Accurate reporting of adherence to inhaled therapies in adults with cystic fibrosis: methods to calculate "normative adherence"

Psychological interventions for improving adherence to inhaled therapies in people with cystic fibrosis

BACKGROUND

Adherence to treatment, including inhaled therapies, is low in people with cystic fibrosis (CF). Although psychological interventions for improving adherence to inhaled therapies in people with CF have been developed, no previous published systematic review has evaluated the evidence for efficacy of these interventions.

OBJECTIVES

The primary objective of the review was to assess the efficacy of psychological interventions for improving adherence to inhaled therapies in people with cystic fibrosis (CF). The secondary objective was to establish the most effective components, or behaviour change techniques (BCTs), used in these interventions.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, which is compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched databases (PubMed; PsycINFO; EBSCO; Scopus; OpenGrey), trials registries (World Health Organization International Clinical Trials Registry Platform; US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov), and the reference lists of relevant articles and reviews, with no restrictions on language, year or publication status. Date of search: 7 August 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different types of psychological interventions for improving adherence to inhaled therapies in people with CF of any age, or comparing psychological interventions with usual care. We included quasi-RCTs if we could reasonably assume that the baseline characteristics were similar in both groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and completed data extraction, risk of bias assessments, and BCT coding (using the BCT Taxonomy v1) for all included trials. We resolved any discrepancies by discussion, or by consultation with a third review author as necessary. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included 10 trials (1642 participants) in the review (children and adolescents in four trials; adults in five trials; and children and adults in one trial). Nine trials compared a psychological intervention with usual care; we could combine data from some of these in a number of quantitative analyses. One trial compared a psychological intervention with an active comparator (education plus problem-solving (EPS)). We identified five ongoing trials. Psychological interventions were generally multi-component and complex, containing an average of 9.6 BCTs (range 1 to 28). The two most commonly used BCTs included 'problem-solving' and 'instruction on how to perform the behaviour'. Interventions varied in their type, content and mode of delivery. They included a problem-solving intervention; a paper-based self-management workbook; a telehealth intervention; a group training programme; a digital intervention comprising medication reminders and lung function self-monitoring; a life-coaching intervention; a motivational interviewing (MI) intervention; a brief MI intervention (behaviour change counselling); and a digital intervention combined with behaviour change sessions. Intervention duration ranged from 10 weeks to 12 months. Assessment time points ranged from six to eight weeks up to 23 months. Psychological interventions compared with usual care We report data here for the 'over six months and up to 12 months' time point. We found that psychological interventions probably improve adherence to inhaled therapies (primary outcome) in people with CF compared with usual care (mean difference (MD) 9.5, 95% confidence interval (CI) 8.60 to 10.40; 1 study, 588 participants; moderate-certainty evidence). There was no evidence of a difference between groups in our second primary outcome, treatment-related adverse events: anxiety (MD 0.30, 95% CI -0.40 to 1.00; 1 study, 535 participants), or depression (MD -0.10, 95% CI -0.80 to 0.60; 1 study, 534 participants), although this was low-certainty evidence. For our secondary outcomes, there was no evidence of a difference between groups in terms of lung function (forced expiratory volume in one second (FEV1) % predicted MD 1.40, 95% CI -0.20 to 3.00; 1 study, 556 participants; moderate-certainty evidence); number of pulmonary exacerbations (adjusted rate ratio 0.96, 95% CI 0.83 to 1.11; 1 study, 607 participants; moderate-certainty evidence); or respiratory symptoms (MD 0.70, 95% CI -2.40 to 3.80; 1 study, 534 participants; low-certainty evidence). However, psychological interventions may improve treatment burden (MD 3.90, 95% CI 1.20 to 6.60; 1 study, 539 participants; low-certainty evidence). The overall certainty of the evidence ranged from low to moderate across these outcomes. Reasons for downgrading included indirectness (current evidence included adults only whereas our review question was broader and focused on people of any age) and lack of blinding of outcome assessors. Psychological interventions compared with an active comparator For this comparison the overall certainty of evidence was very low, based on one trial (n = 128) comparing an MI intervention to EPS for 12 months. We are uncertain whether an MI intervention, compared with EPS, improves adherence to inhaled therapies, lung function, or quality of life in people with CF, or whether there is an effect on pulmonary exacerbations. The included trial for this comparison did not report on treatment-related adverse events (anxiety and depression). We downgraded all reported outcomes due to small participant numbers, indirectness (trials included only adults), and unclear risk of bias (e.g. selection and attrition bias).

AUTHORS' CONCLUSIONS

Due to the limited quantity of trials included in this review, as well as the clinical and methodological heterogeneity, it was not possible to identify an overall intervention effect using meta-analysis. Some moderate-certainty evidence suggests that psychological interventions (compared with usual care) probably improve adherence to inhaled therapies in people with CF, without increasing treatment-related adverse events, anxiety and depression (low-certainty evidence). In future review updates (with ongoing trial results included), we hope to be able to establish the most effective BCTs (or 'active ingredients') of interventions for improving adherence to inhaled therapies in people with CF. Wherever possible, investigators should make use of the most objective measures of adherence available (e.g. data-logging nebulisers) to accurately determine intervention effects. Outcome reporting needs to be improved to enable combining or separation of measures as appropriate. Likewise, trial reporting needs to include details of intervention content (e.g. BCTs used); duration; intensity; and fidelity. Large trials with a longer follow-up period (e.g. 12 months) are needed in children with CF. Additionally, more research is needed to determine how to support adherence in 'under-served' CF populations.

Use of inhaled antibiotics among Danish patients with cystic fibrosis

BACKGROUND

Inhaled antibiotics are an important part of cystic fibrosis (CF) airway disease management and should be individualized to fit the microorganism and match patient needs. To investigate the implementation of personalized treatment, this study mapped the use of different types of inhaled antibiotics and adherence patterns.

METHODS

We performed individual structured interviews in a cross-sectional study at the CF Centre in Copenhagen, Denmark. Patients with CF older than 15 years attending clinical consultations were included. Clinical data were obtained from centralized databases.

RESULTS

Among 149 participants, 107 (72%) had indication for treatment with inhaled antibiotics. In this group, 97 (91%) reported the use of inhaled antibiotics within the last 12 months. Change from one inhaled antibiotic to another during that period was reported by 31 (29%), and 17 (25%) with Pseudomonas aeruginosa had used off-label antibiotics. Adherence to a minimum of one daily dose of antibiotic was reported by 78%, while adherence to all daily doses was 28 percentage points lower. Skipping inhalations was due to side effects and doubt about the effect in less than 5% of cases.

CONCLUSION

Change of inhaled antibiotics and use of off-label antibiotics for inhalation were common and side effects were a rare cause of nonadherence. This suggests satisfactory implementation of the principle of tailored antibiotic inhalation prescription in the Copenhagen CF population. Adherence to at least one daily inhalation dose was markedly higher than adherence to multiple daily inhalations.

Adherence to inhaled therapies over 4 years in people with cystic fibrosis

BACKGROUND

This study examined the drug-specific and overall adherence of teenagers and adults with cystic fibrosis (CF) to inhaled therapies, to assess the degree of adherence, stability over a period of 4 years, and its association with health outcomes.

METHODS

Fifty-five participants (30 women and 25 men) aged 14 years or older from two CF centers were enrolled in a retrospective review of inhaled medication adherence over 4 years. Adherence was assessed by the number of doses that were obtained by each participant based on the "e-prescription.gr" platform and the calculation of the medication possession ratio (MPR).

RESULTS

The mean composite MPR (cMPR) for the entire research period was 0.75 ± 0.19. A total of 43.4% of participants showed a variance of adherence <25%. Participants with stable adherence had a significantly higher mean cMPR compared with those with variable adherence (0.86 ± 0.16 vs. 0.66 ± 0.17, p < 0.001). A statistically significant difference between groups of patients with different degrees of mean cMPR and mean weight was observed (p = 0.011). Patients with a mean cMPR ≥0.80 weighed significantly more than those with moderate and low adherence. In addition, mean weight correlated significantly with the mean cMPR (Β [95% confidence interval] = 14.845 [0.191-29.498], r = 0.269, p = 0.047).

CONCLUSIONS

In our setting, the cMPR was easy to assess and showed that adherence was probably better than expected. The association of cMPR with weight should be further investigated. Stable adherence seemed to be related to high adherence. This observation could enhance our understanding of people with CF and their approach to treatment.

Implementing the use of objective medication adherence data in routine clinical practice via the digital CFHealthHub platform: situation analysis and strategy development using the theoretical domains framework

Background

Preventative inhaled treatments preserve lung function and reduce exacerbations in cystic fibrosis (CF). Self-reported adherence to these treatments is over-estimated. An online platform (CFHealthHub) has been developed with patients and clinicians to display real-time objective adherence data from dose-counting nebulisers, so that clinical teams can offer informed treatment support.

Methods

In this paper, we identify pre-implementation barriers to healthcare practitioners performing two key behaviours: accessing objective adherence data through the website CFHealthHub and discussing medication adherence with patients. We aimed to understand barriers during the pre-implementation phase, so that appropriate strategy could be developed for the scale up of implementing objective adherence data in 19 CF centres.

Thirteen semi-structured interviews were conducted with healthcare practitioners working in three UK CF centres. Qualitative data were coded using the theoretical domains framework (TDF), which describes 14 validated domains to implementation behaviour change.

Results

Analysis indicated that an implementation strategy should address all 14 domains of the TDF to successfully support implementation. Participants did not report routines or habits for using objective adherence data in clinical care. Examples of salient barriers included skills, beliefs in consequences, and social influence and professional roles. The results also affirmed a requirement to address organisational barriers. Relevant behaviour change techniques were selected to develop implementation strategy modules using the behaviour change wheel approach to intervention development.

Conclusions

This paper demonstrates the value of applying the TDF at pre-implementation, to understand context and to support the development of a situationally relevant implementation strategy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43058-022-00263-9.

An intervention to support adherence to inhaled medication in adults with cystic fibrosis: the ACtiF research programme including RCT

Background

People with cystic fibrosis frequently have low levels of adherence to inhaled medications.

Objectives

The objectives were to develop and evaluate an intervention for adults with cystic fibrosis to improve adherence to their inhaled medication.

Design

We used agile software methods to develop an online platform. We used mixed methods to develop a behaviour change intervention for delivery by an interventionist. These were integrated to become the CFHealthHub intervention. We undertook a feasibility study consisting of a pilot randomised controlled trial and process evaluation in two cystic fibrosis centres. We evaluated the intervention using an open-label, parallel-group randomised controlled trial with usual care as the control. Participants were randomised in a 1 : 1 ratio to intervention or usual care. Usual care consisted of clinic visits every 3 months. We undertook a process evaluation alongside the randomised controlled trial, including a fidelity study, a qualitative interview study and a mediation analysis. We undertook a health economic analysis using both a within-trial and model-based analysis.

Setting

The randomised controlled trial took place in 19 UK cystic fibrosis centres.

Participants

Participants were people aged ≥ 16 years with cystic fibrosis, on the cystic fibrosis registry, not post lung transplant or on the active transplant list, who were able to consent and not using dry-powder inhalers.

Intervention

People with cystic fibrosis used a nebuliser with electronic monitoring capabilities. This transferred data automatically to a digital platform. People with cystic fibrosis and clinicians could monitor adherence using these data, including through a mobile application (app). CFHealthHub displayed graphs of adherence data as well as educational and problem-solving information. A trained interventionist helped people with cystic fibrosis to address their adherence.

Main outcome measures

Randomised controlled trial – adjusted incidence rate ratio of pulmonary exacerbations meeting the modified Fuchs criteria over a 12-month follow-up period (primary outcome); change in percentage adherence; and per cent predicted forced expiratory volume in 1 second (key secondary outcomes). Process evaluation – percentage fidelity to intervention delivery, and participant and interventionist perceptions of the intervention. Economic modelling – incremental cost per quality-adjusted life-year gained.

Results

Randomised controlled trial – 608 participants were randomised to the intervention (n = 305) or usual care (n = 303). To our knowledge, this was the largest randomised controlled trial in cystic fibrosis undertaken in the UK. The adjusted rate of exacerbations per year (primary outcome) was 1.63 in the intervention and 1.77 in the usual-care arm (incidence rate ratio 0.96, 95% confidence interval 0.83 to 1.12; p = 0.638) after adjustment for covariates. The adjusted difference in mean weekly normative adherence was 9.5% (95% confidence interval 8.6% to 10.4%) across 1 year, favouring the intervention. Adjusted mean difference in forced expiratory volume in 1 second (per cent) predicted at 12 months was 1.4% (95% confidence interval –0.2% to 3.0%). No adverse events were related to the intervention. Process evaluation – fidelity of intervention delivery was high, the intervention was acceptable to people with cystic fibrosis, participants engaged with the intervention [287/305 (94%) attended the first intervention visit], expected mechanisms of action were identified and contextual factors varied between randomised controlled trial sites. Qualitative interviews with 22 people with cystic fibrosis and 26 interventionists identified that people with cystic fibrosis welcomed the objective adherence data as proof of actions to self and others, and valued the relationship that they built with the interventionists. Economic modelling – the within-trial analysis suggests that the intervention generated 0.01 additional quality-adjusted life-years at an additional cost of £865.91 per patient, leading to an incremental cost-effectiveness ratio of £71,136 per quality-adjusted life-year gained. This should be interpreted with caution owing to the short time horizon. The health economic model suggests that the intervention is expected to generate 0.17 additional quality-adjusted life-years and cost savings of £1790 over a lifetime (70-year) horizon; hence, the intervention is expected to dominate usual care. Assuming a willingness-to-pay threshold of £20,000 per quality-adjusted life-year gained, the probability that the intervention generates more net benefit than usual care is 0.89. The model results are dependent on assumptions regarding the duration over which costs and effects of the intervention apply, the impact of the intervention on forced expiratory volume in 1 second (per cent) predicted and the relationship between increased adherence and drug-prescribing levels.

Limitations

Number of exacerbations is a sensitive and valid measure of clinical change used in many trials. However, data collection of this outcome in this context was challenging and could have been subject to bias. It was not possible to measure baseline adherence accurately. It was not possible to quantify the impact of the intervention on the number of packs of medicines prescribed.

Conclusions

We developed a feasible and acceptable intervention that was delivered to fidelity in the randomised controlled trial. We observed no statistically significant difference in the primary outcome of exacerbation rates over 12 months. We observed an increase in normative adherence levels in a disease where adherence levels are low. The magnitude of the increase in adherence may not have been large enough to affect exacerbations.

Future work

Given the non-significant difference in the primary outcome, further research is required to explore why an increase in objective normative adherence did not reduce exacerbations and to develop interventions that reduce exacerbations.

Trial registration

Work package 3.1: Current Controlled Trials ISRCTN13076797. Work packages 3.2 and 3.3: Current Controlled Trials ISRCTN55504164.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 9, No. 11. See the NIHR Journals Library website for further project information.

Self-management intervention to reduce pulmonary exacerbations by supporting treatment adherence in adults with cystic fibrosis: a randomised controlled trial

Introduction

Recurrent pulmonary exacerbations lead to progressive lung damage in cystic fibrosis (CF). Inhaled medications (mucoactive agents and antibiotics) help prevent exacerbations, but objectively measured adherence is low. We investigated whether a multi-component (complex) self-management intervention to support adherence would reduce exacerbation rates over 12 months.

Methods

Between October 2017 and May 2018, adults with CF (aged ≥16 years; 19 UK centres) were randomised to the intervention (data-logging nebulisers, a digital platform and behavioural change sessions with trained clinical interventionists) or usual care (data-logging nebulisers). Outcomes included pulmonary exacerbations (primary outcome), objectively measured adherence, body mass index (BMI), lung function (FEV₁) and Cystic Fibrosis Questionnaire-Revised (CFQ-R). Analyses were by intent to treat over 12 months.

Results

Among intervention (n=304) and usual care (n=303) participants (51% female, median age 31 years), 88% completed 12-month follow-up. Mean exacerbation rate was 1.63/year with intervention and 1.77/year with usual care (adjusted ratio 0.96; 95% CI 0.83 to 1.12; p=0.64). Adjusted mean differences (95% CI) were in favour of the intervention versus usual care for objectively measured adherence (9.5% (8.6% to 10.4%)) and BMI (0.3 (0.1 to 0.6) kg/m²), with no difference for %FEV₁ (1.4 (−0.2 to 3.0)). Seven CFQ-R subscales showed no between-group difference, but treatment burden reduced for the intervention (3.9 (1.2 to 6.7) points). No intervention-related serious adverse events occurred.

Conclusions

While pulmonary exacerbations and FEV₁ did not show statistically significant differences, the intervention achieved higher objectively measured adherence versus usual care. The adherence difference might be inadequate to influence exacerbations, though higher BMI and lower perceived CF treatment burden were observed.

A multi-centre, randomized, controlled trial on coaching and telemonitoring in patients with cystic fibrosis: conneCT CF

Background

The extend of lung disease remains the most important prognostic factor for survival in patients with cystic fibrosis (CF), and lack of adherence is the main reason for treatment failure. Early detection of deterioration in lung function and optimising adherence are therefore crucial in CF care. We implement a randomized controlled trial to evaluate efficacy of telemonitoring of adherence, lung function, and health condition in combination with behavior change interventions using innovative digital technologies.

Methods

This is a multi-centre, randomized, controlled, non-blinded trial aiming to include 402 patients ≥ 12 years-of-age with CF. A standard-of-care arm is compared to an arm receiving objective, continuous monitoring of adherence to inhalation therapies, weekly home spirometry using electronic devices with data transmission to patients and caring physicians combined with video-conferencing, a self-management app and professional telephone coaching. The duration of the intervention phase is 18 months. The primary endpoint is time to the first protocol-defined pulmonary exacerbation. Secondary outcome measures include number of and time between pulmonary exacerbations, adherence to inhalation therapy, changes in forced expiratory volume in 1 s from baseline, number of hospital admissions, and changes in health-related quality of life. CF-associated medical treatment and care, and health care related costs will be assessed by explorative analysis in both arms.

Discussion

This study offers the opportunity to evaluate the effect of adherence interventions using telemedicine capable devices on adherence and lung health, possibly paving the way for implementation of telemedicine in routine care for patients with CF.

Trial registration: This study has been registered with the German Clinical Trials Register (Identifier: DRKS00024642, date of registration 01 Mar 2021, URL: https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00024642).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01500-y.

Development of an intervention to increase adherence to nebuliser treatment in adults with cystic fibrosis: CFHealthHub

BACKGROUND

Cystic fibrosis (CF) is a life-limiting genetic condition in which daily therapies to maintain lung health are critical, yet treatment adherence is low. Previous interventions to increase adherence have been largely unsuccessful and this is likely due to a lack of focus on behavioural evidence and theory alongside input from people with CF. This intervention is based on a digital platform that collects and displays objective nebuliser adherence data. The purpose of this paper is to identify the specific components of an intervention to increase and maintain adherence to nebuliser treatments in adults with CF with a focus on reducing effort and treatment burden.

METHODS

Intervention development was informed by the Behaviour Change Wheel (BCW) and person-based approach (PBA). A multidisciplinary team conducted qualitative research to inform a needs analysis, selected, and refined intervention components and methods of delivery, mapped adherence-related barriers and facilitators, associated intervention functions and behaviour change techniques, and utilised iterative feedback to develop and refine content and processes.

RESULTS

Results indicated that people with CF need to understand their treatment, be able to monitor adherence, have treatment goals and feedback and confidence in their ability to adhere, have a treatment plan to develop habits for treatment, and be able to solve problems around treatment adherence. Behaviour change techniques were selected to address each of these needs and were incorporated into the digital intervention developed iteratively, alongside a manual and training for health professionals. Feedback from people with CF and clinicians helped to refine the intervention which could be tailored to individual patient needs.

CONCLUSIONS

The intervention development process is underpinned by a strong theoretical framework and evidence base and was developed by a multidisciplinary team with a range of skills and expertise integrated with substantial input from patients and clinicians. This multifaceted development strategy has ensured that the intervention is usable and acceptable to people with CF and clinicians, providing the best chance of success in supporting people with CF with different needs to increase and maintain their adherence. The intervention is being tested in a randomised controlled trial across 19 UK sites.

Supporting medication adherence for adults with cystic fibrosis: a randomised feasibility study

BACKGROUND

Preventative medication reduces hospitalisations in people with cystic fibrosis (PWCF) but adherence is poor. We assessed the feasibility of a randomised controlled trial of a complex intervention, which combines display of real time adherence data and behaviour change techniques.

METHODS

Design: Pilot, open-label, parallel-group RCT with concurrent semi-structured interviews.

PARTICIPANTS

PWCF at two Cystic Fibrosis (CF) units. Eligible: aged 16 or older; on the CF registry. Ineligible: post-lung transplant or on the active list; unable to consent; using dry powder inhalers.

INTERVENTIONS

Central randomisation on a 1:1 allocation to: (1) intervention, linking nebuliser use with data recording and transfer capability to a software platform, and behavioural strategies to support self-management delivered by trained interventionists (n = 32); or, (2) control, typically face-to-face meetings every 3 months with CF team (n = 32).

OUTCOMES

RCT feasibility defined as: recruitment of ≥ 48 participants (75% of target) in four months (pilot primary outcome); valid exacerbation data available for ≥ 85% of those randomised (future RCT primary outcome); change in % medication adherence; FEV1 percent predicted (key secondaries in future RCT); and perceptions of trial procedures, in semi-structured interviews with intervention (n = 14) and control (n = 5) participants, interventionists (n = 3) and CF team members (n = 5).

RESULTS

The pilot trial recruited to target, randomising 33 to intervention and 31 to control in the four-month period, June-September 2016. At study completion (30th April 2017), 60 (94%; Intervention = 32, Control =28) participants contributed good quality exacerbation data (intervention: 35 exacerbations; control: 25 exacerbation). The mean change in adherence and baseline-adjusted FEV1 percent predicted were higher in the intervention arm by 10% (95% CI: -5.2 to 25.2) and 5% (95% CI -2 to 12%) respectively. Five serious adverse events occurred, none related to the intervention. The mean change in adherence was 10% (95% CI: -5.2 to 25.2), greater in the intervention arm. Interventionists delivered insufficient numbers of review sessions due to concentration on participant recruitment. This left interventionists insufficient time for key intervention procedures. A total of 10 key changes that were made to RCT procedures are summarised.

CONCLUSIONS

With improved research processes and lower monthly participant recruitment targets, a full-scale trial is feasible.

TRIAL REGISTRATION

ISRCTN13076797 . Prospectively registered on 07/06/2016.

Role of habit in treatment adherence among adults with cystic fibrosis

Among adults with cystic fibrosis (CF), medication adherence is low and reasons for low adherence are poorly understood. Our previous exploratory study showed that stronger 'habit' (ie, automatically experiencing an urge to use a nebuliser) was associated with higher nebuliser adherence. We performed a secondary analysis of pilot trial data (n=61) to replicate the earlier study and determine whether habit-adherence association exists in other cohorts of adults with CF. In this study, high adherers also reported stronger habit compared with low adherers. Habit may be a promising target for self-management interventions. TRIAL REGISTRATION NUMBER: ACtiF pilot, ISRCTN13076797.

Understanding Pseudomonas status among adults with cystic fibrosis: a real-world comparison of the Leeds criteria against clinicians' decision

Pseudomonas aeruginosa status influences cystic fibrosis (CF) clinical management but no 'gold standard' definition exists. The Leeds criteria are commonly used but may lack sensitivity for chronic P. aeruginosa. We compared clinicians' decision with the Leeds criteria in three adult CF centres. Two independent prospective datasets (Sheffield dataset, n = 185 adults; ACtiF pilot dataset, n = 62 adults from two different centres) were analysed. Clinicians involved in deciding P. aeruginosa status were blinded to the study objectives. Clinicians considered more adults with CF to have chronic P. aeruginosa infection compared to the Leeds criteria. This was more so for the Sheffield dataset (106/185, 57.3% with clinicians' decision vs. 80/185, 43.2% with the Leeds criteria; kappa coefficient between these two methods 0.72) compared to the ACtiF pilot dataset (34/62, 54.8% with clinicians' decision vs. 30/62, 48.4% with the Leeds criteria; kappa coefficient between these two methods 0.82). However, clinicians across different centres were relatively consistent once age and severity of lung disease, as indicated by the type of respiratory samples provided, were taken into account. Agreement in P. aeruginosa status was similar for both datasets among adults who predominantly provided sputum samples (kappa coefficient 0.78) or adults > 25 years old (kappa coefficient 0.82). Across three different centres, clinicians did not always agree with the Leeds criteria and tended to consider the Leeds criteria to lack sensitivity. Where disagreement occurred, clinicians tended to diagnose chronic P. aeruginosa infection because other relevant information was considered. These results suggest that a better definition for chronic P. aeruginosa might be developed by using consensus methods to move beyond a definition wholly dependent on standard microbiological results.

Rescue therapy within the UK Cystic Fibrosis Registry: An exploration of predictors of intravenous antibiotic use amongst adults with CF

Background and objective

Intravenous (i.v.) antibiotics are needed for rescue when preventative therapy fails to achieve stability among adults with cystic fibrosis (CF). Understanding the distribution of i.v. days can provide insight into the care that adults with CF need. We aim to determine the baseline characteristics that are associated with higher i.v. use, in particular to test the hypothesis that prior‐year i.v. use is associated with future‐year i.v. use.

Methods

This is a cross‐sectional analysis of the 2013–2014 UK CF registry data. Stepwise logistic regression was performed using current‐year i.v. days as the dependent variable, and demographic variables including prior‐year i.v. days as the covariates. Based on these results, study sample was divided into clinically meaningful subgroups using analysis similar to tree‐based method.

Results

Data were available for 4269 adults in 2013 and 4644 adults in 2014. Prior‐year i.v. use was the strongest predictor for current‐year i.v. use followed by forced expiratory volume in 1 s (FEV₁). Adults with high prior‐year i.v. use (>14 days) continued to require high levels of i.v., regardless of FEV₁. Those with high prior‐year i.v. use and FEV₁ ≥70% had higher current‐year i.v. days compared to adults with low prior‐year i.v. use and FEV₁ <40% (28 days, interquartile range (IQR): 11–41 days vs 14 days, IQR: 0–28 days; Mann–Whitney P‐value <0.001 in 2013).

Conclusion

CF people with prior high levels of rescue often continue to need high levels of rescue even if they have good FEV₁. The reasons for this require further investigations.

Intravenous (i.v.) antibiotic is an important treatment option in cystic fibrosis and is also a marker of pulmonary exacerbations. Our study showed that previous‐year i.v. use is a strong predictor of current‐year i.v. use. This finding could help clinicians to identify people most at risk of future exacerbation.

An Early Health Economic Analysis of the Potential Cost Effectiveness of an Adherence Intervention to Improve Outcomes for Patients with Cystic Fibrosis

BACKGROUND

Cystic fibrosis (CF) negatively impacts upon health-related quality of life and survival. Adherence to nebulised treatments is low; improving adherence is hypothesised to reduce rates of exacerbation requiring intravenous antibiotics and lung function decline.

OBJECTIVE

A state transition model was developed to assess the cost effectiveness of an intervention aimed at increasing patient adherence to nebulised and inhaled antibiotics compared with current CF care, in advance of the forthcoming CFHealthHub randomised controlled trial (RCT).

METHODS

The model estimated the costs and health outcomes for each option from the perspective of the UK National Health Service and Personal Social Services over a lifetime horizon. Health gains were valued in terms of quality-adjusted life-years (QALYs) gained. Forced expiratory volume in 1 second (FEV₁) trajectories were predicted over three lung function strata: (1) FEV₁ ≥70%, (2) FEV₁ 40-69% and (3) FEV₁ <40%. Additional states were included to represent 'post-lung transplantation' and 'dead'. The model was populated using CF Registry data, literature and expert opinion. Costs were presented at 2016 values. Uncertainty was assessed using deterministic and probabilistic sensitivity analyses.

RESULTS

If effective, the adherence intervention is expected to produce an additional 0.19 QALYs and cost savings of £64,078 per patient. Across all analyses, the intervention dominated current care. Over a 5-year period, the intervention is expected to generate cost savings of £49.5 million for the estimated 2979 patients with CF with Pseudomonas aeruginosa currently aged ≥16 years in the UK. If applied to a broader population of adult patients with CF receiving any nebulised therapy, the expected savings could be considerably greater.

CONCLUSIONS

If effective, the adherence intervention is expected to produce additional health gains at a lower cost than current CF care. However, the economic analysis should be revisited upon completion of the full RCT. More generally, the analysis suggests that considerable gains could be accrued through the implementation of adherence interventions that shift care from expensive hospital-based rescue to community-based prevention.

An empirical method to cluster objective nebulizer adherence data among adults with cystic fibrosis

BACKGROUND

The purpose of using preventative inhaled treatments in cystic fibrosis is to improve health outcomes. Therefore, understanding the relationship between adherence to treatment and health outcome is crucial. Temporal variability, as well as absolute magnitude of adherence affects health outcomes, and there is likely to be a threshold effect in the relationship between adherence and outcomes. We therefore propose a pragmatic algorithm-based clustering method of objective nebulizer adherence data to better understand this relationship, and potentially, to guide clinical decisions.

METHODS TO CLUSTER ADHERENCE DATA

This clustering method consists of three related steps. The first step is to split adherence data for the previous 12 months into four 3-monthly sections. The second step is to calculate mean adherence for each section and to score the section based on mean adherence. The third step is to aggregate the individual scores to determine the final cluster ("cluster 1" = very low adherence; "cluster 2" = low adherence; "cluster 3" = moderate adherence; "cluster 4" = high adherence), and taking into account adherence trend as represented by sequential individual scores. The individual scores should be displayed along with the final cluster for clinicians to fully understand the adherence data.

THREE ILLUSTRATIVE CASES

We present three cases to illustrate the use of the proposed clustering method.

CONCLUSION

This pragmatic clustering method can deal with adherence data of variable duration (ie, can be used even if 12 months' worth of data are unavailable) and can cluster adherence data in real time. Empirical support for some of the clustering parameters is not yet available, but the suggested classifications provide a structure to investigate parameters in future prospective datasets in which there are accurate measurements of nebulizer adherence and health outcomes.