Pharmacophobia

Decisions concerning asthma management rely on assessment of respiratory problem severity, its known or projected course, and on the response of individual patients to their disease and treatment. The merits and the limitations of various methods for grading asthma, also called ROAD (reversible obstructive airways disease) or VOID variable obstructive intrabronchial disease), have been reviewed extensively,[1-5] but the conclusion that attempts to develop a multifactoxial ... index ... have been unsuccessful"[2, p 734] encourages additional efforts in this direction. In this issue of CHEST (see page 272), Teeter and Bleecker report that certain pulmonary function tests, the peak expiratory flow rate (PEF or PEFR), and the [FEV.sub.1], are more reliable than subjective perceptions for guiding the treatment of asthma. They also state that a 17% incidence of a "relatively asymptomatic airway obstruction" (if "obstruction" means simply a PEF below established norms) is of questionable significance and that "the long-term outcome of untreated or undertreated asthmatics (italics mine) is not known." The need to examine bronchodilator-induced reversibility for those with "asymptomatic obstruction" is not considered sufficiently in this report.

Both acute and chronic asthma are conventionally graded semiquantitatively as "mild, moderate, or severe."[3)(p4)] Numeric scales have been devised primarily for clinical research, while it is still recognized that "there is no universally accepted and validated measure of asthma severity."[6] Even the elementary question of the mathematical, possibly exponential or logarithmic, relationship between symptom scores and pulmonaly function tests, in particular the plethysmographic computations of airways resistance and conductance,[5,7] has not been examined adequately.

The realization that clinical indexes do not reflect precisely the degree of ventilatory impairment in asthma[7] has led to a search for a convenient and economic way to monitor airflow variability.[2-5] Despite the limitations of the original Wright peak flowmeter (Ferraris Medical; Holland, NY) (in use for nearly 30 years) and of several subsequent similar devices, including the newly developed computerized version, which are markedly effort-dependent and detect only abnormalities in larger airways caliber,[4,5] they are widely employed. The current authoritative "Consensus Report" and the "Guidelines" for asthma treatment recommend testing PEF in the medical office, the emergency room (dismissing the problem that during an acute attack patients may not be able to blow), and at home.[3,4] At work PEF may help detect or raise the suspicion of occupational asthma.[9] But there have also been some negative or critical communications. A survey in Scotland determined that "prescribing peak flow meters ... is unlikely to improve mortality and morbidity."[10] Supporting this conclusion is the statement that PEF measurements are "not suitable" for the initial diagnosis of asthma, and that monitoring PEF is "not based on any scientific evidence."[11] From Australia it was reported[12] that forced mid-expiratory flow (FEF[25-75)], tested twice weekly reflected the course of asthma accurately, supplemented by PEF self-measurements twice daily. In fact, "if measurements of flow rates at low lung volumes (FEF[50] FEF[25-75] are not performed ... patients with pathophysiologic abnormalities ... linked to the small airways may be underdiagnosed."[4)(p19)]

Obviously the schedule of testing ideally has to be based on an estimate of the rapidity of changes and for a thorough monitoring the frequency of measurements must equal or exceed the anticipated variability cycle."[5] Records of PEF before and after bronchodilator and/or anti-inflammatory therapy, as well as in the course of natural or experimental bronchoconstrictive challenges, are, essential[2,9] for appropriate protective and therapeutic action. The frequent self-measurement of PEF serves the additional purpose of patient education, the value of which has been repeatedly emphasized.[2(p22),3,4,10(p1093),13] Even though several studies have found a lack of a significant correlation between subjective symptoms and pulmonary function measurements,[1-3,5,7] it has been noted[14] that after checking their PEF at its highs and lows several times daily for 10 to 15 days, patients, including young children, learn to predict their PEF scores before they measure them (author's unpublished observations; 1959-1997). Such fairly accurate self-perception of ventilatory impairment is more in reference to "established personal best values"[3(pp 20-21)] than predicted "normal" ranges.

Like the personal perception of "disease," instrumental tests of pulmonary function are subject to multiple influences and, certainly, "instructions ... do not guarantee" maximum performance.[13] Motivation will have to be ascertained and its positive (a desire to excel and to hide malfunction) as well as negative (an attempt to appear "sicker") effect be noted. Mood has not been found to correlate with either symptoms or PEF, although, predictably, increased symptoms were secondarily associated with a "less pleasant mood."[1] Individual responses to sudden PEF changes also vary markedly. Some athletes, professional singers, wind instrument players, and others with high ventilatory requirements may rush for additional treatment if their PEF drops only by 10%, say, from 500 to 450 L/min. Others, leading a relatively sedentary life, may ignore a PEF below 60% predicted, especially if they are reluctant to take medication to the point of "pharmacophobia," or are unwilling to reduce allergenic exposures such as that to a household pet (author's unpublished observations; 1957-1997).

Evidently neither symptom scores nor ventilatory function measurements provide sufficient guidelines about when and how to treat asthma. Treatment of human beings relying only on numbers can be analogous to an appraisal of a great painting based on the milligrams of each pigment it contains. 14What is needed is patient education, to improve each person's judgment and the capacity for self-care. The current flood of data, with 90,360 documents on the World Wide Web matching the word asthma[15] and a reported "loss of trust" for physicians turning into "acute suspicion," has prompted some journalistic comments about "prescribing just what the patient ordered."[15] If this were to mean total patient autonomy, we known that it could result in serious undertreatment, or overtreatment that might interfere with physiologic regulatory, cybernetic[16] processes and actually amplify asthma.[17] The logical solution, of course is the establishment of a close rapport and a workable line of communications between patients and the health-care team. Securely supported by the necessary technical and laboratory data, clinicians must continue to listen to their patients' personal perceptions and to make consistent efforts to understand their "subjective," all too human, expectations and needs.

REFERENCES

[1] Apter AJ, Affleck G, Reisine ST, et al. Perception of airway obstruction in asthma: sequential daily analyses of symptoms, peak expiratory flow rate, and mood. J Allergy Clin Immunol 1997; 99:605-12

[2] Spector SL, Nicklas RA, eds. Practice parameters for the diagnosis and treatment of asthma. J Allergy Clin Immunol 1995; 96(suppl):732-36

[3] National Institutes of Health. Expert Panel. Guidelines for the diagnosis and management of asthma. Publ. No. 91-3042. Bethesda, Md: NIH, 1991

[4] National Institutes of Health. International Report. International consensus report on diagnosis and management of asthma. Publ. No. 92-3091. Bethesda, Md: NIH, 1992

[5] Falliers CJ. Interpretation of consecutive lung function tests for asthma. Ann Allergy 1972; 30:443-49

[6] Wahlgren DR, Hovell MF, Matt GE, et al. Toward a simplified measure of asthma severity for applied research. J Asthma 1997; 34:291-303

[7] McFadden RE jr. Pulmonary structure, physiology, and clinical correlates in asthma (Chapter 26). In: Middleton E Jr, Reed CE, Ellis ET, et al, eds. Allergy principles and practice. 4th ed. St. Louis: Mosby, 1993; 672-93

[8] Quirce S, Contreras G, Moran O, et al. Laboratory add clinical evaluation of a portable computerized peak flow meter. J Asthma 1997; 34:305-12

[9] Chan-Yeung M (Chair). ACCP consensus statement: assessment of asthma in the workplace. Chest 1995; 108: 1084-1117

[10] Grampian Asthma Study of Integrated Care: effectiveness of routine self monitoring of peak flow in patients with asthma. BMJ 1994; 308:564-67

[11] Sly PD. Peak expiratory flow monitoring in pediatric asthma: is there a role? j Asthma 1996; 33:277-87

[12] Ferguson AC. Persisting airway obstruction in asymptomatic children with asthma with normal peak expiratory flow rates. J Allergy Clin Immunol 1988; 82:19-22

[13] Harm DL, Marion RJ, Kotses H, et al. Effect of subject effort on pulmonary function measures: a preliminary investigation. J Asthma 1984; 21:295-98

[14] Falliers CJ. Asthma research: an impasse or Tower of Babel [editorial]? J Asthma 1988; 25:317-19

[15] Stolberg SG. Now, prescribing just what the patient ordered. New York Times, Aug. 10, 1997: E-3

[16] Falliers CJ. Asthma and cybernetics (or why doesn't everyone have asthma?). J Allergy 1966; 38:264-67

[17] Falliers CJ. Amplify asthma [letter]? N Engl J Med 1970; 283:599

Director, Allergy and Asthma Clinic, PC; Clinical Professor, internal Medicine and Pediatrics Departments, University of Colorado School of Medicine.

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