Cystic Fibrosis News Digest — Issue 01

Grace G Kim, Taryn Wong, Jonathan Rayment, et al.

Summary: This Canadian observational study analyzed work productivity and activity impairment (WPAI) outcomes in 146 people with cystic fibrosis (pwCF) before and after one year of elexacaftor/tezacaftor/ivacaftor (ETI), drawing on data from two studies: CAN-IMPACT-CF and REAL-ETI-CF. Among the 75 participants who were employed, absenteeism fell from 13.1% to 3.3%, presenteeism from 24.9% to 8.8%, and overall work productivity loss from 30% to 10.8%. Across the full cohort, overall activity impairment dropped from 30.1% to 15.1%. Improvements in productivity and activity correlated most strongly with gains in CFQ-R Role Functioning, Physical Functioning, and Respiratory domains.

Why it matters: Work productivity and daily activity are patient-centered outcomes with direct socioeconomic implications that are often underrepresented in clinical trials, which tend to prioritize lung function metrics such as ppFEV₁. Demonstrating that ETI yields meaningful functional gains in real-world settings — beyond the controlled environment of registration trials — strengthens the health-economic case for access and reimbursement. For patients, reduced absenteeism and activity impairment represent tangible improvements in life participation, financial stability, and social integration. These findings also support the argument that the full value of CFTR modulators extends well beyond traditional pulmonary endpoints.

Expert perspective: This is a useful piece of real-world evidence, though several methodological considerations should temper enthusiasm about its conclusions.

The most immediate limitation is sample size. Only 75 of 146 participants were employed and therefore contributed to the primary WPAI work productivity outcomes. Employment status itself is not random — healthier patients are more likely to be employed at baseline — which introduces meaningful selection bias into the productivity estimates. The before-after paired design cannot distinguish the effect of ETI from concurrent trends such as natural disease progression, regression to the mean, seasonal variation in symptoms, or other interventions introduced during the same period. There is no control group.

The WPAI instrument is self-reported and subject to well-known limitations including recall bias and social desirability, though self-reported productivity is arguably the most meaningful measure from the patient perspective. The correlations between WPAI improvements and CFQ-R domain improvements (ρ = −0.53 to −0.66) are moderate to moderately strong and internally consistent, but the correlational analysis is not adjusted for baseline characteristics and cannot establish directionality or causation. One year of follow-up leaves open important questions about durability. Combining two separate observational studies also raises questions about protocol harmonization and data collection consistency.

Despite these limitations, the magnitude of the productivity improvements — roughly halving absenteeism and overall work productivity loss — is clinically plausible. The study adds patient-centered, socioeconomically relevant evidence to a literature dominated by ppFEV₁ and BMI endpoints, and contributes meaningfully to health technology assessment frameworks that consider broader value-of-treatment metrics. It is useful incremental evidence that fills a real gap in the real-world ETI literature and is particularly relevant to Canadian health policy and payer contexts.

Relevance: Cystic Fibrosis

Source: https://pubmed.ncbi.nlm.nih.gov/42736062/

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Ashley Han, Matt Hall, Elizabeth Cromwell, et al. ________________________________________________________________________________________________ Editor’s note: First of all, congratulations to Liz, the registry team, and all the authors on this publication! Having worked with some of you for many years, I’m especially happy to see this work published. ________________________________________________________________________________________________ Summary: This retrospective cohort study linked the CF Foundation Patient Registry with the Pediatric Health Information System (PHIS) to examine associations between the Childhood Opportunity Index (COI) — a composite area-level socioeconomic measure — and healthcare utilization among 8,177 children with CF across 2009–2022. Children living in the lowest COI quintiles had significantly higher risks of hospitalization compared to those in the highest quintile, with the steepest gradient observed for respiratory-related hospitalizations (RR 1.60 for the very low COI group). Emergency room visits and ambulatory surgeries were also examined. The findings reinforce that where a child lives meaningfully shapes their disease burden and care patterns.

Why it matters: Health disparities in CF have been increasingly recognized, yet granular data on how neighborhood-level factors specifically drive acute care utilization has been limited. This study addresses that gap using a well-powered, registry-linked dataset spanning over a decade, lending credibility to the observed associations. The findings are operationally significant: if socioeconomic context predicts hospitalization risk independently of disease severity or CFTR genotype, then clinical programs and payers may need to incorporate social risk stratification into care planning and resource allocation. For the CF community navigating the CFTR modulator era, understanding why some children still experience high acute-care burdens despite available therapies is a pressing and practical question.

Expert perspective: The CFF Registry–PHIS linkage is a methodologically sound approach, combining clinical granularity from the registry with validated encounter-level hospital data from PHIS. The sample size is substantial — over 65,000 hospital encounters — and generalized estimating equations with clustering on hospital are appropriate for the data structure. The dose-response pattern across COI quintiles adds plausibility.

That said, several limitations deserve attention. COI is an area-level, ecological exposure assigned by residential zip code or census tract; it does not capture individual household socioeconomic status, and ecological inference remains a persistent concern. The study is retrospective and observational, so unmeasured confounding is a genuine threat. CFTR genotype distribution, modulator eligibility and uptake, baseline lung function, pancreatic status, and microbiology all differ by socioeconomic stratum and could independently drive hospitalization risk. The abstract does not detail which covariates were adjusted in the multivariable models, making it difficult to assess how much of the COI signal is independent of disease severity.

The study spans 2009–2022, encompassing the dramatic expansion of highly effective CFTR modulator therapy beginning around 2019–2020. Whether COI-related disparities in hospitalization have narrowed, persisted, or widened in the modulator era is a critically important question that a pooled analysis across this entire period may obscure. Additionally, PHIS captures encounters at participating children's hospitals only — children receiving care at smaller community hospitals or adult centers, disproportionately those in rural or lower-resource settings, are not represented, which could underestimate the true disparity.

The conclusions are appropriately measured, calling for future research into underlying drivers rather than claiming causal mechanisms. The field would benefit from studies that move beyond describing the disparity gradient toward testing specific mediators — insurance type, distance to CF care center, modulator access, or nutritional support. Registry linkage with individual-level rather than area-level social determinants of health data would strengthen future work considerably.

Relevance: CF Registry and Real-World Evidence

Source: https://pubmed.ncbi.nlm.nih.gov/42697797/

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Marianne S Muhlebach, Jane She, John J LiPuma, et al.

Summary: Using US CF Foundation Patient Registry data from 2011–2019, this study examined whether the benefits and risks of chronic inhaled antibiotic therapy have shifted alongside the introduction of CFTR modulators. Using inverse probability treatment weighting and generalized estimating equations across roughly 12,000–16,000 people with CF (pwCF) annually, the authors found that inhaled antibiotics were associated with increased risks of Aspergillus, Stenotrophomonas maltophilia, and Achromobacter infections. The lung-function benefit of inhaled antibiotics was present only in pwCF with chronic Pseudomonas aeruginosa (Pa) infection, was absent or negative in Pa-negative pwCF, and diminished progressively across successive CFTR-modulator eras.

Why it matters: Chronic inhaled antibiotics have been a cornerstone of CF pulmonary management for decades, but the therapeutic landscape has changed dramatically with the advent of highly effective modulator therapy (HEMT). This study provides registry-scale evidence that the benefit-risk calculus for inhaled antibiotics may need recalibration — particularly for Pa-negative patients, who appear to bear infection risk without lung-function benefit, and for patients on modulators, whose Pa burden and baseline lung function have improved substantially. These findings carry direct implications for prescribing practice, guideline development, and the design of future comparative-effectiveness studies.

Expert perspective: This is a methodologically serious registry study tackling a clinically important and underexplored question. The sample is large, nationally representative within the US CF population, covers nine years spanning three modulator eras, and employs inverse probability treatment weighting to address treatment-selection bias. Leeds criteria for Pa infection status add rigor to the exposure stratification.

That said, several limitations deserve explicit acknowledgment. The study period ends in 2019, predating the widespread uptake of elexacaftor/tezacaftor/ivacaftor (ETI) — the modulator combination that has most dramatically altered Pa prevalence, lung function trajectories, and exacerbation rates. The three modulator eras studied represent a period of partial and heterogeneous modulator access, and the trajectory of diminishing antibiotic benefit may steepen considerably in the ETI era. Extrapolating these findings to current practice therefore requires caution.

The observational design, even with weighting, cannot fully eliminate confounding by indication. Physicians prescribing inhaled antibiotics to Pa-negative patients may be responding to clinical signals incompletely captured in registry fields. The association between inhaled antibiotics and Aspergillus or gram-negative co-infections is biologically plausible — antibiotics alter airway microbiome composition and may select for fungi and intrinsically resistant organisms — but causality cannot be established from these data. Reverse causation is also possible. The finding that Pa-negative pwCF prescribed inhaled antibiotics had worse lung function trajectories is clinically concerning but particularly susceptible to residual confounding, as this group likely contains patients prescribed antibiotics for reasons not well captured in registry data.

The clinical bottom line is pragmatically important: for pwCF who have eradicated or never acquired chronic Pa — a growing proportion in the modulator era — continued prescription of inhaled antibiotics deserves active reassessment rather than reflexive continuation. For those with chronic Pa, the benefit appears to persist but to be attenuating. This study will not by itself change guidelines, but it builds a credible evidential case for prospective trials or updated registry analyses incorporating ETI-era data to guide deprescribing decisions.

Relevance: Cystic Fibrosis | CF Registry and Real-World Evidence

Source: https://pubmed.ncbi.nlm.nih.gov/42767597/

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Lieke Roeke, Liesbeth I van de Ven, Steffie E M Vonk, et al.

Summary: This cross-sectional Dutch single-center study assessed medication adherence in 43 people with cystic fibrosis (pwCF) — children and adults — using three complementary methods: pharmacy refill data (medication possession ratio, MPR), self-reported adherence (MARS-5 questionnaire), and structured medication reviews conducted by pharmacists. Adherence to CFTR modulators was consistently high across all three methods (72–92%), while adherence to supportive therapies (vitamins, pancreatic enzymes, inhalers, nebulizers) was substantially lower and more variable (56–78%). Structured medication reviews identified four non-adherent patients missed by the other two methods and uncovered 51 drug-related problems (DRPs) across 41 of 43 participants, all of which led to accepted clinical interventions.

Why it matters: The finding that adherence to CFTR modulators is considerably higher than adherence to supportive therapies is clinically important. Patients appear to prioritize — consciously or not — the therapy most visibly transformative in their disease experience. The practical implication is that supportive therapies, despite being fundamental to nutritional status, pulmonary function, and long-term outcomes, may be quietly underused even in motivated, clinic-engaged populations. The demonstration that structured medication reviews added actionable clinical information beyond what refill data and self-report captured is a meaningful operational finding for CF care teams considering how to deploy pharmacist resources.

Expert perspective: The study is methodologically straightforward and appropriately modest in its claims. The sample size of 43 patients from a single Dutch tertiary center is small — this is a feasibility and hypothesis-generating study — and restricts generalizability considerably. Patients attending a specialized academic CF center are not representative of the broader CF population and almost certainly represent a more adherent, more engaged subset. Adherence estimates from this group will likely overestimate adherence in community or less-resourced settings.

The three-method comparison is the study's most interesting contribution. Each method captures something different: MPR reflects dispensing behavior, MARS-5 reflects self-perception of adherence, and medication reviews reveal clinical complexity — polypharmacy, practical barriers, unintentional non-adherence, or inappropriate prescribing. The notably lower CFTR modulator adherence detected by medication review compared to MPR (72% vs. 92%) confirms that pharmacy refill data, while convenient and scalable, may overestimate true medication-taking behavior. Patients can possess a medication without taking it reliably.

The finding that all 51 proposed DRP interventions were accepted by treating physicians warrants a moment of reflection: this could reflect the genuine quality of pharmacist recommendations, or it could reflect social dynamics within a small team operating within the same institutional culture. Independent validation would strengthen this claim. The cross-sectional design cannot address whether medication reviews actually improve adherence over time or produce measurable clinical benefit — that requires a longitudinal or interventional design with a comparison group.

From a real-world data perspective, this study demonstrates something important for CF registries that rely on administrative pharmacy data: refill-based and patient-reported measures give incomplete and sometimes discordant pictures of adherence. Structured medication reviews are resource-intensive and unlikely to be feasible at registry scale, but their findings here could inform the development of better adherence proxies or trigger criteria for targeted pharmacist review.

Relevance: Cystic Fibrosis

Source: https://pubmed.ncbi.nlm.nih.gov/42667119/

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