The sputum microbiome and clinical outcomes in patients with bronchiectasis: a prospective observational study.

BACKGROUND: Infection is a key component of bronchiectasis pathophysiology. Characterisation of the microbiome offers a higher degree of sensitivity and resolution than does traditional culture methods. We aimed to evaluate the role of the microbiome in determining the risk of exacerbation and long-term outcomes, including all-cause mortality, in bronchiectasis. METHODS: We did a prospective observational cohort study of patients with bronchiectasis from eastern Scotland. Patients were enrolled from Sept 11, 2012, to Dec 21, 2015, and followed until Jan 8, 2019, for long-term outcomes. Patients were included if they were aged 18 years or older, and had a high-resolution CT-confirmed diagnosis of bronchiectasis and clinical symptoms consistent with the disease. Sputum samples were obtained when patients were clinically stable. Repeat sputum samples were taken at stable and exacerbation visits during follow-up. The V3-V4 region of the bacterial 16S rRNA gene was sequenced using the Illumina MiSeq platform. The dominant bacterial genus in each sample was assigned on the basis of a previously published method. Microbiome characteristics were analysed for their association with measures of clinical disease severity and long-term outcomes using PERMANOVA, random forest, and survival analyses. FINDINGS: Sequencing data were obtained from the sputum samples of 281 patients with bronchiectasis who were included in the stable baseline cohort. 49 (17%) of 281 patients provided more than one sample when clinically stable and were included in the longitudinal analysis. 64 (23%) patients provided both stable and exacerbation samples. In both stable bronchiectasis and during exacerbations, a sputum microbiome dominated by Proteobacteria and Firmicutes was observed. Individual patients' microbiome profiles were relatively stable over time, during exacerbations and at disease stability. Lower microbiome diversity, measured using the Shannon-Wiener diversity index, was associated with more severe bronchiectasis defined by the bronchiectasis severity index, lower FEV1, and more severe symptoms. Random forest analysis of baseline samples identified Pseudomonas, Enterobacteriaceae, and Stenotrophomonas as being associated with severe bronchiectasis (bronchiectasis severity index ≥9) and greater lung inflammation and Pseudomonas and Enterobacteriaceae with more frequent exacerbations. Patients in whom Pseudomonas was dominant (n=35) were at increased risk of all-cause mortality (hazard ratio 3·12, 95% CI 1·33-7·36; p=0·0091) and had more frequent exacerbations (incident rate ratio 1·69, 95% CI 1·07-2·67; p=0·024) during follow-up compared with patients with other dominant genera (n=246). INTERPRETATION: A reduction in microbiome diversity, particularly one associated with dominance of Pseudomonas, is associated with greater disease severity, higher frequency and severity of exacerbations, and higher risk of mortality. The microbiome might therefore identify subgroups of patients at increased risk of poor outcomes who could benefit from precision treatment strategies. Further research is required to identify the mechanisms of reduced microbiome diversity and to establish whether the microbiome can be therapeutically targeted. FUNDING: British Lung Foundation and European Respiratory Society EMBARC2 consortium.

Neutrophil extracellular traps, disease severity, and antibiotic response in bronchiectasis: an international, observational, multicohort study.

BACKGROUND: Bronchiectasis is predominantly a neutrophilic inflammatory disease. There are no established therapies that directly target neutrophilic inflammation because little is understood of the underlying mechanisms leading to severe disease. Neutrophil extracellular trap (NET) formation is a method of host defence that has been implicated in multiple inflammatory diseases. We aimed to investigate the role of NETs in disease severity and treatment response in bronchiectasis. METHODS: In this observational study, we did a series of UK and international studies to investigate the role of NETs in disease severity and treatment response in bronchiectasis. First, we used liquid chromatography-tandem mass spectrometry to identify proteomic biomarkers associated with disease severity, defined using the bronchiectasis severity index, in patients with bronchiectasis (n=40) in Dundee, UK. Second, we validated these biomarkers in two cohorts of patients with bronchiectasis, the first comprising 175 patients from the TAYBRIDGE study in the UK and the second comprising 275 patients from the BRIDGE cohort study from centres in Italy, Spain, and UK, using an immunoassay to measure NETs. Third, we investigated whether pathogenic bacteria had a role in NET concentrations in patients with severe bronchiectasis. In a separate study, we enrolled patients with acute exacerbations of bronchiectasis (n=20) in Dundee, treated with intravenous antibiotics for 14 days and proteomics were used to identify proteins associated with treatment response. Findings from this cohort were validated in an independent cohort of patients who were admitted to the same hospital (n=20). Fourth, to assess the potential use of macrolides to reduce NETs in patients with bronchiectasis, we examined two studies of long-term macrolide treatment, one in patients with bronchiectasis (n=52 from the UK) in which patients were given 250 mg of azithromycin three times a week for a year, and a post-hoc analysis of the Australian AMAZES trial in patients with asthma (n=47) who were given 500 mg of azithromycin 3 times per week for a year. FINDINGS: Sputum proteomics identified that NET-associated proteins were the most abundant and were the proteins most strongly associated with disease severity. This finding was validated in two observational cohorts, in which sputum NETs were associated with bronchiectasis severity index, quality of life, future risk of hospital admission, and mortality. In a subgroup of 20 patients with acute exacerbations, clinical response to intravenous antibiotic treatment was associated with successfully reducing NETs in sputum. Patients with Pseudomonas aeruginosa infection had a lessened proteomic and clinical response to intravenous antibiotic treatment compared with those without Pseudomonas infections, but responded to macrolide therapy. Treatment with low dose azithromycin was associated with a significant reduction in NETs in sputum over 12 months in both bronchiectasis and asthma. INTERPRETATION: We identified NETs as a key marker of disease severity and treatment response in bronchiectasis. These data support the concept of targeting neutrophilic inflammation with existing and novel therapies. FUNDING: Scottish Government, British Lung Foundation, and European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC).

The sputum microbiome, airway inflammation, and mortality in chronic obstructive pulmonary disease.

BACKGROUND: The sputum microbiome has a potential role in disease phenotyping and risk stratification in chronic obstructive pulmonary disease (COPD), but few large longitudinal cohort studies exist. OBJECTIVE: Our aim was to investigate the COPD sputum microbiome and its association with inflammatory phenotypes and mortality. METHODS: 16S ribosomal RNA gene sequencing was performed on sputum from 253 clinically stable COPD patients (4-year median follow-up). Samples were classified as Proteobacteria or Firmicutes (phylum level) and Haemophilus or Streptococcus (genus level) dominant. Alpha diversity was measured by using Shannon-Wiener diversity and Berger-Parker dominance indices. Survival was modeled by using Cox proportional hazards regression. A subset of 78 patients had label-free liquid chromatography with tandem mass spectrometry performed, with partial least square discriminant analysis integrating clinical, microbiome, and proteomics data. RESULTS: Proteobacteria dominance and lower diversity was associated with more severe COPD according to the Global Initiative for Chronic Obstructive Lung Disease classification system (P = .0015), more frequent exacerbations (P = .0042), blood eosinophil level less than or equal to 100 cells/µL (P < .0001), and lower FEV1 (P = .026). Blood eosinophil counts showed a positive relationship with percent of Firmicutes and Streptococcus and a negative association with percent Proteobacteria and Haemophilus. Proteobacteria dominance was associated with increased mortality compared with Firmicutes-dominated or balanced microbiome profiles (hazard ratio = 2.58; 95% CI = 1.43-4.66; P = .0017 and hazard ratio = 7.47; 95% CI = 1.02-54.86; P = .048, respectively). Integrated omics analysis showed significant associations between Proteobacteria dominance and the neutrophil activation pathway in sputum. CONCLUSION: The sputum microbiome is associated with clinical and inflammatory phenotypes in COPD. Reduced microbiome diversity, associated with Proteobacteria (predominantly Haemophilus) dominance, is associated with neutrophil-associated protein profiles and an increased risk of mortality.

Blood neutrophil counts are associated with exacerbation frequency and mortality in COPD.

BACKGROUND: Identifying patients with COPD at increased risk of poor outcomes is challenging due to disease heterogeneity. Potential biomarkers need to be readily available in real-life clinical practice. Blood eosinophil counts are widely studied but few studies have examined the prognostic value of blood neutrophil counts (BNC). METHODS: In a large population-based COPD registry in the East of Scotland (TARDIS: Tayside Allergic and Respiratory Disease Information System), BNC were compared to measures of disease severity and mortality for up to 15 years follow-up. Potential mechanisms of disease modification by BNC were explored in a nested microbiome substudy. RESULTS: 178,120 neutrophil counts were obtained from 7220 people (mean follow up 9 years) during stable disease periods. Median BNC was 5200cells/µL (IQR 4000-7000cells/µL). Mortality rates among the 34% of patients with elevated BNCs (defined as 6000-15000cells/µL) at the study start were 80% higher (14.0/100 person years v 7.8/100py, P < 0.001) than those with BNC in the normal range (2000-6000cells/µL). People with elevated BNC were more likely to be classified as GOLD D (46% v 33% P < 0.001), have more exacerbations (mean 2.3 v 1.3/year, P < 0.001), and were more likely to have severe exacerbations (13% vs. 5%, P < 0.001) in the following year. Eosinophil counts were much less predictive of these outcomes. In a sub-cohort (N = 276), patients with elevated BNC had increased relative abundance of Proteobacteria and reduced microbiome diversity. CONCLUSION: High BNC may provide a useful indicator of risk of exacerbations and mortality in COPD patients.

Estimates of the ongoing need for social distancing and control measures post-"lockdown" from trajectories of COVID-19 cases and mortality.

By 21 May 2020, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) had caused more than 5 million cases of coronavirus 2019 (COVID-19) across more than 200 countries. Most countries with significant outbreaks have introduced social distancing or "lockdown" measures to reduce viral transmission. So the key question now is when, how and to what extent these measures can be lifted.Publicly available data on daily numbers of newly confirmed cases and mortality were used to fit regression models estimating trajectories, doubling times and the reproduction number (R0) of the disease, before and under the control measures. These data ran up to 21 May 2020, and were sufficient for analysis in 89 countries.The estimates of R0 before lockdown based on these data were broadly consistent with those previously published: between 2.0 and 3.7 in the countries with the largest number of cases available for analysis (USA, Italy, Spain, France and UK). There was little evidence to suggest that the restrictions had reduced R far below 1 in many places, with France having the most rapid reductions: R0 0.76 (95% CI 0.72-0.82) based on cases, and 0.77 (95% CI 0.73-0.80) based on mortality.Intermittent lockdown has been proposed as a means of controlling the outbreak while allowing periods of increased freedom and economic activity. These data suggest that few countries could have even 1 week per month unrestricted without seeing resurgence of the epidemic. Similarly, restoring 20% of the activity that has been prevented by the lockdowns looks difficult to reconcile with preventing the resurgence of the disease in most countries.

Inhaled aztreonam improves symptoms of cough and sputum production in patients with bronchiectasis: a post hoc analysis of the AIR-BX studies.

INTRODUCTION: Inhaled antibiotics may improve symptom scores, but it is not known which specific symptoms improve with therapy. Item-level analysis of questionnaire data may allow us to identify which specific symptoms respond best to treatment. METHODS: Post hoc analysis of the AIR-BX1 studies and two trials of inhaled aztreonam versus placebo in bronchiectasis. Individual items from the quality of life bronchiectasis (QOL-B) respiratory symptom scale, were extracted as representing severity of nine distinct symptoms. Generalised linear models were used to evaluate changes in symptoms with treatment versus placebo from baseline to end of first on-treatment cycle and mixed models were used to evaluate changes across the full 16-week trial. RESULTS: Aztreonam improved cough (difference 0.22, 95% CI 0.08-0.37; p=0.002), sputum production (0.30, 95% CI 0.15-0.44; p<0.0001) and sputum colour (0.29, 95% CI 0.15-0.43; p<0.0001) versus placebo equating to a 20% improvement in cough and 25% improvement in sputum production and colour. Similar results were observed for cough, sputum production and sputum purulence across the trial duration (all p<0.05). Patients with higher sputum production and sputum colour scores had a greater response on the overall QOL-B (difference 4.82, 95% CI 1.12-8.53; p=0.011 for sputum production and 5.02, 95% CI 1.19-8.86; p=0.01 for sputum colour). In contrast, treating patients who had lower levels of bronchitic symptoms resulted in shorter time to next exacerbation (hazard ratio 1.83, 95% CI 1.02-3.28; p=0.042). CONCLUSION: Baseline bronchitic symptoms predict response to inhaled aztreonam in bronchiectasis. More sensitive tools to measure bronchitic symptoms may be useful to better identify inhaled antibiotic responders and to evaluate patient response to treatment.

Relationship between Symptoms, Exacerbations, and Treatment Response in Bronchiectasis.

Rationale: Bronchiectasis guidelines regard treatment to prevent exacerbation and treatment of daily symptoms as separate objectives.Objectives: We hypothesized that patients with greater symptoms would be at higher risk of exacerbations and therefore that a treatment aimed at reducing daily symptoms would also reduce exacerbations in highly symptomatic patients.Methods: Our study comprised an observational cohort of 333 patients from the East of Scotland (2012-2016). Either symptoms were modeled as a continuous variable or patients were classified as having high, moderate, or low symptom burden (>70, 40-70, and <40 using the St. George's Respiratory Questionnaire symptom score). The hypothesis that exacerbation reductions would only be evident in highly symptomatic patients was tested in a post hoc analysis of a randomized trial of inhaled dry powder mannitol (N = 461 patients).Measurements and Main Results: In the observational cohort, daily symptoms were a significant predictor of future exacerbations (rate ratio [RR], 1.10; 95% confidence interval [CI], 1.03-1.17; P = 0.005). Patients with higher symptom scores had higher exacerbation rates (RR, 1.74; 95% CI, 1.12-2.72; P = 0.01) over 12-month follow-up than those with lower symptoms. Inhaled mannitol treatment improved the time to first exacerbation (hazard ratio, 0.56; 95% CI, 0.40-0.77; P < 0.001), and the proportion of patients remaining exacerbation free for 12 months of treatment was higher in the mannitol group (32.7% vs. 14.6%; RR, 2.84; 95% CI, 1.40-5.76; P = 0.003), but only in highly symptomatic patients. In contrast, no benefit was evident in patients with lower symptom burden.Conclusions: Highly symptomatic patients have increased risk of exacerbations, and exacerbation benefit with inhaled mannitol was only evident in patients with high symptom burden.

Long-term macrolide antibiotics for the treatment of bronchiectasis in adults: an individual participant data meta-analysis.

BACKGROUND: Bronchiectasis guidelines recommend long-term macrolide treatment for patients with three or more exacerbations per year without Pseudomonas aeruginosa infection. Randomised controlled trials suggest that long-term macrolide treatment can prevent exacerbations in adult patients with bronchiectasis, but these individual studies have been too small to do meaningful subgroup analyses. We did a systematic review and individual patient data (IPD) meta-analysis to explore macrolide benefit in subpopulations, including those in which macrolide therapy is not currently recommended. METHODS: We searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, and Web of Science from Jan 1, 2000, to Sept 30, 2018, to identify double blind, randomised, placebo-controlled trials of macrolide antibiotics in adult patients with bronchiectasis. We applied no language restrictions. Randomised controlled trials were eligible if treatment was defined a priori as long term and had a primary or secondary outcome of bronchiectasis exacerbations. Studies in patients with cystic fibrosis bronchiectasis were excluded. The primary outcome of the meta-analysis was frequency of exacerbations requiring treatment with antibiotics. Secondary endpoints were time to first exacerbation, change in quality of life according to the St George's Respiratory Questionnaire (SGRQ), and change in FEV1. IPD meta-analysis was done using fixed effects models adjusting for age, sex, FEV1, and trial. We did prespecified subgroup analyses for each of the primary and secondary endpoints using one-step meta-analysis only. Subgroups were defined by age, sex, previous exacerbation frequency, smoking status, inhaled corticosteroid use at baseline, body-mass index at baseline, cause, C-reactive protein at baseline, baseline FEV1 percentage of predicted, SGRQ total score, and Pseudomonas aeruginosa in sputum culture at baseline. The meta-analysis is registered with the PROSPERO international register of systematic reviews, number CRD42018102908. FINDINGS: Of 234 identified studies, we included three randomised controlled trials, and IPD was obtained for 341 participants. Macrolide antibiotics reduced the frequency of exacerbations (adjusted incidence rate ratio [IRR] 0·49, 95% CI 0·36 to 0·66; p<0·0001). We also found that macrolide treatment improved the time to first exacerbation (adjusted hazard ratio 0·46, 0·34 to 0·61; p<0·0001) and was associated with improved quality of life measured by the SGRQ (mean improvement 2·93 points, 0·03 to 5·83; p=0·048). Macrolides were not associated with a significant improvement in FEV1 (67 mL at 1 year, -22 to 112; p=0·14). Effect estimates in prespecified subgroup analyses revealed a reduced frequency of exacerbations in all prespecified subgroups, including a high level of benefit in patients with P aeruginosa infection (IRR 0·36, 0·18-0·72; p=0·0044) and in patients with one to two exacerbations per year (0·37, 0·16-0·88; p=0·025). Studies were rated as low risk of bias across all domains. INTERPRETATION: Long-term macrolide treatment significantly reduces the frequency of exacerbations in patients with bronchiectasis, with similar benefits observed in all subgroups based on patient characteristics. This finding suggests that macrolides might be considered in patients in whom macrolides are not indicated according to the current guidelines, particularly if alternative approaches to reduce exacerbations have been unsuccessful. However, downsides of long-term macrolide treatment must also be taken into account. FUNDING: European Respiratory Society.

Airway Bacterial Load and Inhaled Antibiotic Response in Bronchiectasis.

Rationale: The principal underlying inhaled antibiotic treatment in bronchiectasis is that airway bacterial load drives inflammation, and therefore antibiotic treatment will reduce symptoms. Objectives: To determine the relationship between bacterial load and clinical outcomes, assess the stability of bacterial load over time, and test the hypothesis that response to inhaled antibiotics would be predicted by baseline bacterial load. Methods: We performed three studies. Studies 1 and 2 were prospective studies including adults with bronchiectasis. Study 3 was a post hoc analysis of a randomized trial of inhaled aztreonam. A priori patients were divided into low (<105 cfu/g), moderate (105-106 cfu/g), and high bacterial load (≥107 cfu/g) using quantitative sputum culture. Measurements and Main Results: Bacterial load was a stable trait associated with worse quality of life and more airway inflammation in studies 1, 2, and 3. In study 3, patients with high bacterial load showed an improvement in the primary endpoint (Quality of Life-Bronchiectasis-Respiratory Symptoms Score at Week 4) in favor of aztreonam (mean difference of 9.7 points; 95% confidence interval, 3.4-16.0; P = 0.003). The proportion of patients who achieved an increase above the minimum clinically important difference was higher in the aztreonam group at Week 4 (63% vs. 37%; P = 0.01) and at Week 12 (62% vs. 38%; P = 0.01) only in high bacterial load patients. Conclusions: Improvement of quality of life with inhaled aztreonam was only evident in patients with high bacterial load. Bacterial load may be a useful biomarker of severity of disease and treatment response.

Pulmonary rehabilitation after exacerbation of bronchiectasis: a pilot randomized controlled trial.

BACKGROUND: Pulmonary rehabilitation improves exercise capacity and reduces risk of future exacerbation in COPD when performed after an exacerbation. There have been no previous studies of post-exacerbation rehabilitation in bronchiectasis. METHODS: Parallel group randomized controlled trial compared pulmonary rehabilitation (PR) to standard care (SC) in patients followed an antibiotic treated exacerbation of bronchiectasis. Patients were randomized following a 14 day course of antibiotics was completed. The primary outcome was 6-min walk distance (6 MW) at 8 weeks. Secondary outcomes were time to the next exacerbation, St.Georges Respiratory Questionnaire, COPD CAT score, Leicester cough questionnaire (LCQ) and FEV1 at 8 and 12 weeks post exacerbation. RESULTS: Forty eight patients were enrolled but only 27 had exacerbations within 12 months of enrolment. Nine patients received pulmonary rehabilitation and 18 received standard care. The 6 MW improved significantly from post-exacerbation to 8 weeks in both groups, with no significant difference between PR and SC- mean difference of 11 m (95% CI -34.3 to 56.3,p = 0.6). Time to the next exacerbation was not significantly different hazard ratio 0.83 (0.31-2.19, p = 0.7). No significant differences were seen between groups in terms of LCQ, CAT, FEV1 or SGRQ between groups. An analysis of probability based on the patients enrolled suggested > 1000 subjects are likely be required to have an > 80% probability of observing a statistically significant difference between PR and SC and any such differences would be likely to be too small to be clinically relevant. CONCLUSIONS: This pilot study identified no significant benefits associated with pulmonary rehabilitation after exacerbations of bronchiectasis. TRIAL REGISTRATION: NCT02179983, registered on Clinicaltrials.gov 29th June 2014.

Sex and BMI Alter the Benefits and Risks of Sulfonylureas and Thiazolidinediones in Type 2 Diabetes: A Framework for Evaluating Stratification Using Routine Clinical and Individual Trial Data.

OBJECTIVE: The choice of therapy for type 2 diabetes after metformin is guided by overall estimates of glycemic response and side effects seen in large cohorts. A stratified approach to therapy would aim to improve on this by identifying subgroups of patients whose glycemic response or risk of side effects differs markedly. We assessed whether simple clinical characteristics could identify patients with differing glycemic response and side effects with sulfonylureas and thiazolidinediones. RESEARCH DESIGN AND METHODS: We studied 22,379 patients starting sulfonylurea or thiazolidinedione therapy in the U.K. Clinical Practice Research Datalink (CPRD) to identify features associated with increased 1-year HbA1c fall with one therapy class and reduced fall with the second. We then assessed whether prespecified patient subgroups defined by the differential clinical factors showed differing 5-year glycemic response and side effects with sulfonylureas and thiazolidinediones using individual randomized trial data from ADOPT (A Diabetes Outcome Progression Trial) (first-line therapy, n = 2,725) and RECORD (Rosiglitazone Evaluated for Cardiovascular Outcomes and Regulation of Glycemia in Diabetes) (second-line therapy, n = 2,222). Further replication was conducted using routine clinical data from GoDARTS (Genetics of Diabetes Audit and Research in Tayside Scotland) (n = 1,977). RESULTS: In CPRD, male sex and lower BMI were associated with greater glycemic response with sulfonylureas and a lesser response with thiazolidinediones (both P < 0.001). In ADOPT and RECORD, nonobese males had a greater overall HbA1c reduction with sulfonylureas than with thiazolidinediones (P < 0.001); in contrast, obese females had a greater HbA1c reduction with thiazolidinediones than with sulfonylureas (P < 0.001). Weight gain and edema risk with thiazolidinediones were greatest in obese females; however, hypoglycemia risk with sulfonylureas was similar across all subgroups. CONCLUSIONS: Patient subgroups defined by sex and BMI have different patterns of benefits and risks on thiazolidinedione and sulfonylurea therapy. Subgroup-specific estimates can inform discussion about the choice of therapy after metformin for an individual patient. Our approach using routine and shared trial data provides a framework for future stratification research in type 2 diabetes.

Pathogenicity and Penetrance of Germline SDHA Variants in Pheochromocytoma and Paraganglioma (PPGL).

Germline SDHA mutations are reported in a minority of pheochromocytoma/paraganglioma (PPGL) cases but are associated with an increased risk of malignancy, leading some to advocate cascade genetic testing and surveillance screening of "at-risk" first-degree relatives. However, such approaches rely on accurate estimates of variant pathogenicity and disease penetrance, which may have been subject to ascertainment and reporting biases, although the recent provision of large population-based DNA sequence data sets may provide a potentially unbiased resource to aid variant interpretation. Thus, the aim of the current study was to evaluate the pathogenicity and penetrance of SDHA variants reported in literature-based PPGL cases by comparing their frequency to those occurring in the Genome Aggregation Database (GnomAD) data set, which provides high-quality DNA sequence data on 138,632 individuals. In total, 39 different missense or loss-of-function (LOF) SDHA variants were identified in 95 PPGL index cases. Notably, many of the PPGL-associated SDHA alleles were observed at an unexpectedly high frequency in the GnomAD cohort, with ~1% and ~0.1% of the background population harboring a rare missense or LOF variant, respectively. Although the pathogenicity of several SDHA alleles was supported by significant enrichment in PPGL cases relative to GnomAD controls, calculations of disease penetrance based on allele frequencies in the respective cohorts resulted in much lower estimates than previously reported, ranging from 0.1% to 4.9%. Thus, although this study provides support for the etiological role of SDHA in PPGL formation, it suggests that most variant carriers will not manifest PPGLs and are unlikely to benefit from periodic surveillance screening.

Pharmacokinetics of metformin in patients with gastrointestinal intolerance.

AIMS: To assess potential causes of metformin intolerance, including altered metformin uptake from the intestine, increased anaerobic glucose utilization and subsequent lactate production, altered serotonin uptake, and altered bile acid pool. METHODS: For this pharmacokinetic study, we recruited 10 severely intolerant and 10 tolerant individuals, matched for age, sex and body mass index. A single 500-mg dose of metformin was administered, with blood sampling at 12 time points over 24 hours. Blood samples were analysed for metformin, lactate, serotonin and bile acid concentrations, and compared across the phenotypes. RESULTS: The intolerant individuals were severely intolerant to 500 mg metformin. No significant difference was identified between tolerant and intolerant cohorts in metformin pharmacokinetics: median (interquartile range [IQR]) peak concentration 2.1 (1.7-2.3) mg/L and 2.0 (1.8-2.2) mg/L, respectively (P = .76); time to peak concentration 2.5 hours; median (IQR) area under the curve (AUC)0-24 16.9 (13.9-18.6) and 13.9 (12.9-16.8) mg/L*h, respectively (P = .72). Lactate concentration peaked at 3.5 hours, with mean peak concentration of 2.4 mmol/L in both cohorts (95% CI 2.0-2.8 and 1.8-3.0 mmol/L, respectively), and similar incremental AUC0-24 in each cohort: tolerant cohort 6.98 (95% CI 3.03-10.93) and intolerant cohort 4.47 (95% CI -3.12-12.06) mmol/L*h (P = .55). Neither serotonin nor bile acid concentrations were significantly different. CONCLUSIONS: Despite evidence of severe intolerance in our cohort, there was no significant difference in metformin pharmacokinetics or systemic measures of lactate, serotonin or bile acids. This suggests that metformin intolerance may be attributable to local factors within the lumen or enterocyte.

Costs and Treatment Pathways for Type 2 Diabetes in the UK: A Mastermind Cohort Study.

INTRODUCTION: Medication therapy for type 2 diabetes has become increasingly complex, and there are few reliable data on the current state of clinical practice. We report treatment pathways and associated costs of medication therapy for people with type 2 diabetes in the UK, their variability and changes over time. METHODS: Prescription and biomarker data for 7159 people with type 2 diabetes were extracted from the GoDARTS cohort study, covering the period 1989-2013. Average follow-up was 10 years. Individuals were prescribed on average 2.4 (SD: 1.2) drugs with average annual costs of £241. We calculated summary statistics for first- and second-line therapies. Linear regression models were used to estimate associations between therapy characteristics and baseline patient characteristics. RESULTS: Average time from diagnosis to first prescription was 3 years (SD: 4.0 years). Almost all first-line therapy (98%) was monotherapy, with average annual cost of £83 (SD: £204) for 3.8 (SD: 3.5) years. Second-line therapy was initiated in 73% of all individuals, at an average annual cost of £219 (SD: £305). Therapies involving insulin were markedly more expensive than other common therapies. Baseline HbA1c was unrelated to future therapy costs, but higher average HbA1c levels over time were associated with higher costs. CONCLUSIONS: Medication therapy has undergone substantial changes during the period covered in this study. For example, therapy is initiated earlier and is less expensive than in the past. The data provided in this study will prove useful for future modelling studies, e.g. of stratified treatment approaches.

Acute kidney injury, plasma lactate concentrations and lactic acidosis in metformin users: A GoDarts study.

AIMS: Metformin is renally excreted and has been associated with the development of lactic acidosis. Although current advice is to omit metformin during illnesses that may increase the risk of acute kidney injury (AKI), the evidence supporting this is lacking. We investigated the relationship between AKI, lactate concentrations and the risk of lactic acidosis in those exposed to metformin. MATERIALS AND METHODS: We undertook a population-based case-control study of lactic acidosis in 1746 participants with Type 2 diabetes and 846 individuals without diabetes with clinically measured lactates with and without AKI between 1994 and 2014. AKI was stratified by severity according to "Kidney Disease: Improving Global Outcomes" guidelines. Mixed-effects logistic and linear regression were used to analyse lactic acidosis risk and lactate concentrations, respectively. RESULTS: Eighty-two cases of lactic acidosis were identified. In Type 2 diabetes, those treated with metformin had a greater incidence of lactic acidosis [45.7 per 100 000 patient years; 95% confidence interval (CI) 35.9-58.3] compared to those not exposed to this drug (11.8 per 100 000 patient years; 95% CI 4.9-28.5). Lactate concentrations were 0.34 mmol/L higher in the metformin-exposed cohort (P < .001). The risk of lactic acidosis was higher in metformin users [odds ratio (OR) 2.3; P = .002] and increased with AKI severity (stage 1: OR 3.0, P = .002; stage 2: OR 9.4, P < .001; stage 3: OR 16.1, P < .001). CONCLUSIONS: A clear association was found between metformin, lactate accumulation and the development of lactic acidosis. This relationship is strongest in those with AKI. These results provide robust evidence to support current recommendations to omit metformin in any illness that may precipitate AKI.

Defining drug response for stratified medicine.

The premise for stratified medicine is that drug efficacy, drug safety, or both, vary between groups of patients, and biomarkers can be used to facilitate more targeted prescribing, with the aim of improving the benefit:risk ratio of treatment. However, many factors can contribute to the variability in response to drug treatment. Inadequate characterisation of the nature and degree of variability can lead to the identification of biomarkers that have limited utility in clinical settings. Here, we discuss the complexities associated with the investigation of variability in drug efficacy and drug safety, and how consideration of these issues a priori, together with standardisation of phenotypes, can increase both the efficiency of stratification procedures and identification of biomarkers with the potential for clinical impact.

Should Studies of Diabetes Treatment Stratification Correct for Baseline HbA1c?

AIMS: Baseline HbA1c is a major predictor of response to glucose lowering therapy and therefore a potential confounder in studies aiming to identify other predictors. However, baseline adjustment may introduce error if the association between baseline HbA1c and response is substantially due to measurement error and regression to the mean. We aimed to determine whether studies of predictors of response should adjust for baseline HbA1c. METHODS: We assessed the relationship between baseline HbA1c and glycaemic response in 257 participants treated with GLP-1R agonists and assessed whether it reflected measurement error and regression to the mean using duplicate 'pre-baseline' HbA1c measurements not included in the response variable. In this cohort and an additional 2659 participants treated with sulfonylureas we assessed the relationship between covariates associated with baseline HbA1c and treatment response with and without baseline adjustment, and with a bias correction using pre-baseline HbA1c to adjust for the effects of error in baseline HbA1c. RESULTS: Baseline HbA1c was a major predictor of response (R2 = 0.19,ß = -0.44,p<0.001).The association between pre-baseline and response was similar suggesting the greater response at higher baseline HbA1cs is not mainly due to measurement error and subsequent regression to the mean. In unadjusted analysis in both cohorts, factors associated with baseline HbA1c were associated with response, however these associations were weak or absent after adjustment for baseline HbA1c. Bias correction did not substantially alter associations. CONCLUSIONS: Adjustment for the baseline HbA1c measurement is a simple and effective way to reduce bias in studies of predictors of response to glucose lowering therapy.

Adherence to Oral Glucose-Lowering Therapies and Associations With 1-Year HbA1c: A Retrospective Cohort Analysis in a Large Primary Care Database.

OBJECTIVE: The impact of taking oral glucose-lowering medicines intermittently, rather than as recommended, is unclear. We conducted a retrospective cohort study using community-acquired U.K. clinical data (Clinical Practice Research Database [CPRD] and GoDARTS database) to examine the prevalence of nonadherence to treatment for type 2 diabetes and investigate its potential impact on HbA1c reduction stratified by type of glucose-lowering medication. RESEARCH DESIGN AND METHODS: Data were extracted for patients treated between 2004 and 2014 who were newly prescribed metformin, sulfonylurea, thiazolidinedione, or dipeptidyl peptidase 4 inhibitors and who continued to obtain prescriptions over 1 year. Cohorts were defined by prescribed medication type, and good adherence was defined as a medication possession ratio ≥0.8. Linear regression was used to determine potential associations between adherence and 1-year baseline-adjusted HbA1c reduction. RESULTS: In CPRD and GoDARTS, 13% and 15% of patients, respectively, were nonadherent. Proportions of nonadherent patients varied by the oral glucose-lowering treatment prescribed (range 8.6% [thiazolidinedione] to 18.8% [metformin]). Nonadherent, compared with adherent, patients had a smaller HbA1c reduction (0.4% [4.4 mmol/mol] and 0.46% [5.0 mmol/mol] for CPRD and GoDARTs, respectively). Difference in HbA1c response for adherent compared with nonadherent patients varied by drug (range 0.38% [4.1 mmol/mol] to 0.75% [8.2 mmol/mol] lower in adherent group). Decreasing levels of adherence were consistently associated with a smaller reduction in HbA1c. CONCLUSIONS: Reduced medication adherence for commonly used glucose-lowering therapies among patients persisting with treatment is associated with smaller HbA1c reductions compared with those taking treatment as recommended. Differences observed in HbA1c responses to glucose-lowering treatments may be explained in part by their intermittent use.