Rate of response of individual asthma control measures varies and may overestimate asthma control: an analysis of the goal study

BACKGROUND

Using a composite measure based on clinical outcomes, the GOAL study showed that achievement of Total Control of asthma was time dependent with the proportion of controlled patients continuing to rise through the year-long study. Taking data from this study, we compared time taken to achieve Total Control with time taken to achieve total control of each individual clinical criterion on treatment with salmeterol/fluticasone propionate (SFC) or fluticasone propionate (FP) alone.

METHODS

Time to achieving total control of individual outcomes (day-time symptoms, night-time awakenings, rescue medication use, PEF > or =80% predicted every day) were analyzed by Kaplan Meier plots and compared with achievement of composite Total Control.

RESULTS

Night-time awakenings responded most rapidly and daytime symptoms took longest to respond. After 12 weeks, the proportion of patients who achieved control of any individual clinical criterion was higher than the proportion who achieved control when using the composite outcome (no night-time awakenings achieved by 73% with SFC and 65% with FP; PEF > or =80% predicted every day, 55% and 45% respectively; no rescue usage 46% and 35% respectively; and no daytime symptoms, 35% and 24% respectively, compared with Total Control, 23% and 14% respectively). In every measure except night-time awakenings, more rapid responses were seen for SFC compared with FP alone.

CONCLUSIONS

Speed of response of individual asthma measures varies and evaluation of control using any single measure overestimates total asthma control. Treatment should be continued until composite control is reached, rather than control of individual outcomes.

A robustness-based approach to systems-oriented drug design

Many potential drugs that specifically target a particular protein considered to underlie a given disease have been found to be less effective than hoped, or to cause significant side effects. The intrinsic robustness of living systems against various perturbations is a key factor that prevents such compounds from being successful. By studying complex network systems and reformulating control and communication theories that are well established in engineering, a theoretical foundation for a systems-oriented approach to more effectively control the robustness of living systems, particularly at the cellular level, could be developed. Here, I use examples that are based on existing drugs to illustrate the concept of robustness, and then discuss how a greater consideration of the importance of robustness could influence the design of new drugs that will be intended to control complex systems.

Multicomponent therapeutics for networked systems

Therapeutic regimens that comprise more than one active ingredient are commonly used in clinical medicine. Despite this, most drug discovery efforts search for drugs that are composed of a single chemical entity. A focus in the early drug discovery process on identifying and optimizing the activity of combinations of molecules can result in the identification of more effective drug regimens. A systems perspective facilitates an understanding of the mechanism of action of such drug combinations.

Laryngeal findings in users of combination corticosteroid and bronchodilator therapy

EDUCATIONAL OBJECTIVE

At the conclusion of this article, the readers should be able to 1) describe the laryngeal findings in patients who use combination therapy for asthma, 2) discuss the mechanism of laryngeal irritation from the use of inhalers, and 3) describe possible mechanisms for reducing laryngeal irritation and secondary dysphonia from the use of inhalers.

OBJECTIVES

To describe voice changes and laryngeal findings in patients who are started on combination corticosteroid and bronchodilator therapy in the form of a dry powder inhaler (DPI).

STUDY DESIGN

Retrospective, single-subject design.

METHODS

Retrospective review of 10 consecutive patients meeting inclusion criteria, who presented at the voice center with more than 4 weeks of dysphonia after being started on a combination form of asthma medication for control and maintenance therapy. All patients were nonsmokers and without history of previous identification or excision of vocal pathology. All patients were treated previously with a proton pump inhibitor for gastroesophageal reflux. Laryngeal videostroboscopic evaluations were performed on all patients. Patients were asked to complete a questionnaire regarding their perceived voice change and history of medical maintenance therapy for asthma.

RESULTS

Dysphonia was present in the patients selected for greater than 4 weeks. Patients had been switched to combination therapy after previously using traditional two-drug asthma regimens. In eight of nine patients, the vocal folds demonstrated areas of hyperemia, with plaque-like changes on the surface mucosa. Reduced amplitude of vibration and a reduction in mucosal wave propagation were present on videostroboscopy. Questionnaires revealed that all patients were initiated on combination DPI treatment within the last 6 months.

CONCLUSIONS

Dysphonia caused by a change in the surface mucosa is a side effect from the use of DPI therapy for asthma. The high-impact force during inhalation of the medication and carrier leads to deposition of particles in the upper airway. We believe the extent of mucosal irritation can be minimized by patient education in the proper delivery of DPI. In some cases, however, return of the two medications delivered separately was necessary. The irritation of the laryngeal mucosa and return of normal vibratory parameters occurred in all patients.