Face Mask Sampling for the Detection of Mycobacterium tuberculosis in Expelled Aerosols

Background

Although tuberculosis is transmitted by the airborne route, direct information on the natural output of bacilli into air by source cases is very limited. We sought to address this through sampling of expelled aerosols in face masks that were subsequently analyzed for mycobacterial contamination.

Methods

In series 1, 17 smear microscopy positive patients wore standard surgical face masks once or twice for periods between 10 minutes and 5 hours; mycobacterial contamination was detected using a bacteriophage assay. In series 2, 19 patients with suspected tuberculosis were studied in Leicester UK and 10 patients with at least one positive smear were studied in The Gambia. These subjects wore one FFP30 mask modified to contain a gelatin filter for one hour; this was subsequently analyzed by the Xpert MTB/RIF system.

Results

In series 1, the bacteriophage assay detected live mycobacteria in 11/17 patients with wearing times between 10 and 120 minutes. Variation was seen in mask positivity and the level of contamination detected in multiple samples from the same patient. Two patients had non-tuberculous mycobacterial infections. In series 2, 13/20 patients with pulmonary tuberculosis produced positive masks and 0/9 patients with extrapulmonary or non-tuberculous diagnoses were mask positive. Overall, 65% of patients with confirmed pulmonary mycobacterial infection gave positive masks and this included 3/6 patients who received diagnostic bronchoalveolar lavages.

Conclusion

Mask sampling provides a simple means of assessing mycobacterial output in non-sputum expectorant. The approach shows potential for application to the study of airborne transmission and to diagnosis.     

Association between Exposure to Environmental Tobacco Smoke and Biomarkers of Oxidative Stress Among Patients Hospitalised with Acute Myocardial Infarction

Objective

To determine whether exposure to environmental tobacco smoke was associated with oxidative stress among patients hospitalised for acute myocardial infarction.

Design

An existing cohort study of 1,261 patients hospitalised for acute myocardial infarction.

Setting

Nine acute hospitals in Scotland.

Participants

Sixty never smokers who had been exposed to environmental tobacco smoke (admission serum cotinine ≥3.0 ng/mL) were compared with 60 never smokers who had not (admission serum cotinine ≤0.1 ng/mL).

Intervention

None.

Main outcome measures

Three biomarkers of oxidative stress (protein carbonyl, malondialdehyde (MDA) and oxidised low-density lipoprotein (ox-LDL)) were measured on admission blood samples and adjusted for potential confounders.

Results

After adjusting for baseline differences in age, sex and socioeconomic status, exposure to environmental tobacco smoke was associated with serum concentrations of both protein carbonyl (beta coefficient 7.96, 95% CI 0.76, 15.17, p = 0.031) and MDA (beta coefficient 10.57, 95% CI 4.32, 16.81, p = 0.001) but not ox-LDL (beta coefficient 2.14, 95% CI −8.94, 13.21, p = 0.703).

Conclusions

Exposure to environmental tobacco smoke was associated with increased oxidative stress. Further studies are requires to explore the role of oxidative stress in the association between environmental tobacco smoke and myocardial infarction.     

Common household chemicals and the allergy risks in pre-school age children

Background

The risk of indoor exposure to volatile organic compounds (VOCs) on allergic airway diseases in children remains unknown.

Objective

We examined the residential concentrations of VOCs, emitted from building materials, paints, furniture, and other lifestyle practices and the risks of multiple allergic diseases as well as the IgE-sensitization in pre-school age children in Sweden.

Methods

In a case-control investigation (198 case children with asthma and allergy and 202 healthy controls), air samples were collected in the room where the child slept. The air samples were analyzed for the levels of eight classes of VOCs.

Results

A natural-log unit of summed propylene glycol and glycol ethers (PGEs) in bedroom air (equal to interquartile range, or 3.43 – 15.65 µg/m³) was associated with 1.5-fold greater likelihood of being a case (95% CI, 1.1 – 2.1), 1.5-fold greater likelihood of asthma (95% CI, 1.0 – 2.3), 2.8-fold greater likelihood of rhinitis (95% CI, 1.6 – 4.7), and 1.6-fold greater likelihood of eczema (95% CI, 1.1 – 2.3), accounting for gender, secondhand smoke, allergies in both parents, wet cleaning with chemical agents, construction period of the building, limonene, cat and dog allergens, butyl benzyl phthalate (BBzP), and di(2-ethylhexyl)phthalate (DEHP). When the analysis was restricted to the cases, the same unit concentration was associated with 1.8-fold greater likelihood of IgE-sensitization (95% CI, 1.1 – 2.8) compared to the non-IgE sensitized cases. No similar associations were found for the other classes of VOCs.

Conclusion

We propose a novel hypothesis that PGEs in indoor air exacerbate and/or induce the multiple allergic symptoms, asthma, rhinitis and eczema, as well as IgE sensitization respectively.     

Traffic-related air pollution and respiratory symptoms among asthmatic children,resident in Mexico City: the EVA cohort study

Background

Taffic-related air pollution has been related to adverse respiratory outcomes; however, there is still uncertainty concerning the type of vehicle emission causing most deleterious effects.

Methods

A panel study was conducted among 147 asthmatic and 50 healthy children, who were followed up for an average of 22 weeks. Incidence density of coughing, wheezing and breathing difficulty was assessed by referring to daily records of symptoms and child''s medication. The association between exposure to pollutants and occurrence of symptoms was evaluated using mixed-effect models with binary response and poisson regression.

Results

Wheezing was found to relate significantly to air pollutants: an increase of 17.4 μg/m³ (IQR) of PM_2.5 (24-h average) was associated with an 8.8% increase (95% CI: 2.4% to 15.5%); an increase of 34 ppb (IQR) of NO₂ (1-h maximum) was associated with an 9.1% increase (95% CI: 2.3% to16.4%) and an increase of 48 ppb (IQR) in O₃ levels (1 hr maximum) to an increase of 10% (95% CI: 3.2% to 17.3%). Diesel-fueled motor vehicles were significantly associated with wheezing and bronchodilator use (IRR = 1.29; 95% CI: 1.03 to 1.62, and IRR = 1.32; 95% CI: 0.99 to 1.77, respectively, for an increase of 130 vehicles hourly, above the 24-hour average).

Conclusion

Respiratory symptoms in asthmatic children were significantly associated with exposure to traffic exhaust, especially from natural gas and diesel-fueled vehicles.     

Alterations in Skeletal Muscle Cell Homeostasis in a Mouse Model of Cigarette Smoke Exposure

Background

Skeletal muscle dysfunction is common in chronic obstructive pulmonary disease (COPD), a disease mainly caused by chronic cigarette use. An important proportion of patients with COPD have decreased muscle mass, suggesting that chronic cigarette smoke exposure may interfere with skeletal muscle cellular equilibrium. Therefore, the main objective of this study was to investigate the kinetic of the effects that cigarette smoke exposure has on skeletal muscle cell signaling involved in protein homeostasis and to assess the reversibility of these effects.

Methods

A mouse model of cigarette smoke exposure was used to assess skeletal muscle changes. BALB/c mice were exposed to cigarette smoke or room air for 8 weeks, 24 weeks or 24 weeks followed by 60 days of cessation. The gastrocnemius and soleus muscles were collected and the activation state of key mediators involved in protein synthesis and degradation was assessed.

Results

Gastrocnemius and soleus were smaller in mice exposed to cigarette smoke for 8 and 24 weeks compared to room air exposed animals. Pro-degradation proteins were induced at the mRNA level after 8 and 24 weeks. Twenty-four weeks of cigarette smoke exposure induced pro-degradation proteins and reduced Akt phosphorylation and glycogen synthase kinase-3β quantity. A 60-day smoking cessation period reversed the cell signaling alterations induced by cigarette smoke exposure.

Conclusions

Repeated cigarette smoke exposure induces reversible muscle signaling alterations that are dependent on the duration of the cigarette smoke exposure. These results highlights a beneficial aspect associated with smoking cessation.     

Validation of an Automated Cough Detection Algorithm for Tracking Recovery of Pulmonary Tuberculosis Patients

Background

A laboratory-free test for assessing recovery from pulmonary tuberculosis (TB) would be extremely beneficial in regions of the world where laboratory facilities are lacking. Our hypothesis is that analysis of cough sound recordings may provide such a test. In the current paper, we present validation of a cough analysis tool.

Methodology/Principal Findings

Cough data was collected from a cohort of TB patients in Lima, Peru and 25.5 hours of recordings were manually annotated by clinical staff. Analysis software was developed and validated by comparison to manual scoring. Because many patients cough in bursts, coughing was characterized in terms of cough epochs. Our software correctly detects 75.5% of cough episodes with a specificity of 99.6% (comparable to past results using the same definition) and a median false positive rate of 4 false positives/hour, due to the noisy, real-world nature of our dataset. We then manually review detected coughs to eliminate false positives, in effect using the algorithm as a pre-screening tool that reduces reviewing time to roughly 5% of the recording length. This cough analysis approach provides a foundation to support larger-scale studies of coughing rates over time for TB patients undergoing treatment.     

High Humidity Leads to Loss of Infectious Influenza Virus from Simulated Coughs

Background

The role of relative humidity in the aerosol transmission of influenza was examined in a simulated examination room containing coughing and breathing manikins.

Methods

Nebulized influenza was coughed into the examination room and Bioaerosol samplers collected size-fractionated aerosols (<1 µM, 1–4 µM, and >4 µM aerodynamic diameters) adjacent to the breathing manikin’s mouth and also at other locations within the room. At constant temperature, the RH was varied from 7–73% and infectivity was assessed by the viral plaque assay.

Results

Total virus collected for 60 minutes retained 70.6–77.3% infectivity at relative humidity ≤23% but only 14.6–22.2% at relative humidity ≥43%. Analysis of the individual aerosol fractions showed a similar loss in infectivity among the fractions. Time interval analysis showed that most of the loss in infectivity within each aerosol fraction occurred 0–15 minutes after coughing. Thereafter, losses in infectivity continued up to 5 hours after coughing, however, the rate of decline at 45% relative humidity was not statistically different than that at 20% regardless of the aerosol fraction analyzed.

Conclusion

At low relative humidity, influenza retains maximal infectivity and inactivation of the virus at higher relative humidity occurs rapidly after coughing. Although virus carried on aerosol particles <4 µM have the potential for remaining suspended in air currents longer and traveling further distances than those on larger particles, their rapid inactivation at high humidity tempers this concern. Maintaining indoor relative humidity >40% will significantly reduce the infectivity of aerosolized virus.     

Professional and home-made face masks reduce exposure to respiratory infections among the general population

Background

Governments are preparing for a potential influenza pandemic. Therefore they need data to assess the possible impact of interventions. Face-masks worn by the general population could be an accessible and affordable intervention, if effective when worn under routine circumstances.

Methodology

We assessed transmission reduction potential provided by personal respirators, surgical masks and home-made masks when worn during a variety of activities by healthy volunteers and a simulated patient.

Principal Findings

All types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear or type of activity, but with a high degree of individual variation. Personal respirators were more efficient than surgical masks, which were more efficient than home-made masks. Regardless of mask type, children were less well protected. Outward protection (mask wearing by a mechanical head) was less effective than inward protection (mask wearing by healthy volunteers).

Conclusions/Significance

Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks worn by patients may not offer as great a degree of protection against aerosol transmission.     

Pertussis Prevalence and Its Determinants among Children with Persistent Cough in Urban Uganda

Background

We determined prevalence of pertussis infection and its associated host and environmental factors to generate information that would guide strategies for disease control.

Methods

In a cross-sectional study, 449 children aged 3 months to 12 years with persistent cough lasting ≥14 days were enrolled and evaluated for pertussis using DNA polymerase chain reaction (PCR) and ELISA serology tests.

Results

Pertussis prevalence was 67 (15% (95% Confidence Interval (CI): 12–18)) and 81 (20% (95% CI: 16–24)) by PCR and ELISA, respectively among 449 participating children. The prevalence was highest in children with >59 months of age despite high vaccination coverage of 94% in this age group. Study demographic and clinical characteristics were similar between pertussis and non-pertussis cases. Of the 449 children, 133 (30%) had a coughing household member and 316 (70%) did not. Among 133 children that had a coughing household member, sex of child, sharing bed with a coughing household member and having a coughing individual in the neighborhood were factors associated with pertussis. Children that had shared a bed with a coughing household individual had seven-fold likelihood of having pertussis compared to children that did not (odds ratio (OR) 7.16 (95% CI: 1.24–41.44)). Among the 316 children that did not have a coughing household member, age <23 months, having or contact with a coughing individual in neighborhood, a residence with one room, and having a caretaker with >40 years of age were the factors associated with pertussis. Age <23months was three times more likely to be associated with pertussis compared to age 24–59 months (OR 2.97 (95% CI: 1.07–8.28)).

Conclusion

Findings suggest high prevalence of pertussis among children with persistent cough at a health facility and it was marked in children >59 months of age, suggesting the possibility of waning immunity. The factors associated with pertussis varied by presence or absence of a coughing household member.     

Two-Minute Training for Improving Neonatal Bag and Mask Ventilation

Objectives

To test effectivity of a two-minute training consisting of a few key-points in ventilation using the self-inflating bag (SIB).

Study Design

Experienced and inexperienced caregivers were asked to mask ventilate a leak free manikin using the SIB before and after the training. Mask leak and pressures were measured using respiratory function monitoring. Pressures above 35 cm H₂O were considered excessive. Parameters were compared using a Wilcoxon non-parametric test.

Results

Before and after the short training, experienced caregivers had minimal median (IQR) mask leak (14 (3-75) vs. 3 (0-53)%; p<0.01). Inexperienced users had large leak which reduced from 51 (7-91)% before to 11 (2-71)% after training (p<0.01). Pressures above 35 cm H₂O hardly occurred in experienced caregivers (0 (0-5) vs. 0 (0-0)%; ns). In inexperienced caregivers this frequently occurred but decreased considerably after training (94 (46-100) vs. 2 (0-70)%; p<0.01).

Conclusion

A two-minute training of bag and mask ventilation was effective. This training could be incorporated into any training program.     

Household Ventilation May Reduce Effects of Indoor Air Pollutants for Prevention of Lung Cancer: A Case-Control Study in a Chinese Population

Background

Although the International Agency for Research on Cancer (IARC) has classified various indoor air pollutants as carcinogenic to humans, few studies evaluated the role of household ventilation in reducing the impact of indoor air pollutants on lung cancer risk.

Objectives

To explore the association between household ventilation and lung cancer.

Methods

A population-based case-control study was conducted in a Chinese population from 2003 to 2010. Epidemiologic and household ventilation data were collected using a standardized questionnaire. Unconditional logistic regression was employed to estimate adjusted odds ratios (OR_adj) and their 95% confidence intervals (CI).

Results

Among 1,424 lung cancer cases and 4,543 healthy controls, inverse associations were observed for good ventilation in the kitchen (OR_adj = 0.86, 95% CI: 0.75, 0.98), bedroom (OR_adj = 0.90, 95% CI: 0.79, 1.03), and both kitchen and bedroom (OR_adj = 0.87, 95% CI: 0.75, 1.00). Stratified analyses showed lung cancer inversely associated with good ventilation among active smokers (OR_adj = 0.85, 95% CI: 0.72, 1.00), secondhand smokers at home (OR_adj = 0.77, 95% CI: 0.63, 0.94), and those exposed to high-temperature cooking oil fumes (OR_adj = 0.82, 95% CI: 0.68, 0.99). Additive interactions were found between household ventilation and secondhand smoke at home as well as number of household pollutant sources.

Conclusions

A protective association was observed between good ventilation of households and lung cancer, most likely through the reduction of exposure to indoor air pollutants, indicating ventilation may serve as one of the preventive measures for lung cancer, in addition to tobacco cessation.     

Airway-centered interstitial fibrosis: etiology,clinical findings and prognosis

Background

Airway-centered Interstitial Fibrosis (ACIF) is a common pathologic pattern observed in our practice.

Objectives

The objectives of this study are to describe the causes associated with ACIF in a large sample of patients and its effect on survival.

Methods

A retrospective study in three centers of interstitial lung disease in São Paulo, between January of 1995 and December of 2012. The surgical lung biopsy specimens were reviewed by three pathologists. The clinical, functional and tomographic findings were analyzed by a standardized protocol.

Results

There were 68 cases of ACIF, most of them women. The mean age was 57 ± 12 yr. Dyspnea, cough, restrictive pattern at spirometry and oxygen desaturation at exercise were common. A reticular pattern with peribronchovascular infiltrates was found in 79% of the cases. The etiologies of ACIF were hypersensitivity pneumonitis in 29 (42.6%), gastroesophageal reflux disease in 17 (25.0%), collagen vascular disease in 4 (5.9%), a combination of them in 15 cases and idiopathic in 3 (4.4%). The median survival was 116 months (95% CI = 58.5 – 173.5). Lower values of oxygen saturation at rest, presence of cough and some histological findings - organizing tissue in the airways, fibroblastic foci and microscopic honeycombing - were predictors of worse survival.

Conclusions

ACIF is an interstitial lung disease with a better survival when compared with IPF. The main etiologies are HP and GERD. The oxygen saturation at rest, the presence of cough and some histological findings are predictors of survival.     

Surgical Outcomes and Prognostic Factors of T4 Gastric Cancer Patients without Distant Metastasis

Objective

To evaluate surgical outcomes and prognostic factors for T4 gastric cancer treated with curative resection.

Methods

Between January 1994 and December 2008, 94 patients diagnosed with histological T4 gastric carcinoma and treated with curative resection were recruited. Patient characteristics, surgical complications, survival, and prognostic factors were analyzed.

Results

Postoperative morbidity and mortality were 18.1% and 2.1%, respectively. Multivariate analysis indicated lymph node metastasis (hazard ratio, 2.496; 95% confidence interval, 1.218–5.115; p = 0.012) was independent prognostic factor.

Conclusions

For patients with T4 gastric cancer, lymph node metastasis was associated with poorer survival. Neoadjuvant chemotherapy or aggressive adjuvant chemotherapy after radical resection was strongly recommended for these patients.     

Cigarette smoke worsens lung inflammation and impairs resolution of influenza infection in mice

Background

Cigarette smoke has both pro-inflammatory and immunosuppressive effects. Both active and passive cigarette smoke exposure are linked to an increased incidence and severity of respiratory virus infections, but underlying mechanisms are not well defined. We hypothesized, based on prior gene expression profiling studies, that upregulation of pro-inflammatory mediators by short term smoke exposure would be protective against a subsequent influenza infection.

Methods

BALB/c mice were subjected to whole body smoke exposure with 9 cigarettes/day for 4 days. Mice were then infected with influenza A (H3N1, Mem71 strain), and analyzed 3 and 10 days later (d3, d10). These time points are the peak and resolution (respectively) of influenza infection.

Results

Inflammatory cell influx into the bronchoalveolar lavage (BALF), inflammatory mediators, proteases, histopathology, viral titres and T lymphocyte profiles were analyzed. Compared to smoke or influenza alone, mice exposed to smoke and then influenza had more macrophages, neutrophils and total lymphocytes in BALF at d3, more macrophages in BALF at d10, lower net gelatinase activity and increased activity of tissue inhibitor of metalloprotease-1 in BALF at d3, altered profiles of key cytokines and CD4+ and CD8+ T lymphocytes, worse lung pathology and more virus-specific, activated CD8+ T lymphocytes in BALF. Mice smoke exposed before influenza infection had close to 10-fold higher lung virus titres at d3 than influenza alone mice, although all mice had cleared virus by d10, regardless of smoke exposure. Smoke exposure caused temporary weight loss and when smoking ceased after viral infection, smoke and influenza mice regained significantly less weight than smoke alone mice.

Conclusion

Smoke induced inflammation does not protect against influenza infection.In most respects, smoke exposure worsened the host response to influenza. This animal model may be useful in studying how smoke worsens respiratory viral infections.     

Surgical mask to prevent influenza transmission in households: a cluster randomized trial

Background

Facemasks and respirators have been stockpiled during pandemic preparedness. However, data on their effectiveness for limiting transmission are scarce. We evaluated the effectiveness of facemask use by index cases for limiting influenza transmission by large droplets produced during coughing in households.

Methodology and Principal Findings

A cluster randomized intervention trial was conducted in France during the 2008–2009 influenza season. Households were recruited during a medical visit of a household member with a positive rapid influenza A test and symptoms lasting less than 48 hours. Households were randomized either to the mask or control group for 7 days. In the intervention arm, the index case had to wear a surgical mask from the medical visit and for a period of 5 days. The trial was initially intended to include 372 households but was prematurely interrupted after the inclusion of 105 households (306 contacts) following the advice of an independent steering committee. We used generalized estimating equations to test the association between the intervention and the proportion of household contacts who developed an influenza-like illness during the 7 days following the inclusion. Influenza-like illness was reported in 24/148 (16.2%) of the contacts in the intervention arm and in 25/158 (15.8%) of the contacts in the control arm and the difference between arms was 0.40% (95%CI: −10% to 11%, P = 1.00). We observed a good adherence to the intervention. In various sensitivity analyses, we did not identify any trend in the results suggesting effectiveness of facemasks.

Conclusion

This study should be interpreted with caution since the lack of statistical power prevents us to draw formal conclusion regarding effectiveness of facemasks in the context of a seasonal epidemic.

Trial Registration

clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00774774","term_id":"NCT00774774"}}NCT00774774     

Effects of exercise training on pulmonary vessel muscularization and right ventricular function in an animal model of COPD

Background

Right ventricular dysfunction in COPD is common, even in the absence of pulmonary hypertension. The aim of the present study was to examine the effects of high intensity interval training (HIIT) on right ventricular (RV) function, as well as pulmonary blood vessel remodeling in a mouse model of COPD.

Methods

42 female A/JOlaHsd mice were randomized to exposure to either cigarette smoke or air for 6 hours/day, 5 days/week for 14 weeks. Mice from both groups were further randomized to sedentariness or HIIT for 4 weeks. Cardiac function was evaluated by echocardiography and muscularization of pulmonary vessel walls by immunohistochemistry.

Results

Smoke exposure induced RV systolic dysfunction demonstrated by reduced tricuspid annular plane systolic excursion. HIIT in smoke-exposed mice reversed RV dysfunction. There were no significant effects on the left ventricle of neither smoke exposure nor HIIT. Muscularization of the pulmonary vessels was reduced after exercise intervention, but no significant effects on muscularization were observed from smoke exposure.

Conclusions

RV function was reduced in mice exposed to cigarette smoke. No Increase in pulmonary vessel muscularization was observed in these mice, implying that other mechanisms caused the RV dysfunction. HIIT attenuated the RV dysfunction in the smoke exposed mice. Reduced muscularization of the pulmonary vessels due to HIIT suggests that exercise training not only affects the heart muscle, but also has important effects on the pulmonary vasculature.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0117-y) contains supplementary material, which is available to authorized users.     

Famine in the Young and Risk of Later Hospitalization for COPD and Asthma

Background

Undernutrition during critical periods of growth and development may permanently affect lung physiology and function.

Objectives

To investigate whether acute undernutrition in childhood or young adulthood increases the risk of later hospitalization for obstructive airways disease, chronic obstructive pulmonary disease (COPD), or asthma.

Methods

We studied 7,841 women from Prospect-EPIC who experienced the 1944–45 Dutch famine between ages 0 and 21. Pulmonary outcomes were measured by registered hospital admissions and exposure-blinded computed tomography (CT) in a subgroup of 295 women. With Cox proportional hazard regression we explored effects of famine exposure on risk of hospitalization for obstructive airways disease, COPD, and asthma. With logistic regression we explored effects of famine on risk of CT evidence of pulmonary disease.

Results

Risks of hospitalization for obstructive airways disease, COPD, and asthma were increased after moderate famine exposure, and significantly increased after severe famine exposure: hazard ratios for obstructive airways disease were 1.31 (95% CI: 0.97 to 1.77) and 1.57 (95% CI: 1.10 to 2.23) respectively. Associations between famine exposure and hospitalization for COPD were stronger in ever-smokers than in never-smokers.

Conclusions

Acute undernutrition in childhood or young adulthood is associated with an increased risk of later COPD and asthma hospitalization, possibly through increased sensitivity for tobacco smoke.     

Capsaicin Cough Sensitivity and the Association with Clinical Parameters in Bronchiectasis

Background

Cough hypersensitivity has been common among respiratory diseases.

Objective

To determine associations of capsaicin cough sensitivity and clinical parameters in adults with clinically stable bronchiectasis.

Methods

We recruited 135 consecutive adult bronchiectasis patients and 22 healthy subjects. History inquiry, sputum culture, spirometry, chest high-resolution computed tomography (HRCT), Leicester Cough Questionnaire scoring, Bronchiectasis Severity Index (BSI) assessment and capsaicin inhalation challenge were performed. Cough sensitivity was measured as the capsaicin concentration eliciting at least 2 (C₂) and 5 coughs (C₅).

Results

Despite significant overlap between healthy subjects and bronchiectasis patients, both C₂ and C₅ were significantly lower in the latter group (all P<0.01). Lower levels of C₅ were associated with a longer duration of bronchiectasis symptoms, worse HRCT score, higher 24-hour sputum volume, BSI and sputum purulence score, and sputum culture positive for P. aeruginosa. Determinants associated with increased capsaicin cough sensitivity, defined as C₅ being 62.5 µmol/L or less, encompassed female gender (OR: 3.25, 95%CI: 1.35–7.83, P<0.01), HRCT total score between 7–12 (OR: 2.57, 95%CI: 1.07–6.173, P = 0.04), BSI between 5–8 (OR: 4.05, 95%CI: 1.48–11.06, P<0.01) and 9 or greater (OR: 4.38, 95%CI: 1.48–12.93, P<0.01).

Conclusion

Capsaicin cough sensitivity is heightened in a subgroup of bronchiectasis patients and associated with the disease severity. Gender and disease severity, but not sputum purulence, are independent determinants of heightened capsaicin cough sensitivity. Current testing for cough sensitivity diagnosis may be limited because of overlap with healthy subjects but might provide an objective index for assessment of cough in future clinical trials.