Lung Function Decline in Cystic Fibrosis: Impact of Data Availability and Modeling Strategies on Clinical Interpretations.

Rationale: Studies estimating the rate of lung function decline in cystic fibrosis have been inconsistent regarding the methods used. How the methodology used impacts the validity of the results and comparability between studies is unknown. Objectives: The Cystic Fibrosis Foundation established a work group whose tasks were to examine the impact of differing approaches to estimating the rate of decline in lung function and to provide analysis guidelines. Methods: We used a natural history cohort of 35,252 individuals with cystic fibrosis aged ⩾6 years in the Cystic Fibrosis Foundation Patient Registry (CFFPR), 2003-2016. Modeling strategies using linear and nonlinear forms of marginal and mixed-effects models, which have previously quantified the rate of forced expiratory volume in 1 second (FEV1) decline (percent predicted per year), were evaluated under clinically relevant scenarios of available lung function data. Scenarios varied by sample size (overall CFFPR, medium-sized cohort of 3,000 subjects, and small-sized cohort of 150), data collection/reporting frequency (encounter, quarterly, and annual), inclusion of FEV1 during pulmonary exacerbation, and follow-up length (<2 yr, 2-5 yr, entire duration). Results: Rate of FEV1 decline estimates (percent predicted per year) differed between linear marginal and mixed-effects models; overall cohort estimates (95% confidence interval) were 1.26 (1.24-1.29) and 1.40 (1.38-1.42), respectively. Marginal models consistently estimated less rapid lung function decline than mixed-effects models across scenarios, except for short-term follow-up (both were ∼1.4). Rate of decline estimates from nonlinear models diverged by age 30. Among mixed-effects models, nonlinear and stochastic terms fit best, except for short-term follow-up (<2 yr). Overall CFFPR analysis from a joint longitudinal-survival model implied that an increase in rate of decline of 1% predicted per year in FEV1 was associated with a 1.52-fold (52%) increase in the hazard of death/lung transplant, but the results exhibited immortal cohort bias. Conclusions: Differences were as high as 0.5% predicted per year between rate of decline estimates, but we found estimates were robust to lung function data availability scenarios, except short-term follow-up and older age ranges. Inconsistencies among previous study results may be attributable to inherent differences in study design, inclusion criteria, or covariate adjustment. Results-based decision points reported herein will support researchers in selecting a strategy to model lung function decline most reflective of nuanced, study-specific goals.

Rate of Lung Function Decline in People with Cystic Fibrosis Having a Residual Function Gene Mutation.

INTRODUCTION: Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Approximately 5% of people with CF have residual function (RF) CFTR mutations that result in partially retained CFTR activity. Published literature on disease trajectory among those with RF mutations is limited. In this retrospective study, we characterized lung function decline across different age groups in CFTR modulator-untreated people with CF heterozygous for F508del and an RF mutation (F/RF). METHODS: Rate of decline in percent predicted forced expiratory volume in 1 s (ppFEV1) was analyzed using data from the US CF Foundation Patient Registry (2006-2014) in F/RF (all), F/RF (excluding R117H), and F508del homozygous (F/F) cohorts. Annual rates of ppFEV1 decline were estimated over 2-year periods based on calendar year. Subgroup analyses by age [6-12 (children), 13-17 (adolescents), 18-24 (young adults), and ≥ 25 years (adults)] were performed. RESULTS: The estimated annualized rate of ppFEV1 decline was - 0.70 percentage points per year (95% CI -1.09, -0.30) in the F/RF (all) cohort (N = 1242) versus -1.91 percentage points per year (95% CI -2.01, -1.80) in the F/F cohort (N = 11,916) [difference, 1.29 percentage points per year (95% CI 0.88, 1.70); P < 0.001]. In the F/RF (all) cohort, all age groups demonstrated lung function decline ranging from -0.30 to -1.38. In the F/RF (excluding R117H) cohort, the rate of decline was -1.05 percentage points per year (95% CI -1.51, -0.60) [difference versus F/F cohort, 0.95 percentage points per year (95% CI 0.48, 1.41; P < 0.001); not statistically significant in children and young adults]. CONCLUSION: Progressive lung function decline was observed in people with F/RF genotypes across all assessed age groups, reinforcing the importance of early intervention and clinical monitoring to preserve lung function in all people with CF.

In people with cystic fibrosis, lung function typically decreases over time and is linked to the severity of the disease. How fast lung function decreases (referred to as the rate of lung function decline) in cystic fibrosis depends on the specific mutations (changes) in the CFTR gene (which causes the disease). Lung function decline has been well studied in some mutation groups, but not many previous studies have looked at lung function decline in people with one copy of the F508del-CFTR mutation (which is the most common CFTR mutation and results in little to no functional CFTR protein) and another CFTR mutation called a residual function mutation (referred to as people with F/RF genotypes). We used data from the US Cystic Fibrosis Foundation Patient Registry (which collects information on the health of people in the USA who have cystic fibrosis), to look at the rate of lung function decline in people with F/RF genotypes. We found that people with cystic fibrosis who have F/RF genotypes experience lung function loss over time. We also found that this lung function loss occurred in people of all ages with F/RF genotypes. This finding supports the importance of early treatment to help prevent lung function loss in all people with cystic fibrosis, including people with F/RF genotypes.

Assessing the impact of sodium oxybate treatment on functioning, productivity, and health-related quality of life in patients with narcolepsy: findings from the Nexus Narcolepsy Registry (waves 1-4).

BACKGROUND: The aim of this study was to evaluate the impact of different therapy regimens, including sodium oxybate (SXB)-containing regimens, on patient-reported outcomes (PROs) in people with narcolepsy. METHODS: Online surveys were used to collect information from persons with narcolepsy in the Nexus Narcolepsy Registry. Surveys contained questionnaires assessing self-reported sleep quality (SQ; via single question), daytime sleepiness and function (Epworth Sleepiness Scale and Functional Outcomes of Sleep Questionnaire), health-related quality of life (HRQoL; 36-Item Short Form Health Survey [SF-36]), work productivity and impairment (Work Productivity and Activity Impairment: Specific Health Problem), and history of injuries or motor vehicle accidents. Treatment with SXB (including monotherapy or combination therapy; SXB group) was compared with non-SXB therapy (No SXB group). The P values presented are nominal, as there are no adjustments for multiplicity. RESULTS: From June 2015 through December 2017, 983 participants completed 1760 surveys. SQ and daytime functioning scores were better in the SXB group compared with the No SXB group (all P < 0.001). HRQoL scores were better for the SXB group compared with the No SXB group for the SF-36 Physical Component (P = 0.016), Mental Component (P < 0.001), and all 8 subscales. Additionally, PROs were better for the SXB group for presenteeism, overall work and activity impairment, and risk of motor vehicle accidents (all P ≤ 0.001). CONCLUSION: Based on participants' self-assessments, treatment regimens with SXB were associated with better outcomes than regimens not containing SXB across many PROs, including SQ, HRQoL, work and activities, and risk of traffic accidents. CLINICALTRIALS. GOV IDENTIFIER: NCT02769780.

The Nexus Narcolepsy Registry: methodology, study population characteristics, and patterns and predictors of narcolepsy diagnosis.

OBJECTIVE/BACKGROUND: The real-world experience of people with narcolepsy is not well understood. PATIENTS/METHODS: The Nexus Narcolepsy Registry (NCT02769780) is a longitudinal, web-based patient registry of self-reported data from adults with physician-diagnosed narcolepsy. Surveys were electronically distributed every 6 months; the current analysis reports registry population demographics, narcolepsy diagnosis journey, and predictors of diagnostic delays. RESULTS: The registry population included in this analysis (N = 1024) was predominantly female (85%) and White (92%), with a mean age of 37.7 years. Most participants had education/training beyond high school (93%). Mean (median) reported ages at narcolepsy symptom onset, first consultation for symptoms, and narcolepsy diagnosis were 18.1 (16), 26.4 (24), and 30.1 (28) years, respectively. A majority (59%) of participants reported ≥1 misdiagnosis, and 29% reported consulting ≥5 physicians before narcolepsy diagnosis. More than half (56%) of participants' first consultations for narcolepsy symptoms were with a general practitioner, whereas the diagnosing clinician was usually a sleep specialist (64%) or neurologist (27%). Pediatric symptom onset was associated with a longer mean interval to first consultation than adult symptom onset (10.7 and 4.6 years, respectively; P < 0.001) and a longer mean interval between first consultation and diagnosis (4.5 and 2.2 years, respectively; P < 0.001). Overall, mean (95% CI) time from symptom onset to diagnosis was 11.8 (11.1-12.5) years. CONCLUSIONS: The Nexus Narcolepsy Registry data indicate that onset of narcolepsy symptoms frequently occurs in childhood or adolescence. In many individuals, the diagnostic process is long and involves multiple physicians and frequent misdiagnosis.

Long-term safety and efficacy of tezacaftor-ivacaftor in individuals with cystic fibrosis aged 12 years or older who are homozygous or heterozygous for Phe508del CFTR (EXTEND): an open-label extension study.

BACKGROUND: Tezacaftor-ivacaftor is an approved cystic fibrosis transmembrane conductance regulator (CFTR) modulator shown to be efficacious and generally safe and well tolerated over 8-24 weeks in phase 3 clinical studies in participants aged 12 years or older with cystic fibrosis homozygous for the Phe508del CFTR mutation (F/F; study 661-106 [EVOLVE]) or heterozygous for the Phe508del CFTR mutation and a residual function mutation (F/RF; study 661-108 [EXPAND]). Longer-term (>24 weeks) safety and efficacy of tezacaftor-ivacaftor has not been assessed in clinical studies. Here, we present results of study 661-110 (EXTEND), a 96-week open-label extension study that assessed long-term safety, tolerability, and efficacy of tezacaftor-ivacaftor in participants aged 12 years or older with cystic fibrosis who were homozygous or heterozygous for the Phe508del CFTR mutation. METHODS: Study 661-110 was a 96-week, phase 3, multicentre, open-label study at 170 clinical research sites in Australia, Europe, Israel, and North America. Participants were aged 12 years or older, had cystic fibrosis, were homozygous or heterozygous for Phe508del CFTR, and completed one of six parent studies of tezacaftor-ivacaftor: studies 661-103, 661-106, 661-107, 661-108, 661-109, and 661-111. Participants received oral tezacaftor 100 mg once daily and oral ivacaftor 150 mg once every 12 h for up to 96 weeks. The primary endpoint was safety and tolerability. Secondary endpoints were changes in lung function, nutritional parameters, and respiratory symptom scores; pulmonary exacerbations; and pharmacokinetic parameters. A post-hoc analysis assessed the rate of lung function decline in F/F participants who received up to 120 weeks of tezacaftor-ivacaftor in studies 661-106 (F/F) and/or 661-110 compared with a matched cohort of CFTR modulator-untreated historical F/F controls from the Cystic Fibrosis Foundation Patient Registry. Primary safety analyses were done in all participants from all six parent studies who received at least one dose of study drug during this study. This study was registered at ClinicalTrials.gov (NCT02565914). FINDINGS: Between Aug 31, 2015, to May 31, 2019, 1044 participants were enrolled in study 661-110 from the six parent studies of whom 1042 participants received at least one dose of study drug and were included in the safety set. 995 (95%) participants had at least one TEAE; 22 (2%) had TEAEs leading to discontinuation; and 351 (34%) had serious TEAEs. No deaths occurred during the treatment-emergent period; after the treatment-emergent period, two deaths occurred, which were both deemed unrelated to study drug. F/F (106/110; n=459) and F/RF (108/110; n=226) participants beginning tezacaftor-ivacaftor in study 661-110 had improvements in efficacy endpoints consistent with parent studies; improvements in lung function and nutritional parameters and reductions in pulmonary exacerbations observed in the tezacaftor-ivacaftor groups in the parent studies were generally maintained in study 661-110 for an additional 96 weeks. Pharmacokinetic parameters were also similar to those in the parent studies. The annualised rate of lung function decline was 61·5% (95% CI 35·8 to 86·1) lower in tezacaftor-ivacaftor-treated F/F participants versus untreated matched historical controls. INTERPRETATION: Tezacaftor-ivacaftor was generally safe, well tolerated, and efficacious for up to 120 weeks, and the safety profile of tezacaftor-ivacaftor in study 661-110 was consistent with cystic fibrosis manifestations and with the safety profiles of the parent studies. The rate of lung function decline was significantly reduced in F/F participants, consistent with cystic fibrosis disease modification. Our results support the clinical benefit of long-term tezacaftor-ivacaftor treatment for people aged 12 years or older with cystic fibrosis with F/F or F/RF genotypes. FUNDING: Vertex Pharmaceuticals Incorporated.

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.

Rapid lung function decline in adults with early-stage cystic fibrosis lung disease.

RATIONALE: The prevalence of adults living with cystic fibrosis (CF) who have early-stage lung disease is increasing. OBJECTIVES: Describe the prevalence and evaluate spirometric risk factors associated with the subgroup of patients with early-stage lung disease and FEV1 decline of ≥5% predicted/year. METHODS: Retrospective cohort study of patients ≥18 years with FEV1% predicted ≥80% included in the US CF Foundation Patient Registry from 2010-2013. Regression models were developed to estimate FEV1 rate of decline. Multivariable logistic analysis was used to assess if spirometric risk factors were associated with FEV1 decline. MEASUREMENTS AND MAIN RESULTS: 3,029 subjects were in the study cohort. Approximately 15% of the cohort had a substantial decline in lung function ≥5% predicted/year. In multivariable models adjusted for confounders, FEV1/FVC ratio <0.8 (Odds Ratio (OR) 1.63, 95% confidence interval (CI) 1.31 to 2.02) and history of FEV1% predicted variability (OR 2.35,95%CI 1.74 to 3.18) were associated with rapid lung function decline. CONCLUSIONS: Even among adults with early-stage lung disease, approximately 15% are shown to progress and experience a large decline in lung function. This reinforces the concept that lung function in early-stage CF is not normal or mild. Rather, lung function decline may be delayed, but not avoided, in these individuals. Variability in FEV1% predicted and airway obstruction as measured by FEV1/FVC ratio may identify individuals at increased risk of decline. Adults with early-stage lung disease should be followed in clinic to monitor for onset of decline.

Predicting Survival in Patients With Pulmonary Arterial Hypertension: The REVEAL Risk Score Calculator 2.0 and Comparison With ESC/ERS-Based Risk Assessment Strategies.

BACKGROUND: Pulmonary arterial hypertension is a progressive, fatal disease. Published treatment guidelines recommend treatment escalation on the basis of regular patient assessment with the goal of achieving or maintaining low-risk status. Various strategies are available to determine risk status. This analysis describes an update of the Registry to Evaluate Early and Long-Term PAH Disease Management (REVEAL) risk calculator (REVEAL 2.0) and compares it with recently published European Society of Cardiology/Respiratory Society guideline-derived risk assessment strategies. METHODS: A subpopulation from the US-based registry REVEAL that survived ≥ 1 year postenrollment (baseline for this cohort) was analyzed. For REVEAL 2.0, point values and cutpoints were reassessed, and new variables were evaluated. The Kaplan-Meier method was used to estimate survival at 12 months postbaseline; discrimination was quantified using the c-statistic. Mortality estimates and discrimination were compared between REVEAL 2.0 and Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) and French Pulmonary Hypertension Registry (FPHR) risk assessment strategies. For this comparison, a three-category REVEAL 2.0 score was computed in which patients were classified as low-, intermediate-, or high-risk. RESULTS: REVEAL 2.0 demonstrated similar discrimination as the original calculator in this subpopulation (c-statistic = 0.76 vs 0.74), provided excellent separation of risk among the risk categories, and predicted clinical worsening as well as mortality in patients who were followed ≥ 1 year. The REVEAL 2.0 three-category score had greater discrimination (c-statistic = 0.73) than COMPERA (c-statistic = 0.62) or FPHR (c-statistic = 0.64). Compared with REVEAL 2.0, COMPERA and FPHR both underestimated and overestimated risk. CONCLUSIONS: REVEAL 2.0 demonstrates greater risk discrimination than the COMPERA and FPHR risk assessment strategies in patients enrolled in REVEAL. After external validation, the REVEAL 2.0 calculator can assist clinicians and patients in making informed treatment decisions on the basis of individual risk profiles. TRIAL REGISTRY: ClinicalTrials.gov; No. NCT00370214; URL: www.clinicaltrials.gov.

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.

Association of High-Dose Ibuprofen Use, Lung Function Decline, and Long-Term Survival in Children with Cystic Fibrosis.

RATIONALE: Cystic fibrosis deaths result primarily from lung function loss, so chronic respiratory therapies, intended to preserve lung function, are cornerstones of cystic fibrosis care. Although treatment-associated reduction in rate of lung function loss should ultimately improve cystic fibrosis survival, no such relationship has been described for any chronic cystic fibrosis therapy. In part, this is because the ages of most rapid lung function decline-early adolescence-precede the median age of cystic fibrosis deaths by more than a decade. OBJECTIVES: To study associations of high-dose ibuprofen treatment with the rate of forced expiratory volume in 1 second decline and mortality among children followed in the Epidemiologic Study of Cystic Fibrosis and subsequently in the U.S. Cystic Fibrosis Foundation Patient Registry. METHODS: We performed a matched cohort study using data from Epidemiologic Study of Cystic Fibrosis. Exposure was defined as high-dose ibuprofen use reported at ≥80% of encounters over 2 years. Unexposed children were matched to exposed children 5:1 using propensity scores on the basis of demographic, clinical, and treatment covariates. The rate of decline of percent predicted forced expiratory volume in 1 second during the 2-year follow-up period was estimated by mixed-effects modeling with random slopes and intercepts. Survival over 16 follow-up years in the U.S. Cystic Fibrosis Foundation Patient Registry was compared between treatment groups by using proportional hazards modeling controlling for matching and covariates. RESULTS: We included 775 high-dose ibuprofen users and 3,665 nonusers who were well matched on demographic, clinical, and treatment variables. High-dose ibuprofen users declined on average 1.10 percent predicted forced expiratory volume in 1 second/yr (95% confidence interval; 0.51, 1.69) during the 2-year treatment period, whereas nonusers declined at a rate of 1.76% percent predicted forced expiratory volume in 1 second/yr (95% confidence interval; 1.48, 2.04) during the corresponding 2-year period, a 37.5% slower decline among users compared with nonusers (95% confidence interval; 0.4%, 71.3%; P = 0.046). The users had better subsequent survival (P < 0.001): the unadjusted and adjusted hazard ratios for mortality (high-dose ibuprofen/non-high-dose ibuprofen) (95% confidence interval) were 0.75 (0.64, 0.87) and 0.82 (0.69, 0.96). CONCLUSIONS: In a propensity-score matched cohort study of children with cystic fibrosis, we observed an association between high-dose ibuprofen use and both slower lung function decline and improved long-term survival. These results are consistent with the hypothesis that treatment-associated reduction of lung function decline in children with cystic fibrosis leads to improved survival.

Medical Expenditures and Earnings Losses Among US Adults With Arthritis in 2013.

OBJECTIVE: We estimated the economic impact of arthritis using 2013 US Medical Expenditure Panel Survey (MEPS) data. METHODS: We calculated arthritis-attributable and all-cause medical expenditures for adults age ≥18 years and arthritis-attributable earnings losses among those ages 18-64 years who had ever worked. We calculated arthritis-attributable costs using multistage regression-based methods, and conducted sensitivity analyses to estimate costs for 2 other arthritis definitions in MEPS. RESULTS: In 2013, estimated total national arthritis-attributable medical expenditures were $139.8 billion (range $135.9-$157.5 billion). Across expenditure categories, ambulatory care expenditures accounted for nearly half of arthritis-attributable expenditures. All-cause expenditures among adults with arthritis represented 50% of the $1.2 trillion national medical expenditures among all US adults in MEPS. Estimated total national arthritis-attributable earning losses were $163.7 billion (range $163.7-$170.0 billion). The percentage with arthritis who worked in the past year was 7.2 percentage points lower than those without arthritis (76.8% [95% confidence interval (95% CI)] 75.0-78.6 and 84.0% [95% CI 82.5-85.5], respectively, adjusted for sociodemographics and chronic conditions). Total arthritis-attributable medical expenditures and earnings losses were $303.5 billion (range $303.5-$326.9 billion). CONCLUSION: Total national arthritis-attributable medical care expenditures and earnings losses among adults with arthritis were $303.5 billion in 2013. High arthritis-attributable medical expenditures might be reduced by greater efforts to reduce pain and improve function. The high earnings losses were largely attributable to the substantially lower prevalence of working among those with arthritis compared to those without, signaling the need for interventions that keep people with arthritis in the workforce.

Treatment Setting and Outcomes of Cystic Fibrosis Pulmonary Exacerbations.

RATIONALE: There are important gaps in knowledge of the optimal treatment of cystic fibrosis pulmonary exacerbations. Previous observational studies comparing inpatient with outpatient treatment have suffered from methodologic weaknesses, especially indication bias. OBJECTIVES: We analyzed data from the Epidemiologic Study of Cystic Fibrosis using techniques to control for indication bias to determine whether there is an advantage to inpatient treatment of cystic fibrosis pulmonary exacerbations. METHODS: We identified typical pulmonary exacerbations in patients ages 6 years and older during the 3-year observation period ending in 2005. In our primary analysis, we used the instrumental variables method, implemented using two-stage least squares regression, to evaluate the effect of the proportion of total time that intravenous treatment was administered on an inpatient (versus outpatient) basis on the likelihood of return of percent predicted forced expiratory volume in 1 second to greater than or equal to 90% of baseline post-treatment. We also evaluated two other indicators of treatment setting, three other measures of treatment response, and two alternative modeling techniques, and we also looked for differences between children and adults. RESULTS: Our final analysis included 4,497 pulmonary exacerbations in 2,773 individual patients at 75 sites. We calculated the mean proportion of intravenous treatment time that was provided in the hospital setting at each site. The median across sites was 0.581 (interquartile range, 0.396-0.753). The median treatment success rate across sites was 74.2% (interquartile range, 67.9 to 79.2%). Univariate analysis and two-stage least squares models showed a positive relationship between treatment success and proportion of inpatient treatment days. Our primary model revealed an absolute increase of 9.08% (95% confidence interval, 2.55-15.61; P = 0.006) in the achievement of a return of percent predicted forced expiratory volume in 1 second to greater than or equal to 90% of baseline comparing complete inpatient treatment with no inpatient treatment. Treatment response was not related to duration of intravenous therapy. Similar results were found for all our modeling techniques and outcomes. CONCLUSIONS: Patients with cystic fibrosis treated at sites with more reliance on inpatient treatment were more likely to achieve successful forced expiratory volume in 1 second recovery. There was no relationship between treatment duration and recovery of forced expiratory volume in 1 second.

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.

Cystic fibrosis clinical characteristics associated with dornase alfa treatment regimen change.

BACKGROUND: When the chronic respiratory therapy dornase alfa was made commercially available for cystic fibrosis (CF) more than 20 years ago, two regimens were approved: 2.5 mg inhaled once daily (QD) or twice daily (BID). In the intervening years, there has been little guidance as to when to use each regimen. We have studied clinical practice patterns captured in the Epidemiologic Study of CF (ESCF) during the decade following dornase alfa approval (1994-2005) to better understand clinical characteristics associated with QD versus BID dornase alfa use. Methods We studied the characteristics of ESCF patients who received either dornase alfa regimen for at least 12 months and who were then switched to the alternate regimen for at least 6 months and who had adequate data available around the time of the switch. Average lung function and weight-for-age (WFA) z-scores, numbers of intravenous (IV) antibiotic-treated pulmonary exacerbations, and prevalence of signs and symptoms were determined for 6-month periods capturing the beginning (FIRST) and the end (LAST) of the initial regimen, the 6 months preceding the final 6 months of the initial regimen (PRIOR), and the beginning of the second regimen (POST). Changes in values from FIRST to LAST, PRIOR to LAST, and LAST to POST were studied to better understand clinical scenarios associated with decisions to change regimens. RESULTS: A total of 1342 QD and 574 BID regimens were studied with median durations of 3.19 and 2.09 years, respectively. On average, patients beginning BID regimens had worse lung function and a greater number of pulmonary exacerbations treated with IV antibiotics than those beginning QD regimens. However, by the time of regimen switch, patients switching from QD to BID dornase alfa had experienced substantial deterioration with respect to pulmonary exacerbations and signs and symptoms, whereas patients switching from BID to QD had not. Interestingly, incidence of IV-treated pulmonary exacerbations and signs and symptom prevalence decreased for both populations after regimen switch. CONCLUSIONS: We have studied populations of patients with CF receiving dornase alfa who were switched between regimens to characterize clinical course. Our results suggest that the most common clinical attribute associated with switching from QD to BID dornase alfa was a marked deterioration in stability characterized by increased incidence and frequency of pulmonary exacerbation. For this population, deterioration in lung function did not appear to be a driver for this switch. In contrast, patients receiving BID dornase alfa who were ultimately switched to QD appeared to be clinically stable, on average, suggesting that treatment burden and cost may have been drivers of the decision to switch regimens.

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.

Risk factors for mortality before age 18 years in cystic fibrosis.

BACKGROUND: Understanding early-life risk factors for childhood death in cystic fibrosis (CF) is important for clinical care, including the identification of effective interventions. METHODS: Data from the Epidemiologic Study of Cystic Fibrosis (ESCF) collected 1994-2005 were linked with the Cystic Fibrosis Foundation Patient Registry (CFFPR) demographic and mortality data from 2013. Inclusion criteria were ≥1 visit annually at age 3-5 years and ≥1 FEV1 measurement at age 6-8 years. Demographic data, nutritional parameters, pulmonary signs and symptoms, microbiology, and FEV1 were evaluated as risk factors for death before age 18 years. Multivariable Cox proportional hazards regression was used to model the simultaneous effects of risk factors associated with death before age 18 years. RESULTS: Among 5365 patients enrolled in ESCF who met inclusion criteria, 3880 (72%) were linked to the CFFPR. Among these, 191 (5.7%) died before age 18 years; median age at death was 13.4 ± 3.1 years. Multivariable regression showed clubbing, crackles, female sex, unknown CFTR genotype, minority race or ethnicity, Medicaid insurance (a proxy of low socioeconomic status), Pseudomonas aeruginosa on 2 or more cultures, and weight-for-age <50th percentile were significant risk factors for death regardless of inclusion of FEV1 at age 6-8 years in the model. CONCLUSION: We identified multiple risk factors for childhood death of patients with CF, all of which remained important after incorporating FEV1 at age 6-8 years. Among the factors identified were the presence of clubbing or crackles at age 3-5 years, signs which are not routinely collected in registries.

Effectiveness of triple therapy with direct-acting antivirals for hepatitis C genotype 1 infection: application of propensity score matching in a national HCV treatment registry.

BACKGROUND: Observational studies are used to measure the effectiveness of an intervention in non-experimental, real world scenarios at the population level and are recognised as an important component of the evidence pyramid. Such data can be accrued through prospective cohort studies and a patient registry is a proven method for this type of study. The national hepatitis C (HCV) registry was established in Ireland in 2012 with the aim of monitoring the clinical and economic outcomes from new, high cost regimens for the treatment of HCV infection. A sustained virological response (SVR) 24 weeks following completion of therapy with interferon-containing regimens is considered a cure. Non-randomisation in these studies can result in confounding or selection bias. Propensity score (PS) matching is one of a number of statistical tools that can be used to mitigate the effects of confounding in observational studies. METHODS: We analysed the data of 309 patients who underwent triple therapy treatment with telaprevir (TPV) in combination with pegylated-interferon and ribavirin (PR) or boceprevir (BOC)/PR between June 2012 and December 2014. The decision to initiate treatment and the selection of the treatment regimen was at the discretion of the physician. To adjust for confounding, three approaches to propensity score matching were assessed Adjusted sustained-virological response rates (SVR), odds ratios, p-values and 95% confidence intervals were calculated from the three PS matched dataset. RESULTS: Prior to matching, the unadjusted sustained virological response rates 24 weeks after treatment complete (SVR24) were 74% (n = 158/215) and 61% (n = 57/94) for telaprevir/PR and boceprevir/PR, respectively. After matching, adjusted SVR24 rates were between 73-74% and 60-61% for telaprevir/PR and boceprevir/PR, respectively. CONCLUSION: Efficacy rates were comparable with those reported in pivotal clinical trials and real world studies. After adjusting for confounding, we conclude that there was no difference in treatment effect after PS matching. The small sample size limits the conclusions that can be made about the effect of PS matching. Propensity score adjustment remains a tool that can be applied to future analysis, however, we suggest, where possible, using a larger sample size in order to reduce the uncertainty around the outcomes.