Longitudinal changes in airflow limitation and airway hyperresponsiveness in patients with stable asthma

Multidimensional analyses of long-term clinical courses of asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are chronic respiratory disorders involving obstructive airway defects. There have been many discussions on their similarities and differences. Although airflow limitation expressed as forced expiratory volume in one second (FEV(1)) has been considered to be the main diagnostic assessment in both diseases, it does not reflect the functional impairment imparted to the patients by these diseases. Therefore, multidimensional approaches using multiple measurements in assessing disease control or severity have been recommended, and multiple endpoints in addition to FEV(1) have been set recently in clinical trials so as not to miss the overall effects. In particular, as improving symptoms and health status as well as pulmonary function are important goals in the management of asthma and COPD, some patient-reported measurements such as health-related quality of life or dyspnea should be included. Nonetheless, there have been few reviews on the long-term clinical course comparing asthma and COPD as predicted by measurements other than airflow limitation. Here, we therefore analyzed and compared longitudinal changes in both physiological measurements and patient-reported measurements in asthma and COPD. Although both diseases showed similar long-term progressive airflow limitation similarly despite guideline-based therapies, disease progression was different in asthma and COPD. In asthma, patient-reported assessments of health status, disability and psychological status remained clinically stable over time, in contrast to the significant deterioration of these parameters in COPD. Thus, because a single measurement of airflow limitation is insufficient to monitor these diseases, multidimensional analyses are important not only for disease control but also for understanding disease progression in asthma and COPD.

Analysis of longitudinal changes in the psychological status of patients with asthma

Significant relationships between the psychological status and poor asthma outcomes are often reported. However, most of these studies are cross-sectional and none have evaluated how the psychological status progresses over time during the management of asthma patients. Therefore, we examined the longitudinal changes in the psychological status of asthma patients, and compared them with changes in other clinical measurements. Eighty-seven outpatients with stable asthma after 6 months of treatment were enrolled in this study. The psychological status was evaluated using the Hospital Anxiety and Depression Scale (HADS), the health status using the Asthma Quality of Life Questionnaire (AQLQ) and the St. George's Respiratory Questionnaire (SGRQ). The patient's pulmonary function, peak expiratory flow values and airway hyperresponsiveness were measured at entry and every year thereafter over a 5-year period. Using mixed effects models to estimate the slopes, the HADS anxiety and depression scores did not change significantly over time (p=0.71 and 0.72, respectively). The changes in the HADS scores correlated noticeably with changes in the AQLQ and SGRQ scores, but not with changes in the physiological measurements. The baseline HADS anxiety and depression scores were significantly correlated to the subsequent annual changes in each measurement. The psychological status remained clinically stable over the 5-year study period in patients with stable asthma. Changes in the psychological status were significantly correlated to changes in the health status. The baseline HADS scores were a useful indicator in detecting patients who would show subsequent deterioration in their psychological status.

Inhibition of arginase I activity by RNA interference attenuates IL-13-induced airways hyperresponsiveness

Increased arginase I activity is associated with allergic disorders such as asthma. How arginase I contributes to and is regulated by allergic inflammatory processes remains unknown. CD4+ Th2 lymphocytes (Th2 cells) and IL-13 are two crucial immune regulators that use STAT6-dependent pathways to induce allergic airways inflammation and enhanced airways responsiveness to spasmogens (airways hyperresponsiveness (AHR)). This pathway is also used to activate arginase I in isolated cells and in hepatic infection with helminths. In the present study, we show that arginase I expression is also regulated in the lung in a STAT6-dependent manner by Th2-induced allergic inflammation or by IL-13 alone. IL-13-induced expression of arginase I correlated directly with increased synthesis of urea and with reduced synthesis of NO. Expression of arginase I, but not eosinophilia or mucus hypersecretion, temporally correlated with the development, persistence, and resolution of IL-13-induced AHR. Pharmacological supplementation with l-arginine or with NO donors amplified or attenuated IL-13-induced AHR, respectively. Moreover, inducing loss of function of arginase I specifically in the lung by using RNA interference abrogated the development of IL-13-induced AHR. These data suggest an important role for metabolism of l-arginine by arginase I in the modulation of IL-13-induced AHR and identify a potential pathway distal to cytokine receptor interactions for the control of IL-13-mediated bronchoconstriction in asthma.

Longitudinal deteriorations in patient reported outcomes in patients with COPD

Goals of effective management of patients with chronic obstructive pulmonary disease (COPD) include relieving their symptoms and improving their health status. We examined how such patient reported outcomes would change longitudinally in comparison to physiological outcomes in COPD. One hundred thirty-seven male outpatients with stable COPD were recruited for the study. The subjects health status was evaluated using the St. George's Respiratory Questionnaire (SGRQ) and the Chronic Respiratory Disease Questionnaire (CRQ). Their dyspnoea using the modified Medical Research Council (MRC) scale and their psychological status using the Hospital Anxiety and Depression Scale (HADS) were assessed upon entry and every 6 months thereafter over a 5-year period. Pulmonary function and exercise capacity as evaluated by peak oxygen uptake (VO2) on progressive cycle ergometry were also followed over the same time. Using mixed effects models to estimate the slopes for the changes, scores on the SGRQ, the CRQ, the MRC and the HADS worsened in a statistically significant manner over time. However, changes only weakly correlated with changes in forced expiratory volume in 1s (FEV(1)) and peak (VO2). We demonstrated that although changes in pulmonary function and exercise capacity are well known in patients with COPD, patient reported outcomes such as health status, dyspnoea and psychological status also deteriorated significantly over time. In addition, deteriorations in patient reported outcomes only weakly correlated to changes in physiological indices. To capture the overall deterioration of COPD from the subjective viewpoints of the patients, patient reported outcomes should be followed separately from physiological outcomes.

An Increase in Bronchial Responsiveness Is Associated with Continuing or Restarting Smoking

RATIONALE

Bronchial responsiveness (BHR) has been found to be associated with smoking, atopy, and lower lung function in cross-sectional studies, but there is little information on determinants of change in adults.

OBJECTIVES

To analyze change in bronchial responsiveness in an international longitudinal community study.

METHODS

The study was performed in 3,993 participants in the European Community Respiratory Health Survey who had bronchial responsiveness measured in 1991-1993, when aged 20 to 44 yr, and in 1998-2002.

MEASUREMENTS

Bronchial responsiveness was assessed by methacholine challenge. Serum samples were tested for total IgE, and for specific IgE to four common allergens. Smoking information was obtained from detailed administered questionnaires. Change in bronchial responsiveness was analyzed by change in IgE sensitization, smoking, and lung function, with tests of interaction terms with age and sex.

MAIN RESULTS

Continuing and restarting smokers had increasing bronchial responsiveness, approximately equivalent to a mean reduction in PD20 of 0.68 and 0.75 doubling doses, respectively, over 10 yr, in addition to a small increase explained by decline in FEV1. No other risk factor for change in bronchial responsiveness was identified.

CONCLUSIONS

Smoking is a risk factor for increasing bronchial responsiveness over and above the effect of decreasing lung function. Neither baseline IgE sensitization nor change in sensitization was shown to be a risk factor for increasing BHR, the latter possibly due to little overall increase or decrease in sensitization.

Exercise Capacity Deterioration in Patients With COPD

BACKGROUND

Although exercise capacity is an important outcome measure in patients with COPD, its longitudinal course has not been analyzed in comparison to the change in pulmonary function.

PURPOSES

To examine how exercise capacity would deteriorate over time in patients with COPD, and what factors would contribute to it.

METHODS

A total of 137 male outpatients with moderate-to-very-severe COPD were examined. The average age was 69.0 +/- 6.6 years (+/- SD), and the mean postbronchodilator FEV(1) was 45.9 +/- 15.4% predicted. Progressive cycle ergometry and pulmonary function testing were performed at entry, and every 6 months thereafter over 5 years. Due to the presence of missing data, a mixed-effect model analysis was then used to estimate the longitudinal changes in various clinical parameters.

RESULTS

Peak oxygen uptake (Vo(2)), peak minute ventilation (Ve), and peak tidal volume (Vt) during exercise declined significantly over time (p < 0.0001), which was no less rapid than the deterioration in FEV(1). The mean decline rates for peak Vo(2) were 32 +/- 60 mL/min/yr and 0.5 +/- 1.0 mL/min/kg/yr. Multiple regression analysis revealed that the changes in peak Ve, peak Vt, and peak respiratory rates were significant predictors for the change in peak Vo(2).

CONCLUSION

We demonstrated clear evidence of measurable and progressive deterioration in exercise capacity in COPD patients, which was no less rapid than the decline in airflow limitation. Dynamic ventilatory constraints during exercise also deteriorated over time, which most significantly contributed to this exercise capacity deterioration. In addition to pulmonary function, the longitudinal follow-up of exercise capacity is important not to miss the overall deterioration in COPD.

Longitudinal changes in patient vs. physician-based outcome measures did not significantly correlate in asthma

BACKGROUND AND OBJECTIVE

Although improving health status is one important aim in managing asthmatic patients, few studies have evaluated their health status longitudinally. Therefore, we examined longitudinal changes in health status of asthma patients, and compared them with changes in physiological measures.

METHODS

Eighty-seven outpatients with stable asthma after 6 months of treatment were recruited. Health status using the Asthma Quality of Life Questionnaire (AQLQ) and the St. George's Respiratory Questionnaire (SGRQ), pulmonary function, peak expiratory flow (PEF) values, and airway hyperresponsiveness (AHR) were evaluated at entry and every year over a 5-year period.

RESULTS

Using mixed effects models to estimate the slopes, the overall AQLQ score declined statistically at a mean rate of 0.06 units/year (P=.0091). However, this decline did not reach a clinically significant level at 5 years. The total SGRQ score did not change significantly (P=.54). Although the forced expiratory volume in 1 sec declined at a mean rate of 53 mL/year, the PEF variability and AHR improved significantly.

CONCLUSION

Health status was clinically stable over the 5-year study period in patients with asthma, which contrasted with the changes in the physiological outcome measures. As a patient centered outcome measure, health status should be followed separately.

Overlap of asthma and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Asthma and chronic obstructive pulmonary disease (COPD) are both defined by the presence of airflow obstruction, but they present distinguishing differences in terms of both risk factors and clinical phenotypes. Yet it is quite common in the clinical setting to observe patients with asthma showing COPD-like phenotypes, and vice versa, making it a priority to search for optimal prevention, treatment, and management strategies for these cases of coexisting lung obstructive diseases.

RECENT FINDINGS

Recent studies have provided further evidence of strong epidemiologic and clinical links between asthma and COPD. Adult subjects with active asthma are as much as 12 times more likely to acquire COPD over time than subjects with no active asthma. Signs identifying patients with asthma predisposed to developing COPD may already be present at the early stages of the disease, a finding with potential implications for prevention of COPD. In addition to spirometry and other pulmonary function tests (such as measurements of residual volume and diffusing capacity of the lung for carbon monoxide), recent evidence suggests that the assessment of type and degree of airway remodeling and the evaluation of inflammatory markers might prove useful in the future to characterize phenotypically patients with coexisting asthma and COPD.

SUMMARY

The nature of the association between asthma and COPD remains unclear and open to discussion. Further research is required to develop effective management algorithms for patients with multiple obstructive lung diseases, determine to what extent early treatment and optimal management of asthma may protect against progression into COPD, and identify genetic markers of individual susceptibility to specific lung disease phenotypes and pharmacologic treatments.