The immune response in tuberculosis.

There are 9 million cases of active tuberculosis reported annually; however, an estimated one-third of the world's population is infected with Mycobacterium tuberculosis and remains asymptomatic. Of these latent individuals, only 5-10% will develop active tuberculosis disease in their lifetime. CD4(+) T cells, as well as the cytokines IL-12, IFN-γ, and TNF, are critical in the control of Mycobacterium tuberculosis infection, but the host factors that determine why some individuals are protected from infection while others go on to develop disease are unclear. Genetic factors of the host and of the pathogen itself may be associated with an increased risk of patients developing active tuberculosis. This review aims to summarize what we know about the immune response in tuberculosis, in human disease, and in a range of experimental models, all of which are essential to advancing our mechanistic knowledge base of the host-pathogen interactions that influence disease outcome.

Author Correction: Progression of whole-blood transcriptional signatures from interferon-induced to neutrophil-associated patterns in severe influenza.

In the version of this article initially published, a source of funding was not included in the Acknowledgements section. That section should include the following: P.J.M.O. was supported by EU FP7 PREPARE project 602525. The error has been corrected in the HTML and PDF version of the article.

Progression of whole-blood transcriptional signatures from interferon-induced to neutrophil-associated patterns in severe influenza.

Transcriptional profiles and host-response biomarkers are used increasingly to investigate the severity, subtype and pathogenesis of disease. We now describe whole-blood mRNA signatures and concentrations of local and systemic immunological mediators in 131 adults hospitalized with influenza, from whom extensive clinical and investigational data were obtained by MOSAIC investigators. Signatures reflective of interferon-related antiviral pathways were common up to day 4 of symptoms in patients who did not require mechanical ventilator support; in those who needed mechanical ventilation, an inflammatory, activated-neutrophil and cell-stress or death ('bacterial') pattern was seen, even early in disease. Identifiable bacterial co-infection was not necessary for this 'bacterial' signature but was able to enhance its development while attenuating the early 'viral' signature. Our findings emphasize the importance of timing and severity in the interpretation of host responses to acute viral infection and identify specific patterns of immune-system activation that might enable the development of novel diagnostic and therapeutic tools for severe influenza.

Structural Predictors of Lung Function Decline in Young Smokers with Normal Spirometry.

Rationale: Chronic obstructive pulmonary disease (COPD) due to tobacco smoking commonly presents when extensive lung damage has occurred. Objectives: We hypothesized that structural change would be detected early in the natural history of COPD and would relate to loss of lung function with time. Methods: We recruited 431 current smokers (median age, 39 yr; 16 pack-years smoked) and recorded symptoms using the COPD Assessment Test (CAT), spirometry, and quantitative thoracic computed tomography (QCT) scans at study entry. These scan results were compared with those from 67 never-smoking control subjects. Three hundred sixty-eight participants were followed every six months with measurement of postbronchodilator spirometry for a median of 32 months. The rate of FEV1 decline, adjusted for current smoking status, age, and sex, was related to the initial QCT appearances and symptoms, measured using the CAT. Measurements and Main Results: There were no material differences in demography or subjective CT appearances between the young smokers and control subjects, but 55.7% of the former had CAT scores greater than 10, and 24.2% reported chronic bronchitis. QCT assessments of disease probability-defined functional small airway disease, ground-glass opacification, bronchovascular prominence, and ratio of small blood vessel volume to total pulmonary vessel volume were increased compared with control subjects and were all associated with a faster FEV1 decline, as was a higher CAT score. Conclusions: Radiological abnormalities on CT are already established in young smokers with normal lung function and are associated with FEV1 loss independently of the impact of symptoms. Structural abnormalities are present early in the natural history of COPD and are markers of disease progression. Clinical trial registered with www.clinicaltrials.gov (NCT03480347).

Influence of age on clinical characteristics, pharmacological management and exacerbations in children with asthma.

BACKGROUND: Asthma trials and guidelines often do not distinguish between adolescents and younger children. Using a large English data set, we evaluated the impact of age on asthma characteristics, management and exacerbations. METHODS: Primary care medical records, 2004-2021, were linked to hospital records. Children were categorised by age at diagnosis and followed until the next age bracket. Ages (based on management guidelines) were 5-8 years, 9-11 years and adolescents (12-16 years). Characteristics evaluated included body mass index, allergies and events before and after diagnosis (symptoms, medication). Exacerbation incidence was calculated. Multivariable Cox proportional hazards determined associations with exacerbations. RESULTS: 119 611 children were eligible: 61 940 (51.8%) 5-8 years, 32 316 (27.7%) 9-11 years and 25 355 (21.2%) adolescents. Several characteristics differed by age; children aged 5-8 years had the highest proportion with eczema, food/drug allergy and cough, but adolescents had the highest proportion with overweight/obesity, aeroallergen sensitisation, dyspnoea and short-acting-beta-agonist only use. Exacerbation rates were highest in the youngest children (per 100 person-years (95% CI): 5-8 years =13.7 (13.4-13.9), 9-11 years =10.0 (9.8-10.4), adolescents =6.7 (6.5-7.0)). Exacerbation risk factors also differed by age; 5-8 years: male, eczema and food/drug allergy were strongly associated, but for children ≥9 years old, obesity and aeroallergen sensitisation were strongly associated. For all children, higher socioeconomic deprivation was significantly associated with having an exacerbation. Delayed diagnosis was most common in children aged 5-8 years and was associated with increased exacerbations across all ages. CONCLUSION: Children's baseline characteristics and exacerbation rates varied according to their age group. Clinical guidelines should consider age at time of diagnosis more discretely than the broad range, 5-16 years, as this appears to impact on asthma severity and management.

SABINA + Hong Kong: a territory wide study of prescribing trends and outcomes associated with the use of short-acting ß2 agonists in the Chinese population.

BACKGROUND: Excessive use of short-acting ß2 agonists (SABA) in patients with asthma continues to be a notable concern due to its link to higher mortality rates. Global relevance of SABA overuse in asthma management cannot be understated, it poses significant health risk to patients with asthma and imposes burden on healthcare systems. This study, as part of global SABINA progamme, aimed to describe the prescribing patterns and clinical outcomes associated with SABA use in the Chinese population. METHODS: Retrospective cohort study was conducted using anonymized electronic healthcare records of Clinical Data Analysis and Reporting System (CDARS) from Hong Kong Hospital Authority (HA). Patients newly diagnosed with asthma between 2011 and 2018 and aged ≥12 years were included, stratified by SABA use (≤2, 3-6, 7-10, or ≥11 canisters/year) during one-year baseline period since asthma diagnosis date. Patients were followed up from one-year post-index until earliest censoring of events: outcome occurrence and end of study period (31 December 2020). Cox proportional regression and negative binomial regression were used to estimate the mortality risk and frequency of hospital admissions associated with SABA use respectively, after adjusting for age, sex, Charlson Comorbidity Index (CCI), and inhaled corticosteroid (ICS) dose. Outcomes include all-cause, asthma-related, and respiratory-related mortality, frequency of hospital admissions for any cause, and frequency of hospital admissions due to asthma. RESULTS: 17,782 patients with asthma (mean age 46.7 years, 40.8% male) were included and 59.1% of patients were overusing SABA (≥ 3 canisters per year). Each patient was prescribed a median of 5.61 SABA canisters/year. SABA overuse during baseline period was associated with higher all-cause mortality risk compared to patients with ≤2 canisters/year. Association was dose-dependent, highest risk in those used ≥11 canisters/year (adjusted hazard ratio: 1.42, 95% CI: 1.13, 1.79) and 3-6 canisters/year (adjusted hazard ratio: 1.22, 95% CI: 1.00, 1.50). Higher SABA prescription volume associated with increased frequency of hospital admissions with greatest risk observed in 7-10 canisters/year subgroup (adjusted rate ratio: 4.81, 95% CI: 3.66, 6.37). CONCLUSIONS: SABA overuse is prevalent and is associated with increased all-cause mortality risk and frequency of hospital admissions among the patients with asthma in Hong Kong.

Asthma and incident coronary heart disease: an observational and Mendelian randomisation study.

BACKGROUND: Observational studies suggest asthma is a risk factor for coronary heart disease (CHD) and sex modifies the risk, but they may suffer from methodological limitations. To overcome these, we applied a "triangulation approach", where different methodologies, with different potential biases, were leveraged to enhance confidence in findings. METHODS: First, we conducted an observational study using UK medical records to match asthma patients 1:1, by age, sex and general practitioner (GP) practice, to the general population. We measured the association between asthma and incident CHD (myocardial infarction: hospitalisation/death) by applying minimal sufficient adjustment: model 1, smoking, body mass index, oral corticosteroids, atopy and deprivation; model 2, additionally adjusting for healthcare behaviour (GP consultation frequency). Second, we conducted a Mendelian randomisation (MR) study using data from the UK Biobank, Trans-National Asthma Genetic Consortium (TAGC) and Coronary Artery Disease Genome-wide Replication and Meta-analysis consortium (CARDIoGRAM). Using 64 asthma single nucleotide polymorphisms, the effect of asthma on CHD was estimated with inverse variance-weighted meta-analysis and methods that adjust for pleiotropy. RESULTS: In our observational study (n=1 522 910), we found asthma was associated with 6% increased risk of CHD (model 1: HR 1.06, 95% CI 1.01-1.13); after accounting for healthcare behaviour, we found no association (model 2: HR 0.99, 95% CI 0.94-1.05). Asthma severity did not modify the association, but sex did (females: HR 1.11, 95% CI 1.01-1.21; males: HR 0.91, 95% CI 0.84-0.98). Our MR study (n=589 875) found no association between asthma and CHD (OR 1.01, 95% CI 0.98-1.04) and no modification by sex. CONCLUSIONS: Our findings suggest that asthma is not a risk factor for CHD. Previous studies may have suffered from detection bias or residual confounding.

Covid-19 pandemic and asthma: What did we learn?

This review addresses some of the major lessons we have learnt regarding asthma and the covid-19 pandemic, including susceptibility to SARS-CoV-2 infection and severe covid-19, potentially protective factors, comparison to other respiratory infections, changes in healthcare behaviour from the perspective of patients and clinicians, medications to treat or prevent covid-19, and post-covid syndrome.

Asthma Phenotypes and COVID-19 Risk: A Population-based Observational Study.

Rationale: Studies have suggested some patients with asthma are at risk of severe coronavirus disease (COVID-19), but they have had limited data on asthma phenotype and have not considered if risks are specific to COVID-19. Objectives: To determine the effect of asthma phenotype on three levels of COVID-19 outcomes. Compare hospitalization rates with influenza and pneumonia. Methods: Electronic medical records were used to identify patients with asthma and match them to the general population. Patient-level data were linked to Public Health England severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test data, hospital, and mortality data. Asthma was phenotyped by medication, exacerbation history, and type 2 inflammation. The risk of each outcome, adjusted for major risk factors, was measured using Cox regression. Measurements and Main Results: A total of 434,348 patients with asthma and 748,327 matched patients were included. All patients with asthma had a significantly increased risk of a General Practice diagnosis of COVID-19. Asthma with regular inhaled corticosteroid (ICS) use (hazard ratio [HR], 1.27; 95% confidence interval [CI], 1.01-1.61), intermittent ICS plus add-on asthma medication use (HR, 2.00; 95% CI, 1.43-2.79), regular ICS plus add-on use (HR, 1.63; 95% CI, 1.37-1.94), or with frequent exacerbations (HR, 1.82; 95% CI, 1.34-2.47) was significantly associated with hospitalization. These phenotypes were significantly associated with influenza and pneumonia hospitalizations. Only patients with regular ICS plus add-on asthma therapy (HR, 1.70; 95% CI, 1.27-2.26) or frequent exacerbations (HR, 1.66; 95% CI, 1.03-2.68) had a significantly higher risk of ICU admission or death. Atopy and blood eosinophil count were not associated with severe COVID-19 outcomes. Conclusions: More severe asthma was associated with more severe COVID-19 outcomes, but type 2 inflammation was not. The risk of COVID-19 hospitalization appeared to be similar to the risk with influenza or pneumonia.

Burden of preschool wheeze and progression to asthma in the UK: Population-based cohort 2007 to 2017.

BACKGROUND: Wheeze is one of the most common symptoms of preschool children (age 1-5 years), yet we have little understanding of the burden in the United Kingdom. OBJECTIVES: We sought to determine prevalence and pattern of physician-confirmed preschool wheeze, related health care utilization, and factors associated with progression to school-age asthma. METHODS: We used nationally representative primary and secondary care electronic medical records between 2007 and 2017 to identify preschool children with wheeze. Factors associated with asthma progression were identified in a nested cohort of children with follow-up from age 1 to 2 years, until at least age 8 years. RESULTS: From 1,021,624 preschool children, 69,261 were identified with wheeze. Prevalence of preschool wheeze was 7.7% in 2017. Wheeze events were lowest in August and highest in late-autumn/early-winter. During median follow-up of 2 years (interquartile range, 1.2-4.0 years), 15.8% attended an emergency department, and 13.9% had a hospital admission, for a respiratory disorder. The nested cohort with prolonged follow-up identified 15,085 children; 35.5% progressed to asthma between age 5 and 8 years. Of children with preschool wheeze, without an asthma diagnosis, 34.9% were prescribed inhaled corticosteroids and 15.6% oral corticosteroids. The factors most strongly associated with progression to asthma were wheeze frequency and severity, atopy, prematurity, maternal asthma severity, and first reported wheeze event occurring in September. CONCLUSIONS: Preschool wheeze causes considerable health care burden, and a large number of children are prescribed asthma medication and have unplanned secondary care visits. Multiple factors influence progression to asthma, including first wheeze event occurring in September.

Health and cost impact of stepping down asthma medication for UK patients, 2001-2017: A population-based observational study.

BACKGROUND: Guidelines recommend stepping down asthma treatment to the minimum effective dose to achieve symptom control, prevent adverse side effects, and reduce costs. Limited data exist on asthma prescription patterns in a real-world setting. We aimed to evaluate the appropriateness of doses prescribed to a UK general asthma population and assess whether stepping down medication increased exacerbations or reliever use, as well as its impact on costs. METHODS AND FINDINGS: We used nationwide UK primary care medical records, 2001-2017, to identify 508,459 adult asthma patients managed with preventer medication. Prescriptions of higher-level medication: medium/high-dose inhaled corticosteroids (ICSs) or ICSs + add-on medication (long-acting ß2-agonist [LABA], leukotriene receptor antagonist [LTRA], theophylline, or long-acting muscarinic antagonist [LAMA]) steadily increased over time (2001 = 49.8%, 2017 = 68.3%). Of those prescribed their first preventer, one-third were prescribed a higher-level medication, of whom half had no reliever prescription or exacerbation in the year prior. Of patients first prescribed ICSs + 1 add-on, 70.4% remained on the same medication during a mean follow-up of 6.6 years. Of those prescribed medium/high-dose ICSs as their first preventer, 13.0% already had documented diabetes, cataracts, glaucoma, or osteopenia/osteoporosis. A cohort of 125,341 patients were drawn to assess the impact of stepping down medication: mean age 50.4 years, 39.4% males, 39,881 stepped down. Exposed patients were stepped down by dropping their LABAs or another add-on or by halving their ICS dose (halving their mean-daily dose or their inhaler dose). The primary and secondary outcomes were, respectively, exacerbations and an increase in reliever prescriptions. Multivariable regression was used to assess outcomes and determine the prognostic factors for initiating stepdown. There was no increased exacerbation risk for each possible medication stepdown (adjusted hazard ratio, 95% CI, p-value: ICS inhaler dose = 0.86, 0.77-0.93, p < 0.001; ICS mean daily = 0.80, 0.74-0.87, p < 0.001; LABA = 1.01, 0.92-1.11, p = 0.87, other add-on = 1.00, 0.91-1.09, p = 0.79) and no increase in reliever prescriptions (adjusted odds ratio, 95% CI, p-value: ICS inhaler dose = 0.99, 0.98-1.00, p = 0.59; ICS mean daily = 0.78, 0.76-0.79, p < 0.001; LABA = 0.83, 0.82-0.85, p < 0.001; other add-on = 0.86, 0.85-0.87, p < 0.001). Prognostic factors to initiate stepdown included medication burden, but not medication side effects. National Health Service (NHS) indicative prices were used for cost estimates. Stepping down medication, either LABAs or ICSs, could save annually around £17,000,000 or £8,600,000, respectively. Study limitations include the possibility that prescribed medication may not have been dispensed or adhered to and the reason for stepdown was not documented. CONCLUSION: In this UK study, we observed that asthma patients were increasingly prescribed higher levels of treatment, often without clear clinical indication for such high doses. Stepping down medication did not adversely affect outcomes and was associated with substantial cost savings.

Hospitalisation and mortality in patients with comorbid COPD and heart failure: a systematic review and meta-analysis.

BACKGROUND: Discrepancy exists amongst studies investigating the effect of comorbid heart failure (HF) on the morbidity and mortality of chronic obstructive pulmonary disease (COPD) patients. METHODS: MEDLINE and Embase were searched using a pre-specified search strategy for studies comparing hospitalisation, rehospitalisation, and mortality of COPD patients with and without HF. Studies must have reported crude and/or adjusted rate ratios, risk ratios, odds ratios (OR), or hazard ratios (HR). RESULTS: Twenty-eight publications, reporting 55 effect estimates, were identified that compared COPD patients with HF with those without HF. One study reported on all-cause hospitalisation (1 rate ratio). Two studies reported on COPD-related hospitalisation (1 rate ratio, 2 OR). One study reported on COPD- or cardiovascular-related hospitalisation (4 HR). One study reported on 90-day all-cause rehospitalisation (1 risk ratio). One study reported on 3-year all-cause rehospitalisation (2 HR). Four studies reported on 30-day COPD-related rehospitalisation (1 risk ratio; 5 OR). Two studies reported on 1-year COPD-related rehospitalisation (1 risk ratio; 1 HR). One study reported on 3-year COPD-related rehospitalisation (2 HR). Eighteen studies reported on all-cause mortality (1 risk ratio; 4 OR; 24 HR). Five studies reported on all-cause inpatient mortality (1 risk ratio; 4 OR). Meta-analyses of hospitalisation and rehospitalisation were not possible due to insufficient data for all individual effect measures. Meta-analysis of studies requiring spirometry for the diagnosis of COPD found that risk of all-cause mortality was 1.61 (pooled HR; 95%CI: 1.38, 1.83) higher in patients with HF than in those without HF. CONCLUSIONS: In this systematic review, we investigated the effect of HF comorbidity on hospitalisation and mortality of COPD patients. There is substantial evidence that HF comorbidity increases COPD-related rehospitalisation and all-cause mortality of COPD patients. The effect of HF comorbidity may differ depending on COPD phenotype, HF type, or HF severity and should be the topic of future research.

Exacerbation Patterns in Adults with Asthma in England. A Population-based Study.

RATIONALE: Asthma is heterogeneous and knowledge on exacerbation patterns is lacking. Previous studies have had a relatively short follow-up or focused on severe disease. OBJECTIVES: To describe exacerbation patterns over a prolonged follow-up in a population that includes patients of all disease severity. METHODS: We used electronic health care records to identify patients with asthma aged 18-55 years and their exacerbations from 2007 to 2015. A cohort with greater than or equal to 7 years of data was used to describe exacerbation patterns by asthma severity defined by medication use. Effect estimates for risk factors were calculated for sporadic (single year of exacerbations) and recurrent (>1 yr) exacerbation patterns, using logistic regression. In a nested case-control design, the association between a history of exacerbations, spanning 5 years, and a future exacerbation was examined. MEASUREMENTS AND MAIN RESULTS: A total of 51,462 patients were eligible for the 7-year cohort; 64% had no exacerbations. Of those who exacerbated, 51% did so only once; exacerbation frequency increased with disease severity. Only 370 patients (0.7%) were characterized by a frequent-exacerbator phenotype (yearly exacerbations), of whom 58% had mild/moderate asthma. Exacerbation risk factors were not uniquely associated with a particular exacerbation pattern. A past exacerbation increased the risk of a future exacerbation more than all other factors, although this effect dissipated over 5 years. CONCLUSIONS: During 7 years of follow-up, exacerbations occur in around one-third of patients. Of those who exacerbate, half do not do so again; the timing of future exacerbations is largely unpredictable. Just 2% exhibit a frequent-exacerbator phenotype. Past exacerbation patterns are the most informative risk factor for predicting future exacerbations.

Cost saving of switching to equivalent inhalers and its effect on health outcomes.

BACKGROUND: Switching inhalers to cheaper equivalent products is often advocated as a necessary cost saving measure, yet the impact on patient's health and healthcare utilisation has not been measured. METHODS: We identified asthma and chronic obstructive pulmonary disease (COPD) patients from UK primary care electronic healthcare records between 2000 and 2016. A self-controlled case series was used to estimate incidence rate ratios (IRR); comparing outcome rates during the risk period, 3 months after the exposure (financially motivated switch), and control periods (preswitch and postrisk period). Four outcomes were assessed: disease exacerbation, general practitioner consultation, non-specific respiratory events and adverse-medication events. Medication possession ratio (MPR) was calculated to assess adherence. 2017 National Health Service indicative prices were used to estimate cost differences per equivalent dose. RESULTS: We identified a cohort of 569 901 asthma and 171 231 COPD regular inhaler users, 2% and 6% had been switched, respectively. Inhaler switches between a brand-to-generic inhaler, and all other switches (brand-to-brand, generic-to-generic, generic-to-brand), were associated with reduced exacerbations (brand-to-generic: IRR=0.75, 95% CI 0.64 to 0.88; all other: IRR=0.79, 95% CI 0.71 to 0.88). Gender, age, therapeutic class, inhaler device and inhaler-technique checks did not significantly modify this association (p<0.05). The rate of consultations, respiratory-events and adverse-medication events did not change significantly (consultations: IRR=1.00, 95% CI 0.99 to 1.01; respiratory-events: IRR=0.96, 95% CI 0.95 to 0.97; adverse-medication-events: IRR=1.05, 95% CI 0.96 to 1.15). Adherence significantly increased post-switch (median MPR: pre-switch=54%, post-switch=62%; p<0.001). Switching patients, in the cohort of regular inhaler users, to the cheapest equivalent inhaler, could have saved around £6 million annually. CONCLUSION: Switching to an equivalent inhaler in patients with asthma or COPD appeared safe and did not negatively affect patient's health or healthcare utilisation.

Changing causes of death for patients with chronic respiratory disease in England, 2005-2015.

BACKGROUND: Chronic respiratory diseases (CRD) are common, are increasing in prevalence, and cause significant morbidity and mortality worldwide. However, we have limited knowledge on causes of death of patients with CRD in the general population. OBJECTIVE: We evaluated mortality rates and causes of death over time in patients with CRD. METHODS: We used linked primary care and mortality data to determine mortality rates and the most common causes of death in people with CRD (including asthma, bronchiectasis, COPD and interstitial lung diseases (ILD)) during 2005-2015 in England. RESULTS: We identified 558 888 patients with CRD (451 830 asthma, 137 709 COPD, 19 374 bronchiectasis, 10 745 ILD). The age-standardised mortality rate of patients with CRD was 1607 per 100 000 persons (asthma=856, COPD=1503, ILD=2609, bronchiectasis=1463). CRD mortality was overall 54% higher than the general population. A third of patients with CRD died from respiratory-related causes. Respiratory-related mortality was constant, while cardiovascular-related mortality decreased significantly over time. COPD accounted for the majority of respiratory-related deaths (66% overall) in all patient groups except ILD. CONCLUSIONS: Patients with CRD continue to experience substantial morbidity and mortality due to respiratory diseases. Disease-modifying intervention strategies are needed to improve outcomes for patients with CRD.

Changing prevalence of current asthma and inhaled corticosteroid treatment in the UK: population-based cohort 2006-2016.

Asthma is the most common respiratory disorder in the UK, yet we have incomplete knowledge on the prevalence of current disease, treatment and exacerbations.We used UK electronic healthcare records, 2006-2016, to estimate the prevalence of current asthma by year, sex and age (<5, 5-11, 12-17, 18-24, 25-54 and ≥55 years), and the proportion prescribed inhaled corticosteroids (ICS) and additional asthma therapy, treated for exacerbations and other asthma care markers.Overall current asthma prevalence was 6.5% in 2016 (7.2% in 2006). Prevalence fell in those aged <45 years. The lowest prevalence and largest absolute decrease was in children aged <5 years. In 2016, 80% of current asthma patients were managed on ICS (65% in 2006); this increase occurred in all age groups, primarily due to an increase in low-dose ICS. During this time there was an increase in all age groups in the proportion prescribed additional asthma therapy, treated for an exacerbation within primary care and given an annual asthma review or management plan. Hospitalised exacerbations showed minimal change over time.Asthma remains highly prevalent and a significant healthcare burden. In those with a diagnosis, there was an increase in ICS prescriptions and treatment of exacerbations across all age groups. This may reflect a trend towards more aggressive asthma management within primary care. An apparent decline in prevalence was observed in those aged <45 years, particularly in children aged <5 years.

Risk factors and secondary care utilisation in a primary care population with non-tuberculous mycobacterial disease in the UK.

Prior research has identified risk factors associated with developing non-tuberculous mycobacterial disease (NTMD); we identified risk factors and secondary care utilisation of NTMD patients in the UK. This was a matched case-control study using electronic healthcare records from Clinical Practice Research Datalink from 2006 to 2016. NTMD was defined using prescription data and Read codes, based on international guidelines. Risk factors for NTMD were investigated using conditional logistic regression within a representative general population. All-cause secondary care utilisation (combined inpatient, outpatient, emergency visits) was investigated for participants with linked Hospital Episode Statistics (HES), using incidence rate ratio (IRR) from 2007 to 2015. We identified 1225 individuals with NTMD. A subset of individuals (426 patients) were eligible for linkage with HES. In the adjusted model, risk factors most strongly associated with an increased likelihood of NTMD included previous tuberculosis (OR 69.0; 47.7-99.8); bronchiectasis (OR 23.3; 12.4-43.9); lung cancer (OR 14.9; 3.98-55.7); oral corticosteroids (OCS; OR 7.28; 4.94-10.7); immunosuppressive (excluding corticosteroids) medication (OR 3.05; 1.15-8.10); being underweight (odds ratio (OR) 2.92; 95% CI 1.95, 4.36); and rheumatoid arthritis (OR 2.12; 1.05-4.27). NTMD patients had significantly higher rates of all-cause secondary care utilisation than non-NTMD patients (IRR 5.80; 5.14-6.46). Using a representative adult population, we identified prior TB, bronchiectasis, lung cancer, immunosuppressive medication, and OCS as the risk factors associated with the highest odds of developing NTMD in the UK. Patients with NTMD experienced nearly six times more all-cause secondary care events following their NTMD diagnosis than patients without NTMD.

Exacerbation risk and characterisation of the UK's asthma population from infants to old age.

BACKGROUND: Few studies have examined the characteristics of a general asthma population; most have focused on more severe patients or severe exacerbations. METHODS: This population-based cohort study, from April 2007 to September 2015, used linked primary and secondary care electronic healthcare records (Clinical Practice Research Datalink, Hospital Episode Statistics). Characteristics of four age cohorts, 'Under 5s', '5 to 17s', '18 to 54s', '55+', were described. Exacerbation risk factors, including asthma severity (measured by the British Thoracic Society (BTS) stepwise approach), were assessed using Poisson regression. RESULTS: 424 326 patients with current asthma were eligible (n, median follow-up: 'Under 5s'=17 320, 1 year; '5 to 17s'=82 707, 3.3 years; '18 to 54s'=210 724, 4 years; '55+'=113 575, 5.1 years). Over 60% of the total study population had mild asthma (BTS steps 1/2). There were differences between the cohort's characteristics, including by gender, disease severity and exacerbation pattern. The rate of exacerbations was highest in the oldest cohort and lowest in the '5 to 17s' cohort (rate per 10 person-years (95% CI), 'Under 5s'=4.27 (4.18 to 4.38), '5 to 17s'=1.48 (1.47 to 1.50), '18 to 54s'=3.22 (3.21 to 3.24), '55+'=9.40 (9.37 to 9.42)). In all cohorts, exacerbation rates increased with increasing asthma severity, after adjusting for confounders including gender, socioeconomic status, smoking, body mass index, atopy, rhinitis, gastro-oesophageal reflux, anxiety, depression and COPD. CONCLUSION: The majority of UK patients with asthma had mild asthma and did not experience an exacerbation during follow-up. Patients aged ≥55 years had the lowest proportion with mild asthma and highest rate of exacerbations; the opposite was found in patients aged between 5 and 18 years.