The Elusive Role of Airway Infection in Cystic Fibrosis Exacerbation

Update on the diagnosis and management of cystic fibrosis pulmonary exacerbations

Pulmonary exacerbations in people with cystic fibrosis are associated with significant morbidity and reduced quality of life. Pulmonary exacerbation treatment guidelines, published by an expert panel assembled by the Cystic Fibrosis Foundation nearly 15 years ago, were primarily consensus-based as there were several gaps in the evidence base. In particular, limited evidence existed regarding optimal pulmonary exacerbation treatment strategies, including duration of antibiotic therapy, treatment location, antibiotic selection, and the role of systemic corticosteroids. Over the last decade, results from observational studies and large multi-center randomized controlled trials have begun to answer important questions related to pulmonary exacerbation treatment. This review focuses on the diagnosis, etiology, and changing epidemiology of pulmonary exacerbations, and also summarizes the most recent and up-to-date studies describing pulmonary exacerbation treatment. Finally, this review provides consideration for future pulmonary exacerbation research priorities, particularly in the current highly effective modulator therapy era.

Prevalence and Clinical Impact of Respiratory Viral Infections from the STOP2 Study of Cystic Fibrosis Pulmonary Exacerbations

Rationale: Rates of viral respiratory infection (VRI) are similar in people with cystic fibrosis (CF) and the general population; however, the associations between VRI and CF pulmonary exacerbations (PEx) require further elucidation.Objectives: To determine VRI prevalence during CF PEx and evaluate associations between VRI, clinical presentation, and treatment response.Methods: The STOP2 (Standardized Treatment of Pulmonary Exacerbations II) study was a multicenter randomized trial to evaluate different durations of intravenous antibiotic therapy for PEx. In this ancillary study, participant sputum samples from up to three study visits were tested for respiratory viruses using multiplex polymerase chain reactions. Baselines and treatment-associated changes in mean lung function (percent predicted forced expiratory volume in 1 s), respiratory symptoms (Chronic Respiratory Infection Symptom Score), weight, and C-reactive protein were compared as a function of virus detection. Odds of PEx retreatment within 30 days and future PEx hazard were modeled by logistic and Cox proportional hazards regression, respectively.Results: A total of 1,254 sputum samples from 621 study participants were analyzed. One or more respiratory viruses were detected in sputum samples from 245 participants (39.5%). Virus-positive participants were more likely to be receiving CF transmembrane conductance regulator modulator therapy (45% vs. 34%) and/or chronic azithromycin therapy (54% vs. 44%) and more likely to have received treatment for nontuberculous Mycobacterium infection in the preceding 2 years (7% vs. 3%). At study visit 1, virus-positive participants were more symptomatic (mean Chronic Respiratory Infection Symptom Score, 53.8 vs. 51.1), had evidence of greater systemic inflammation (log10 C-reactive protein concentration, 1.32 log10 mg/L vs. 1.23 log10 mg/L), and had a greater drop in percent predicted forced expiratory volume in 1 second from the prior 6-month baseline (5.8 vs. 3.6). Virus positivity was associated with reduced risk of future PEx (hazard ratio, 0.82; 95% confidence interval, 0.69-0.99; P = 0.034) and longer median time to next PEx (255 d vs. 172 d; P = 0.021) compared with virus negativity.Conclusions: More than one-third of STOP2 participants treated for a PEx had a positive test result for a respiratory virus with more symptomatic initial presentation compared with virus-negative participants, but favorable long-term outcomes. More refined phenotyping of PEx, taking VRIs into account, may aid in optimizing personalized management of PEx.Clinical trial registered with www.clinicaltrials.gov (NCT02781610).

Home-spirometry exacerbation profiles in children with cystic fibrosis

BACKGROUND

Pulmonary exacerbations (PEx) are strong predictors of respiratory disease progression in children with cystic fibrosis (CwCF) and may be associated with persistent decreased lung function after acute management. Telemonitoring devices can be used for early detection and monitoring of PEx, but its utility is debated.

RESEARCH QUESTION

Which symptoms and telemonitoring spirometry characterics are related to outcome dynamics following initial PEx management?

METHODS

This retrospective study included CwCF followed at Bordeaux University Hospital, France. All severe PEx episodes treated with intravenous (IV) antibiotics (ATB) between 1 January 2017 and 31 December 2021 in CwCF using home telemonitoring were analyzed. Symptoms and home spirometry data were collected 45 days before and up to 60 days after each IV ATB course. We defined three response profiles based on terciles of baseline forced expiratory volume in 1 s (FEV1 ) recovery.

RESULTS

A total of 346 IV ATB courses for PEx were administered to 65 CwCF during the study period. The drop in FEV1 became significant 8 days before IV ATB initiation. Forty-one percent of IV ATB courses failed to restore baseline FEV1 . The magnitude of FEV1 drop and a greater delay in the initiation of treatment correlated with a low response level. On the 14th day of the IV treatment, a FEV1 recovery less than 94% of baseline was associated with a nonresponder profile.

INTERPRETATION

Home spirometry may facilitate the early recognition of PEx to implement earlier interventions. This study also provides an outcome lung function threshold which identifies low responders to IV ATB.