The article by Leal Hernández et al is of interest for several reasons. Firstly, few studies are available on inhalation technique in patients with chronic obstructive pulmonary disease (COPD) seen in primary care centers. Noteworthy among these studies is that by Benito et al in 1997. These authors found that at three health centers in Burgos, 52% of the patients in a group of participants who had asthma or COPD used inhalers incorrectly.1 Secondly, and more importantly, this was the first interventional study in the primary care setting in Spain to examine inhalation technique in patients with COPD.
The question the researchers posed to study the issue is attractive: should written or verbal information be chosen for interventions intended to teach inhalation technique? However, the authors faced a number of obstacles that kept them from reaching conclusions with practical applications.
Studies of inhalation technique are not easy to carry out. Most such studies are limited to describing compliance with previously agreed criteria. In Spain, the recommendations of the Spanish Society of Respiratory Diseases (SEPAR)2 are usually followed. The problem here is that these criteria have not been validated. The SEPAR guidelines claim that each step in the instructions for inhalation technique is supported by published studies, but no references are given in the guidelines themselves. In fact, it is fundamental to know whether the particles of the drug are appropriately dispersed in the gas vehicle, impact as little as possible on the pharynx, are delivered to the lungs at a suitable rate, and are diffused correctly. The fraction of the dose exhaled should be likewise contact the pharynx as little as possible. The gold standard for studies of pulmonary diffusion continues to be scintigraphy with isotope-labeled drugs.
Because such studies are impractical, systems that make it possible to monitor the steps in the inhalation process more easily have become common. Two studies are worth mentioning in this connection. De Blaquiere et al, in 1989, reported the use of a monitored system that determined inspiration, inhaler activation and duration of breath-holding.3 Cimas et al validated a checklist for inhalation technique for pressurized canister inhalers and dry powder inhalers ("turbohalers"), using 2 electronic monitoring systems as their gold standard. This latter study is of greater interest, as it describes the only instrument validated for use in Spanish.4
This was not the case in the study by Leal Hernández et al, who used a nonvalidated test for which no information is given in the Material and Methods section regarding validity (sensitivity and specificity) or intraobserver reliability. (It would have been advisable to include a second observer to determine interobserver reliability.) These shortcomings raise questions about the applicability of the method these authors used.
Unfortunately, this was not the only problem with the study. Although of less concern (because it does not affect the results), it should be pointed out that the study population might not have consisted exclusively of patients with COPD. Why? Because no reversibility test was done to distinguish between patients with asthma and those with COPD among patients with spirometric findings indicative of obstruction. In the authors' defense, it should be said that it can be difficult to distinguish between these two entities. This is why many studies make no distinction between the two kinds of patient, and include both under the heading of chronic obstructive lung disease. In any case, I believe that selecting men between 60 and 75 years of age may have helped keep the number of patients with asthma low, although patients who had never been smokers but who had findings of obstruction should perhaps be analyzed separately.
Finally, the greatest drawback of the study needs to be considered. The authors state in the Discussion section that there were no differences between using written information (which is cheaper) and verbal information (which takes more time). However, it is hard to avoid the suspicion of a type II (beta) error; consequently, the only thing that can be said is that no differences between the two interventions could be established. This, however, does not rule out that such differences may in fact exist. Because the authors did not indicate the power of the study design in the Materials and Methods section, we cannot share their conclusions. What is clearly worth taking into account, however, is the authors' conclusion that verbal and written information are both superior to the control condition (no intervention). Nevertheless, it is difficult to answer the question raised in the Introduction: is information supplied verbally as effective as information supplied in writing?
To conclude, it is important to understand the role of teaching inhalation technique to patients with COPD in the context of educational measures for patients with a chronic disease. Although education for patients with asthma has been shown effective (improved quality of life and pulmonary function, and lower costs),5 this has not been the case for COPD. Respiratory rehabilitation seems to improve quality of life and exercise tolerance, and written instructions about managing exacerbations may decrease the use of rescue medication (beta 2 agonists), facilitating early treatment of exacerbations with antibiotics and oral corticosteroids.6 In this regard, teaching inhalation technique should be seen as one more element in educational programs, along with counseling to quit smoking, incentives to exercise, and advice about nutrition and eating habits. However, teaching inhalation technique does not always improve compliance, and in patients with COPD, the lack of variation in symptoms (compared to asthma) along with the lack of perceived improvement, appear to lead to low levels of compliance. However, avoiding the overuse or underuse of inhalation treatment is useful, a factor not considered in the aims of the study by Leal Hernández et al. In contrast to asthma, the aim for patients with COPD is for the patient to enjoy an acceptable degree of health while avoiding the appearance of iatrogenic illnesses, given that the course of the disease cannot be changed (unless the patient stops smoking or uses oxygen therapy, if indicated). Naturally, the skillful performance of inhalation technique is of relevance for these patients.
Ultimately, the questions we must ask are these: what is the minimum amount of education that will be effective, and how can compliance be improved? Another important issue is of course how to obtain the greatest benefit from the time invested in teaching our patients how to use inhalers.
The efforts of Leal Hernández et al should be appreciated in an area where further research is needed along the lines of the study these authors have published. It is hoped that their efforts will lead to further interventional studies in primary care in the field of respiratory disease.
Key Points
* Interventional studies on the use of inhalation techniques should use validated evaluation systems. Scintigraphy remains the gold standard.
* A method based on electronic monitoring has been validated in Spanish and is available to test performance of inhalation techniques.
* The study this editorial comments on does not prove that there are differences between written and verbal instructions, nor does it prove that no difference exists.
* Teaching inhalation technique is part of patient education for persons with chronic obstructive pulmonary disease.
* Correct inhalation technique does not ensure compliance with therapy. Other factors are the perceived response to bronchodilation treatment and the patient's attitudes regarding the need for bronchodilators.
* Studies designed to evaluate educational interventions for patients with COPD are needed.
