds: +0.73 vs -1.91 ppFEV1/year, P<0.001 and 13-17-year-olds: -1.55 vs -2.66 ppFEV1/year, P=0.046), whereas rates in adults were not significantly different (18-24-year-olds: -1.52 vs -2.12, P=0.26 and ≥25-year-olds: -1.17 vs -1.40, P=0.33). CONCLUSIONS: These findings are consistent with a delayed onset, but ultimately similar progression, of lung disease in R117H compared with homozygous F508del patients.

Comparison of FEV1 reference equations for evaluating a cystic fibrosis therapeutic intervention.

OBJECTIVES: The Global Lung Function Initiative (GLI, 2012) developed reference equations for forced expiratory volume in 1 s (FEV1 ). Previous equations were developed by groups led by Knudson (1983), Wang (1993), Hankinson (1999), and Stanojevic (2008).1,2,4,6 We assessed how different prediction equations affect the conclusions from a therapeutic intervention study that evaluated the rate of percent predicted FEV1 (ppFEV1 ) decline. METHODOLOGY: Using data from the Epidemiologic Study of cystic fibrosis (CF), we re-analyzed our previous study evaluating the relationship of dornase alfa (DA) use with ppFEV1 using the Knudson, Wang & Hankinson, Stanojevic, and GLI equations. The change in intercept and change in slope of ppFEV1 from a 2-year pre-index period and 2-year post-index period were compared between the treated (N = 2483) and comparator groups (N = 6992, from 4110 unique patients). RESULTS: Change in intercept for the comparator group was similar across equations except that Wang & Hankinson values were more negative. The difference in change in intercept between the DA and comparator groups ranged from 3.38 to 4.02% predicted. The change in slope for the comparator group ranged from -0.58 to +0.30 ppFEV1 /year, but the difference in change in slope between the DA and comparator groups was in a narrower range from +0.53 to +0.89 ppFEV1 /year. CONCLUSIONS: Although individual patient results are impacted by the choice of reference equations, the study conclusions from this evaluation of a therapeutic intervention were minimally affected. GLI equations are recommended for future studies, but prior results based on other equations should be accepted as reliable.

Strengthening care teams to improve adherence in cystic fibrosis: a qualitative practice assessment and quality improvement initiative.

BACKGROUND: Treatment regimens for patients with cystic fibrosis (CF) are complex, time consuming, and burdensome, and adherence to CF treatment is suboptimal. CF care teams play a critical role in supporting patients' chronic self-management skills, but there is no uniform method for assessing patients' adherence to treatment or standard interventions to help patients improve when necessary. METHODS: Between May 2015 and March 2016, care team members from 10 CF centers in the USA participated in a practice assessment and quality improvement (QI) initiative. The intervention included a baseline practice assessment survey, personalized continuing medical education (CME)-certified Webconferences with expert study faculty, targeted reinforcement of key practice points, and follow-up online survey and telephone interviews to evaluate the benefits and limitations of the intervention. RESULTS: Responses to the baseline practice assessment survey were received from 50 multidisciplinary care team members representing 10 CF centers. Primary barriers to adherence-related aspects of care in their clinics were motivating patients and caregivers to improve adherence and obtaining accurate information about adherence from patients. At the conclusion of the initiative, participants reported improvements in communication within their care team, implementation of new approaches to asking about adherence, and a renewed commitment to asking patients and caregivers about adherence at each clinic visit. CONCLUSION: Structured QI interventions that bring multidisciplinary care teams together to reflect on clinic processes and elicit objective insights from outside faculty have the potential to improve practice patterns related to the assessment and improvement of patient adherence in CF.

Relationship of Antibiotic Treatment to Recovery after Acute FEV1 Decline in Children with Cystic Fibrosis.

RATIONALE: Children with cystic fibrosis often experience acute declines in lung function. We previously showed that such declines are not always treated with antibiotics, but we did not assess whether treatment improves the likelihood of recovery. OBJECTIVES: To determine whether new antibiotic treatment was associated with recovery from acute FEV1 decline. METHODS: We studied episodes of FEV1 decline (≥10% from baseline) in the Epidemiologic Study of Cystic Fibrosis. Treatments were hospitalization, home intravenous antibiotic, new inhaled oral quinolone, or other oral antibiotic. We used logistic regression to evaluate whether treatment was associated with recovery to baseline or near baseline. RESULTS: Logistic regression of 9,875 patients showed that new antibiotic treatment was associated with an increased likelihood of recovery to 90% of baseline (P < 0.001), especially for hospitalization compared with no new antibiotic (odds ratio [OR], 2.79; 95% confidence interval, 2.41-3.23). All four outpatient treatments were associated with greater likelihood of recovery compared with no treatment (OR, 1.27-1.64). Inpatient treatment was better than outpatient treatment (OR, 1.94; 95% confidence interval, 1.68-2.23). Treatment-type ORs were similar across recovery criteria and levels of baseline lung function. CONCLUSIONS: New antibiotic therapy, and especially inpatient treatment, is associated with greater likelihood of recovery after acute decline in FEV1. Benefits extend across all disease stages and are especially important in patients with high lung function, who are at greatest risk for FEV1 decline.

Frequency and costs of pulmonary exacerbations in patients with cystic fibrosis in the United States.

BACKGROUND: Information is limited regarding the cost of pulmonary exacerbations (PEx) among patients with cystic fibrosis in the United States. METHODS: To examine PEx costs, medical chart data were linked to insurance claims for patients aged ≥6 years who had commercial coverage from a large US health insurer affiliated with Optum during 2008-2013. A PEx was categorized as an episode requiring newly started (1) oral antibiotics (PEx-O) or (2) intravenous (IV) antibiotics and/or inpatient stay (PEx-IV). RESULTS: Among 241 patients, 88.0% had ≥1 PEx (2.9/year) of any type, and 48.1% had ≥1 PEx-IV. Prior PEx-IV was the strongest risk factor for subsequent PEx-IV. The mean cost per episode was $12,784 for PEx of any type and $36,319 for PEx-IV. Patients with worse lung function were more likely to experience a PEx and incurred higher annual PEx-related costs. LIMITATIONS: This was an observational study using a convenience sample of patients with commercial coverage from a large US health insurer whose medical charts were available for abstraction. Results of the study may not be generalizable to individuals with Medicaid coverage and other types of insurance, or to the uninsured. CONCLUSIONS: Most patients experience ≥1 PEx annually, and nearly half require IV antibiotics and/or inpatient stay at considerable cost.

BMI fails to identify poor nutritional status in stunted children with CF.

BACKGROUND: Body mass index (BMI) is currently emphasized for evaluating nutritional status in children with cystic fibrosis (CF). Weight for age (WFA) and height for age (HFA) may get less attention. METHODS: Data from the Epidemiologic Study of Cystic Fibrosis were used to compare patient WFA, HFA, and BMI percentiles for children age 2 to 18years. RESULTS: For children with BMI between the 25th and 50th percentiles, 16.8% had WFA <10th percentile and 26.6% had HFA <10th percentile. CONCLUSIONS: BMI fails to identify a substantial proportion of children with CF who have stunting or potentially poor nutritional status as measured by WFA and/or HFA.

Improving performance in the detection and management of cystic fibrosis-related diabetes in the Mountain West Cystic Fibrosis Consortium.

OBJECTIVE: Cystic fibrosis (CF)-related diabetes (CFRD) is associated with increased morbidity and mortality. Improved detection and management may improve outcomes; however, actual practice falls short of published guidelines. We studied efforts to improve CFRD screening and management in the Mountain West CF Consortium (MWCFC). RESEARCH DESIGN AND METHODS: This is a prospective observational cohort study evaluating quality improvement by accredited CF centers in Arizona, Colorado, New Mexico, and Utah performed between 2002 and 2008. After Institutional Review Board (IRB) approval, centers evaluated adherence with CF Foundation guidelines for CFRD. Each center developed and implemented quality improvement plans to improve both screening and management. Centers were reassessed 1 year later. RESULTS: Initially, each CF center had low adherence with screening recommendations (26.5% of eligible patients) that did not improve during the study. However, patients with confirmed CFRD markedly increased (141 (12% of MWCFC patients) to 224 (17%), p<0.001), and with improved adherence to management guidelines, patients with CFRD had increased weight (56.8-58.9 kg, p<0.001), body mass index (21.1-21.4, p=0.003), and weight-for-age z-score (-1.42 to -0.84, p<0.001). Quality improvement methods were specific to the practice settings of each center but shared the common goal of adhering to CFRD care guidelines. 1 year after implementation, no center significantly differed from any other in level of adherence to guidelines. CONCLUSIONS: Improving adherence with CFRD care guidelines requires substantial effort and may be incompletely successful, particularly for CFRD screening, but the effort may significantly improve patient monitoring and clinically relevant outcomes such as weight.

Healthcare resource utilization associated with ivacaftor use in patients with cystic fibrosis.

OBJECTIVE: Ivacaftor was approved in 2012 to treat patients with cystic fibrosis (CF) with specific CFTR gene mutations. The objective of this analysis was to analyze the impact of ivacaftor on health resource utilization through analysis of claims data. METHODS: Patients diagnosed with CF aged ≥6 years prescribed ivacaftor between January 1, 2012 and July 31, 2014 with ≥12 months of continuous insurance coverage prior to and following the prescription were identified. All-cause and CF-specific healthcare resource utilization during the pre- and post-prescription periods and ivacaftor adherence levels were studied. RESULTS: The 79 identified patients had a mean age of 20.8 years, and 54% were female. The proportion of patients with inpatient admissions (all-cause and CF-related) was significantly higher in the pre index compared to post index period (p ≤ 0.05). Mean ivacaftor medication possession ratio was 0.8 (SD = 0.3), and 73% of patients had a medication possession ratio >0.80. LIMITATIONS: Only a small number of patients met the inclusion criteria. Additionally, claims data may contain errors or inconsistencies and cannot be used to determine if medications were taken as prescribed. CONCLUSIONS: Ivacaftor therapy was associated with significant reductions in hospitalizations along with high rates of adherence to treatment over 12 months.

Forced Expiratory Volume in 1 Second Variability Helps Identify Patients with Cystic Fibrosis at Risk of Greater Loss of Lung Function.

OBJECTIVE: To evaluate several alternative measures of forced expiratory volume in 1 second percent predicted (FEV1 %pred) variability as potential predictors of future FEV1 %pred decline in patients with cystic fibrosis. STUDY DESIGN: We included 13,827 patients age ≥6 years from the Epidemiologic Study of Cystic Fibrosis 1994-2002 with ≥4 FEV1 %pred measurements spanning ≥366 days in both a 2-year baseline period and a 2-year follow-up period. We predicted change from best baseline FEV1 %pred to best follow-up FEV1 %pred and change from baseline to best in the second follow-up year by using multivariable regression stratified by 4 lung-disease stages. We assessed 5 measures of variability (some as deviations from the best and some as deviations from the trend line) both alone and after controlling for demographic and clinical factors and for the slope and level of FEV1 %pred. RESULTS: All 5 measures of FEV1 %pred variability were predictive, but the strongest predictor was median deviation from the best FEV1 %pred in the baseline period. The contribution to explanatory power (R(2)) was substantial and exceeded the total contribution of all other factors excluding the FEV1 %pred rate of decline. Adding the other variability measures provided minimal additional value. CONCLUSIONS: Median deviation from the best FEV1 %pred is a simple metric that markedly improves prediction of FEV1 %pred decline even after the inclusion of demographic and clinical characteristics and the FEV1 %pred rate of decline. The routine calculation of this variability measure could allow clinicians to better identify patients at risk and therefore in need of increased intervention.

Sustained Benefit from ivacaftor demonstrated by combining clinical trial and cystic fibrosis patient registry data.

RATIONALE: In clinical trials, patients with cystic fibrosis and a G551D mutation who received ivacaftor experienced improvements in pulmonary and nutritional outcomes. However, whether these improvements reflect a change in disease trajectory cannot be determined without longer-term analyses with an appropriate comparator population. OBJECTIVES: To examine, over a 3-year period, whether ivacaftor therapy affects pulmonary function and nutritional measures in patients with CF with a G551D mutation compared with patients with CF who are homozygous for the F508del mutation. METHODS: A propensity score was used to match patients with CF greater than or equal to 6 years of age who have a G551D mutation and received ivacaftor in clinical trials for up to 144 weeks with data from patients in the U.S. Cystic Fibrosis Foundation Patient Registry who are homozygous for the F508del mutation. Matching was based on variables including age, sex, weight for age, height for age, body mass index for age, % predicted FEV1, and chronic therapies (dornase alfa, inhaled antibiotics, inhaled and oral corticosteroids). MEASUREMENTS AND MAIN RESULTS: By calculating the annual estimated rate of decline in lung function for G551D patients receiving ivacaftor and comparing it with the rate of decline in lung function for matched F508del control patients, we show that the rate of lung function decline in G551D ivacaftor-treated patients was slower by nearly half. Moreover, treatment with ivacaftor is shown to improve body mass index and weight-for-age z scores for G551D patients over the 3-year analysis period. CONCLUSIONS: These findings suggest that ivacaftor is a disease-modifying therapy for the treatment of cystic fibrosis.

Pulmonary function outcomes for assessing cystic fibrosis care.

BACKGROUND: Assessing cystic fibrosis (CF) patient quality of care requires the choice of an appropriate outcome measure. We looked systematically and in detail at pulmonary function outcomes that potentially reflect clinical practice patterns. METHODS: Epidemiologic Study of Cystic Fibrosis data were used to evaluate six potential outcome variables (2002 best FVC, FEV(1), and FEF(25-75) and rate of decline for each from 2000 to 2002). We ranked CF care sites by outcome measure and then assessed any association with practice patterns and follow-up pulmonary function. RESULTS: Sites ranked in the top quartile had more frequent monitoring, treatment of exacerbations, and use of chronic therapies and oral corticosteroids. The follow-up rate of pulmonary function decline was not predicted by site ranking. CONCLUSIONS: Different pulmonary function outcomes associate slightly differently with practice patterns, although annual FEV(1) is at least as good as any other measure. Current site ranking only moderately predicts future ranking.

Liver involvement in the Hispanic population of North America with cystic fibrosis.

OBJECTIVES: The aim of the present article was to determine the prevalence of liver involvement in Hispanic patients with cystic fibrosis (CF) and identify associations with age and severity of liver involvement. METHODS: We used 1994-2005 Epidemiologic Study of CF data to compare abnormal liver findings between Hispanic and non-Hispanic white patients with CF. RESULTS: Of 30,727 patients with CF, 5015 had liver involvement. Of 1957 Hispanic patients, 20.8% had liver involvement compared with 16.0% of 28,770 non-Hispanic white patients (odds ratio [OR] 1.38, 95% confidence interval [CI] 1.23-1.54). This higher prevalence of liver involvement persisted after adjusting for demographics and meconium ileus and was especially high in the first year of life (adjusted OR 3.14, 95% CI 2.27-4.35). Ten percent of infants with only elevated liver enzymes progressed to more severe liver disease. CONCLUSIONS: The Hispanic population with CF has more liver involvement (both elevated liver enzymes and clinical liver disease) than the non-Hispanic white population with CF, especially during the first year of life.

Clinical use of tobramycin inhalation solution (TOBI®) shows sustained improvement in FEV1 in cystic fibrosis.

OBJECTIVES: Tobramycin inhalation solution (TIS; TOBI®) has improved forced expiratory volume in 1 sec (FEV1 ) in cystic fibrosis (CF) trials. Using data from the Epidemiologic Study of CF (ESCF), we assessed the change in level and trend of FEV1 % predicted (pred) over a 2-year period associated with initiation of TIS during routine clinical practice. METHODS: Patients age 8-38 years and in ESCF for ≥2 years before treatment with TIS as a chronic therapy were selected if they remained on therapy for 2 years, defined as being on TIS for at least 3 months per year (C-TIS group). Comparator intervals age 8-38 years used TIS <10% of the time. For each interval, we estimated the level and trend (rate of decline) in FEV1 % pred before and after the index using a piecewise linear mixed-effects model adjusted for potential confounders. RESULTS: During the 2-year pre-index period the C-TIS group (n = 2,534) had a more rapid decline in FEV1 (-2.49% vs. -1.39% pred/year) and a lower FEV1 at index (62.6% vs. 74.7% pred) than the comparator group (N = 17,656 intervals). After starting chronic TIS, the FEV1 trend line over the 2-year post-index period was higher, but the comparator group's FEV1 was essentially unchanged (difference 2.22, P < 0.001). Change in slope was not different between groups (0.06, P = 0.82). CONCLUSIONS: Initiating chronic TIS therapy in the routine clinical care of patients with CF was associated with improvement in FEV1 % pred but no change in rate of decline, which means that this benefit was sustained over the 2 years studied.

Pulmonary capillaritis in monozygotic twin boys.

Pulmonary hemorrhage can be classified as either proximal or distal (alveolar). Causes of proximal hemorrhage include infection, foreign body aspiration, pulmonary embolus, trauma, vascular malformation, and pulmonary hypertension. Causes of distal or diffuse alveolar hemorrhage are divided by the histologic presence or absence of capillaritis, which is characterized by inflammation of the alveolar interstitium and pulmonary capillary structure. Pulmonary capillaritis is a rare event in children and is associated with higher morbidity and mortality than diffuse alveolar hemorrhage without capillaritis. This is a report of 17-month-old previously healthy monozygotic twins presenting simultaneously with diffuse alveolar hemorrhage, pulmonary capillaritis, and an otherwise negative serologic workup. This suggests a role of genetic predisposition in this rare disease.