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.

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.

Duration of intravenous antibiotic therapy in people with cystic fibrosis.

BACKGROUND: Progressive lung damage from recurrent exacerbations is the major cause of mortality and morbidity in cystic fibrosis. Life expectancy of people with cystic fibrosis has increased dramatically in the last 40 years. One of the major reasons for this increase is the mounting use of antibiotics to treat chest exacerbations caused by bacterial infections. The optimal duration of intravenous antibiotic therapy is not clearly defined. Individuals usually receive intravenous antibiotics for 14 days, but treatment may range from 10 to 21 days. A shorter duration of antibiotic treatment risks inadequate clearance of infection which could lead to further lung damage. Prolonged courses of intravenous antibiotics are expensive and inconvenient. The risk of systemic side effects such as allergic reactions to antibiotics also increases with prolonged courses and the use of aminoglycosides requires frequent monitoring to minimise some of their side effects. However, some organisms which infect people with cystic fibrosis are known to be multi-resistant to antibiotics, and may require a longer course of treatment. This is an update of previously published reviews. OBJECTIVES: To assess the optimal duration of intravenous antibiotic therapy for treating chest exacerbations in people with cystic fibrosis. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic database searches, handsearches of relevant journals, abstract books and conference proceedings. Most recent search of the Group's Cystic Fibrosis Trials Register: 30 May 2019.We also searched online trials registries. Most recent search of the ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) portal: 06 January 2019. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials comparing different durations of intravenous antibiotic courses for acute respiratory exacerbations in people with CF, either with the same drugs at the same dosage, the same drugs at a different dosage or frequency or different antibiotics altogether, including studies with additional therapeutic agents. DATA COLLECTION AND ANALYSIS: No eligible trials were identified for inclusion. A trial looking at the standardised treatment of pulmonary exacerbations is currently ongoing and will be included when the results are published.  MAIN RESULTS: No eligible trials were included. AUTHORS' CONCLUSIONS: There are no clear guidelines on the optimum duration of intravenous antibiotic treatment. Duration of treatment is currently based on unit policies and response to treatment. Shorter duration of treatment should improve quality of life and adherence, result in a reduced incidence of drug reactions and be less costly. However, the shorter duration may not be sufficient to clear a chest infection and may result in an early recurrence of an exacerbation. This systematic review identifies the need for a multicentre, randomised controlled trial comparing different durations of intravenous antibiotic treatment as it has important clinical and financial implications. The currently ongoing STOP2 trial is expected to provide some guidance on these questions when published.

Understanding patient activation and adherence to nebuliser treatment in adults with cystic fibrosis: responses to the UK version of PAM-13 and a think aloud study.

BACKGROUND: Patient activation refers to patients' knowledge, skills, and confidence in self-managing health conditions. In large cross-sectional studies, individuals with higher patient activation are observed to have better health outcomes with the assumption that they are more engaged in health self-management. However, the association between patient activation and objectively measured self-care indicators in individuals can be inconsistent. This research investigated the role of patient activation as measured by the UK Patient Activation Measure (PAM-13) in adults with Cystic Fibrosis (CF). The aims were twofold: to explore how adults with CF interpret and respond to the PAM-13; and to investigate the association between PAM-13 and objectively measured nebuliser adherence in UK adults with CF. METHODS: This article describes two studies which examined the PAM-13 from different perspectives. Study 1 comprised 'think aloud' interviews with 15 adults with CF. The data were analysed using an a priori coding framework. Study 2 examined the association between PAM-13 and objectively measured nebuliser adherence in 57 adults with CF. RESULTS: Study 1 showed that adults with CF encountered several difficulties while completing the PAM-13. The difficulties were related to understanding how to interpret aspects of CF in order to respond (i.e., control over the condition, ability to exercise) and item wording. Some adults with CF responded to the PAM-13 in an optimistic way in relation to what they thought they should do rather than what they actually do. These findings were echoed by the results of Study 2, which showed that PAM-13 scores were not significantly correlated with objective medication adherence in a different sample. This article synthesises the results of both studies, providing insights into influences and associations of patient activation as measured by the UK PAM-13 in adults with CF. CONCLUSIONS: There were some significant difficulties created by the wording of the UK PAM-13 for adults with CF. This may partly explain the finding that PAM-13 scores were not related to objectively measured nebuliser adherence in this study. The UK PAM-13 would benefit from further research to verify its validity and reliability in different patient populations against objective measures of behaviour rather than simply self-report.

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.

Why sample size estimates?

Sample size estimates are critical to the planning and interpretation of clinical studies, whether they are descriptive or analytical. Too small a sample size will result in imprecise estimates in a descriptive study and failure to achieve 'statistical significance' in an analytic or comparative study. Here we discuss what both researchers and readers should understand about the reasons for sample size estimates, how they are done and how achieving or not achieving the desired sample size can affect the interpretation of the outcomes.

What is an ROC curve?

The paper by Body et al is concerned with the evaluation of decision aids, which can be used to identify potential acute coronary syndromes (ACS) in the ED. The authors previously developed the Manchester Acute Coronary Syndromes model (MACS) decision aid, which uses several clinical variables and two biomarkers to 'rule in' and 'rule out' ACS. However, one of the two biomarkers (heart-type fatty acid bindingprotein, H-FABP) is not widely used so a revised decision aid has been developed (Troponin-only Manchester Acute Coronary Syndromes, T-MACS), which include a single biomarker hs-cTnT. In this issue, the authors show how they derive a revised decision aid and describe its performance in a number of independent diagnostic cohort studies. Decision aids (as well as other types of 'diagnostic tests') are often evaluated in terms of diagnostic testing parameters such as the area under the receiver operating characteristic (ROC) curve, sensitivity and specificity. In this article, we explain how the ROC analysis is conducted and why it is an essential step towards developing a test with the desirable levels of sensitivity and specificity.

Moving cystic fibrosis care from rescue to prevention by embedding adherence measurement in routine care.

Cystic fibrosis [CF] is a chronic disease in which preventative treatment with nebulised antibiotics can reduce pulmonary exacerbations that otherwise require rescue therapy. However, adherence is low. Making adherence to maintenance treatment visible is a crucial step towards improving adherence. In this article, we discuss how adherence data can be used to support Quality Improvement in CF through behaviour change in both people with cystic fibrosis and their clinical teams.

Development of data processing algorithm to calculate adherence for adults with cystic fibrosis using inhaled therapy - a multi-center observational study within the CFHealthHub learning health system.

OBJECTIVES: To develop a robust algorithm to accurately calculate 'daily complete dose counts' for inhaled medicines, used in percent adherence calculations, from electronically-captured nebulizer data within the CFHealthHub Learning Health System. METHODS: A multi-center, cross-sectional study involved participants and clinicians reviewing real-world inhaled medicine usage records and triangulating them with objective nebulizer data to establish a consensus on 'daily complete dose counts.' An algorithm, which used only objective nebulizer data, was then developed using a derivation dataset and evaluated using internal validation dataset. The agreement and accuracy between the algorithm-derived and consensus-derived 'daily complete dose counts' was examined, with the consensus-derived count as the reference standard. RESULTS: Twelve people with CF participated. The algorithm derived a 'daily complete dose count' by screening out 'invalid' doses (those <60s in duration or run in cleaning mode), combining all doses starting within 120s of each other, and then screening out all doses with duration < 480s which were interrupted by power supply failure. The kappa co-efficient was 0.85 (0.71-0.91) in the derivation and 0.86 (0.77-0.94) in the validation dataset. CONCLUSIONS: The algorithm demonstrated strong agreement with the participant-clinician consensus, enhancing confidence in CFHealthHub data. Publishingdata processing methods can encourage trust in digital endpoints and serve as an exemplar for other projects.

Idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis is a progressive lung disease that carries a poor prognosis and for which there are no effective therapies. Although the excessive deposition of extracellular matrix, combined with evidence of recurrent injury to the alveolar epithelium, are well-described there is a pressing need to understand these processes better at a molecular level and thus to identify potential therapeutic targets in this intractable disease. This review considers some recent advances published in Thorax and elsewhere that have improved our understanding of the pathophysiology of idiopathic pulmonary fibrosis, using data both from human cells and tissue and from animal models of pulmonary fibrosis. The studies particularly address the fate of the alveolar epithelial cell and mechanisms of fibrogenesis, and identify mechanistic pathways shared with co-existing conditions such as lung cancer and pulmonary hypertension. The concepts of physiological biomarkers of disease progression and prognosis are also discussed.

Using a learning health system to understand the mismatch between medicines supply and actual medicines use among adults with cystic fibrosis.

BACKGROUND: Studies in separate cohorts suggest possible discrepancies between inhaled medicines supplied (median 50-60%) and medicines used (median 30-40%). We performed the first study that directly compares CF medicine supply against use to identify the cost of excess medicines supply. METHODS: This cross-sectional study included participants from 12 UK adult centres with ≥1 year of continuous adherence data from data-logging nebulisers. Medicine supply was measured as medication possession ratio (MPR) for a 1-year period from the first suitable supply date. Medicine use was measured as electronic data capture (EDC) adherence over the same period. The cost of excess medicines was calculated as whole excess box(es) supplied after accounting for the discrepancy between EDC adherence and MPR with 20% contingency. RESULTS: Among 275 participants, 133 (48.4%) were females and mean age was 30 years (95% CI 29-31 years). Median EDC adherence was 57% (IQR 23-86%), median MPR was 74% (IQR 46-96%) and the discrepancy between measures was median 14% (IQR 2-29%). Even with 20% contingency, mean potential cost of excess medicines was £1,124 (95% CI £855-1,394), ranging from £183 (95% CI £29-338) for EDC adherence ≥80% to £2,017 (95% CI £1,507-2,526) for EDC adherence <50%. CONCLUSIONS: This study provides a conservative estimate of excess inhaled medicines supply cost among adults with CF in the UK. The excess supply cost was highest among those with lowest EDC adherence, highlighting the importance of adherence support and supplying medicine according to actual use. MPR provides information about medicine supply but over-estimates actual medicine use.

Prospectively predicting Pseudomonas aeruginosa infection/s using routine data from the UK cystic fibrosis register.

RATIONALE AND AIMS: Lung health of people with cystic fibrosis (PwCF) can be preserved by daily use of inhaled therapy. Adherence to inhaled therapy, therefore, provides an important process measure to understand the success of care and can be used as a quality indicator. Defining adherence is problematic, however, since the number of prescribed treatments varies considerably between PwCF. The problem is less pronounced among those with Pseudomonas aeruginosa (PA), for whom at least three daily doses of nebulized therapy should be prescribed and who thus constitute a more homogeneous group. The UK CF Registry provides routine data on PA status, but data are only available 12 months after collection. In this study, we aim to prospectively identify contemporary PA status from historic registry data. METHOD: UK CF Registry data from 2011 to 2015 for PwCF aged ≥16 was used to determine a pragmatic prediction rule for identifying contemporary PA status using historic registry data. Accuracy of three different prediction rules was assessed using the positive predictive value (PPV). The number and proportion of adults predicted to have PA infection were determined overall and per center for the selected prediction rule. Known characteristics linked to PA status were explored to ensure the robustness of the prediction rule. RESULTS: Having CF Registry defined chronic PA status in the two previous years is the selected definition to predict a patient will have PA infection within the current year (population-level PPV = 96%-97%, centre level PPV = 85%-100%). This approach provides a subset of data between 1852 and 1872 patients overall and a range of 8 to 279 patients per center. CONCLUSION: Historic registry data can be used to contemporaneously identify a subgroup of patients with chronic PA. Since this patient group has a narrower treatment schedule, this can facilitate a better benchmarking of adherence across centers.

A comparison of the CFHH criteria against the Leeds criteria in determining the Pseudomonas aeruginosa status among adults with cystic fibrosis.

BACKGROUND: Pseudomonas aeruginosa (PA) status influences management decisions in cystic fibrosis (CF) but diagnostic approaches vary. We evaluated the ability of the CFHealthHub (CFHH) criteria, which consist of two major and four minor statements, in diagnosing chronic PA infection among adults with CF. METHODS: In this retrospective cross-sectional analysis, we compared the CFHH criteria against the Leeds criteria. Data were collected between 1st January and 31st December 2016 from all adults with CF receiving care at Sheffield, excluding those with lung transplantation (n = 7) or on ivacaftor (n = 13). The CFHH criteria PA status were cross-tabulated against the Leeds criteria, and clinical outcomes between chronic PA vs non chronic PA for both criteria were compared. RESULTS: This analysis included 186 adults with CF (90 females, median age 27 years, median baseline FEV1 78.5%). The CFHH criteria diagnosed more cases of chronic PA (116/186, 62.4% vs 79/186, 42.5%), and 37/107 cases of non-chronic PA according to the Leeds criteria were deemed chronic PA by the CFHH criteria. The magnitude of difference in %FEV1 decline between chronic PA vs non chronic PA was slightly greater for the CFHH criteria (-0.6%, 95% CI -1.8 to 0.6%) compared to the Leeds criteria (-0.2%, 95% CI -1.3 to 1.0%). CONCLUSIONS: The CFHH criteria detected more chronic PA cases yet still retained similar levels of discrimination for health outcomes in comparison to the Leeds criteria. These findings provide preliminary evidence for the validity of the CFHH criteria among adults with CF.

Understanding FEV1 for the purpose of cystic fibrosis registry comparisons: Does bias in annual review FEV1 affect between-centre comparison within the UK? An analysis of registry data.

RATIONALE, AIMS, AND OBJECTIVE: We previously demonstrated that annual review %FEV1 underestimates lung health of adults with CF compared with %FEV1 captured during periods of clinical stability. This has implications in the comparisons against registries with encounter-based FEV1 , such as the United States. It is uncertain whether this bias affects between-centre comparison within the United Kingdom. Previous funnel plot analyses have identified variation in annual review %FEV1 according to centre size; hence, we investigated whether paired differences between annual review and best %FEV1 also vary according to centre size. METHODS: This registry analysis included 18 adult CF centres in the United Kingdom with ≥80% completeness for best FEV1 data in 2014. Mean discrepancy between annual review and best %FEV1 is a surrogate for the extent by which annual review %FEV1 underestimates lung health, and was plotted against centre size. A local polynomial regression (LOESS) curve was used to explore the relationship between the two variables. An appropriate model is fitted based on the LOESS curve to determine the strength of relationship between discrepancies in %FEV1 and centre size. RESULTS: There is an inverted U-shaped relationship between mean discrepancies in %FEV1 and centre size. A regression of the paired mean difference in %FEV1 against centre size showed a significant improvement in the goodness of fit for a quadratic model (R2  = 23.8% for a quadratic model compared with 0.4% for a linear one; P = 0.048 for the quadratic term). CONCLUSIONS: Annual review %FEV1 underestimated lung health of adults from small and large centres in the United Kingdom to a greater extent compared with medium-sized centres. A plot of %FEV1 against centre size (eg, funnel plot comparison) would be affected by systematic bias in annual review %FEV1 . Therefore, annual review %FEV1 is an unreliable metric to compare health outcomes of adult CF centres within the United Kingdom.

Exploring the implications of different approaches to estimate centre-level adherence using objective adherence data in an adult cystic fibrosis centre - a retrospective observational study.

BACKGROUND: Accurate centre-level medication adherence measurement allows identification of highly performing CF centres, drives shared learning and informs quality improvement. Self-reported adherence is unreliable but data-logging nebulisers can capture objective data. However, adherence levels in current literature are limited by the use of agreed prescriptions and convenience sampling. In this single-centre retrospective study, we quantified the differences in centre-level adherence with different methods of calculating adherence (unadjusted vs normative adherence) and different data sampling frames (convenience sampling vs including difficult to obtain data). METHODS: Adherence data were objectively captured using I-neb® from 2013-2016 in Sheffield Adult CF Centre. Adults on non data-logging devices, on ivacaftor or with previous lung transplantation were excluded. Adherence was calculated based on agreed regimen ('unadjusted adherence') or minimum required regimen ('normative adherence'). I-nebs® not brought to clinic were downloaded during home visits. Adults not on any inhaled therapy but with chronic Pseudomonas aeruginosa infection were included by counting their adherence as "0". RESULTS: Of the 131 included adults, 126 provided I-neb® data. Calculating unadjusted adherence from I-nebs® brought to clinics resulted in the highest centre-level adherence (median 41.8% in 2013). Median adherence reduced after sequentially accounting for minimum required regimen (40.0% in 2013), I-nebs® not brought to clinics (32.9% in 2013) and adults not on any inhaled therapy (31.0% in 2013). CONCLUSIONS: Different approaches of calculating adherence produced different adherence levels. Adherence levels based only on agreed regimen among adults who readily brought their nebulisers to clinics can over-estimate the effective adherence of CF centres.

Making the invisible visible: the availability and desirability of adherence data in routine CF care- findings from a national questionnaire survey.

Background: Inhaled medications for cystic fibrosis (CF) are effective but adherence is low. Clinicians find it difficult to estimate how much treatment people with CF (PWCF) take, whilst objective adherence measurement demonstrates that patients are poorly calibrated with a tendency to over-estimate actual adherence. The diagnostic approach to a PWCF with deteriorating clinical status and very low adherence is likely to be different to the approach to a deteriorating patient with optimal adherence. Access to objective adherence data in routine consultations could help to overcome diagnostic challenges for clinicians and people with CF. Attitudes of clinicians to the use and importance of routinely available adherence data is unknown. Methods: We conducted an online questionnaire survey with UK CF centres. We asked five questions relating to the current use and perception of objective measurements of adherence in routine care. Results: A total of eight CF centres completed the questionnaire. Few of the responding centres have adherence data readily available in routine clinics (13% of centres use medicines possession ratio; of centres with access to I-nebs® it was estimated that 17% of patients had I-neb data regularly available in clinics). All centres considered the availability of objectively measured adherence data to be important. Respondents identified that systems developed to provide adherence data in clinical practice must provide data to both clinicians and patients that is readily understood and easy to use. Conclusions: Centres perceived the availability of adherence data in routine care to be important but objective measures of adherence is rarely available at present.

A pragmatic behavior-based habit index for adherence to nebulized treatments among adults with cystic fibrosis.

BACKGROUND: Habit, a psychological process that automatically generates urges to perform a behavior in associated settings, is potentially an important determinant of medication adherence. Habit is challenging to measure because, as a psychological construct, it cannot be directly observed. We describe a method of using routinely available objective adherence data from electronic data capture (EDC) to generate a behavior-based index of adherence habit and demonstrate how this index can be applied. METHODS TO GENERATE THE HABIT INDEX: Our proposed habit index is a "frequency in context" measure. It estimates habit as a multiplicative product of behavior frequency (generated from weekly percentage adherence) and context stability (inferred from time of nebulizer use). Although different timescales can be used, we chose to generate weekly habit scores since we believe that this is the most granular level at which context stability can be reasonably calculated. AN APPLICATION OF THE HABIT INDEX: A hallmark of habit is to predict future behavior, hence we used time series method to cross-correlate the habit index with nebulizer adherence in the subsequent week among 123 adults with cystic fibrosis (52, 42.3% female; median age 25 years) over a median duration of 153 weeks (IQR 74-198 weeks). The mean cross-correlation coefficient (R) between the habit index and subsequent adherence was 0.40 (95% CI 0.36-0.44). Adjusting for current adherence, the unstandardized regression coefficient (B) for the habit index was 0.30 (95% CI -1.04 to 1.65). CONCLUSION: We have described a pragmatic method to infer "habit" from adherence data routinely captured with EDC and provided proof-of-principle evidence regarding the feasibility of this concept. The continuous stream of data from EDC allows the habit index to unobtrusively assess "habit" at various time points over prolonged periods, and hence the habit index may be applicable in habit formation studies.

Intravenous antibiotic use and exacerbation events in an adult cystic fibrosis centre: A prospective observational study.

INTRODUCTION: In CF, people with higher FEV1 are less aggressively treated with intravenous (IV) antibiotics, with resultant negative impact on their health outcomes. This could be entirely clinician-driven, but patient choice may also influence IV use. In this prospective observational study, we explored IV recommendations by clinicians and IV acceptance by adults with CF to understand how clinical presentations consistent with exacerbations resulted in IV use. METHODS: Clinical presentations consistent with exacerbations, IV recommendation by clinicians and IV acceptance by patients were prospectively identified for every adult with CF in Sheffield throughout 2016, excluding those who had lung transplantation (n = 7) or on ivacaftor (n = 13). Relevant demographic data, e.g. %FEV1, were extracted from medical records. Multi-level mixed-effects logistic regression models were used to compare IV recommendations vs non-recommendations for all clinical encounters, and IV acceptance vs non-acceptance for all IV recommendations. RESULTS: Among 186 adults (median age 27 years, median FEV1 78.5%), there were 434 exacerbation events and 318 IV use episodes following 1010 clinical encounters. Only 254 (58.5%) of exacerbations were IV treated. A diagnosis of exacerbation, higher number of symptoms and lower %FEV1 were independent predictors for IV recommendation by clinicians. Higher number of symptoms and lower %FEV1 were also independent predictors for IV acceptance by adults with CF. CONCLUSIONS: Lower IV use among adults with higher %FEV1 was influenced by both clinicians' and patients' decisions. Using IV antibiotics as an exacerbation surrogate could under-estimate exacerbation rates and conceal differential treatment decisions according to varying clinical characteristics.