Blood eosinophil count correlates with severity of respiratory failure in life-threatening asthma and predicts risk of subsequent exacerbations

BACKGROUND

An elevated blood eosinophil count when asthma is stable predicts exacerbations and therapeutic response to corticosteroids or biologics targeting eosinophils. Few studies have examined the prognostic value of blood eosinophils measured at exacerbation.

AIM

To elucidate the relationship between a spot blood eosinophil count-measured at the onset of a life-threatening asthma exacerbation-with indices of exacerbation severity and risk of subsequent exacerbations.

METHODS

Real-world, retrospective review of all life-threatening asthma cases admitted at 4 public hospitals in Singapore between 2011-2015. We assessed the trends and correlations between blood eosinophil count on admission with arterial blood gas values, duration of mechanical ventilation, and risk of death, hypoxic ischemic encephalopathy or respiratory arrest. Risk of future exacerbations among survivors was modelled using Cox regression and survival curves.

RESULTS

There were 376 index life-threatening exacerbations with median blood eosinophil count (5-95th percentiles) of 0.270 × 10⁹ /L (0-1.410 × 10⁹ /L). Arterial pH decreased and PCO₂ increased with increasing eosinophil count. Duration of mechanical ventilation and risk of death, hypoxic ischaemic encephalopathy or respiratory arrest did not vary with eosinophils. Among 329 survivors who were followed-up over a median of 52 months, blood eosinophils ≥1.200 × 10⁹ /L was associated with an increased hazard of emergency visits and/or admissions for asthma (hazard ratio 1.8, 95% confidence interval 1.1-2.9, P = .02).

CONCLUSION

In this study of life-threatening asthma, we found that a spot blood eosinophil count correlates with severity of respiratory failure and predicts risk of subsequent exacerbations.

Factors Associated with Dysfunctional Breathing in Patients with Difficult to Treat Asthma

BACKGROUND

Understanding of dysfunctional breathing in patients with difficult asthma who remain symptomatic despite maximal inhaler therapy is limited.

OBJECTIVE

We characterized the pattern of dysfunctional breathing in patients with difficult asthma and identified possible contributory factors.

METHODS

Dysfunctional breathing was identified in patients with difficult asthma using the Nijmegen Questionnaire (score >23). Demographic characteristics, asthma variables, and comorbidities were assessed. Multivariate logistic regression was performed for dysfunctional breathing, adjusted for age, sex, body mass index, and airflow obstruction.

RESULTS

Of 157 patients with difficult asthma, 73 (47%) had dysfunctional breathing. Compared with patients without dysfunctional breathing, those with dysfunctional breathing experienced poorer asthma status (symptom control, quality of life, and exacerbation rates) and greater unemployment. In addition, more frequently they had elevated sino-nasal outcome test scores, anxiety, depression, sleep apnea, and gastroesophageal reflux. On multivariate analysis, anxiety (odds ratio [OR], 3.26; 95% CI, 1.18-9.01; P = .02), depression (OR, 2.8; 95% CI, 1.14-6.9; P = .03), and 22-item sino-nasal outcome test score (OR, 1.03; 95% CI, 1.003-1.05; P = .03) were independent risk factors for dysfunctional breathing.

CONCLUSIONS

Dysfunctional breathing is common in difficult asthma and associated with worse asthma status and unemployment. The independent association with psychological disorders and nasal obstruction highlight an important interaction between comorbid treatable traits in difficult asthma.

Elevated total serum immunoglobulin E (>1000 IU/mL): implications?

Atopic eczema, allergic broncho-pulmonary aspergillosis, helminthic infections and rare primary immunodeficiencies are known to elevate total serum immunoglobulin E (IgE) above 1000 IU/mL. However, of 352 patients with IgE >1000 IU/mL seen in our hospital over a 5-year period, less than 50% had these conditions. Markedly elevated IgE levels in the rest of the patients were associated with asthma, allergic rhinitis and food allergy, instances where the test is of limited diagnostic utility.

Characteristics of non-smoking adult asthma patients with chronic airflow limitation

OBJECTIVE

Chronic airflow limitation (CAL) can develop in a subgroup of patients with asthma. Characterising these patients is important because reduced lung function is a risk factor for adverse asthma outcomes. We hypothesised that heterogeneity in patients with CAL may be influenced by age at asthma onset. We first compared never-smoking asthma patients with and without CAL, and subsequently examined the differences between patients with late and early-onset asthma within the CAL cohort.

METHODS

Patients seen in our hospital's respiratory clinic between 1 Jan 2015 and 31 December 2015 were recruited to the study. CAL was defined as post-bronchodilator forced expiratory volume in 1 second (FEV1)<80% predicted, in the presence of post-bronchodilator ratio <70%. Variables independently associated with CAL were determined using a multivariate logistic regression model. Comparisons between patients with late-onset asthma (age ≥18 years) and early-onset asthma were made within the CAL cohort.

RESULTS

247 patients were included in the study. Age was the only variable independently associated with CAL after regression analysis, with an increase in odds of 3.8% (95% CI 0.4-7.3%) for every 1 year increase in age, p = 0.027. 63.2% of patients with CAL had late-onset asthma. Compared to patients with early-onset asthma, those with late-onset asthma had higher fractional exhaled nitric oxide levels (43 ± 32 ppb vs 20 ± 8 pb, p = 0.008).

CONCLUSIONS

An increase in age is associated with CAL in never-smoking asthma patients. In addition, age at asthma onset appears to influence airway inflammation in patients with CAL.

Do we need transbronchial lung biopsy if we have bronchoalveolar lavage Xpert® MTB/RIF?

BACKGROUND

Studies evaluating the role of transbronchial lung biopsy (TBLB) in diagnosing pulmonary tuberculosis (PTB) date back decades and have shaped current practice. However, with the recent advent of bronchoalveolar lavage (BAL) Xpert® MTB/RIF, it is time to re-evaluate the role of TBLB.

OBJECTIVE

To assess the impact of BAL and TBLB with the addition of BAL Xpert on diagnostic PTB yields and time to treatment initiation in sputum-scarce or acid-fast bacilli (AFB) smear-negative PTB patients.

METHODS

We retrospectively reviewed all sputum-scarce or AFB smear-negative patients who underwent both BAL and TBLB for suspected PTB between March 2011 and October 2013. Xpert was performed on all BAL specimens.

RESULTS

Of 158 patients included in our analysis, 44 were culture-proven PTB. Ninety-four per cent of the patients had AFB smear-negative BAL samples. The sensitivity and specificity of Xpert in AFB smear-negative BAL samples were respectively 60% and 98%. The addition of BAL Xpert expedited the institution of PTB treatment while having diagnostic yields comparable to those of conventional BAL with TBLB.

CONCLUSIONS

The use of BAL Xpert may obviate the need for TBLB in increasing the diagnostic yield of PTB in sputum-scarce or AFB smear-negative patients.