A VERSATILE TEST FOR ASTHMA CONTROL

According to the literature, many asthma patients are undertreated because they and their physicians overestimate their degree of symptom control. In an attempt to quantify asthma control more accurately, Nathan et al developed the Asthma Control Test (ACT)—a patient-based assessment of asthma control that can be used with or without concomitant lung function tests.

Patients completed a 22-item survey, after which prebronchodilator FEV1 was recorded. An asthma specialist interviewed each patient and performed spirometry; the specialist then rated the level of asthma control using a 5-point scale. Survey items with the greatest validity in detecting differences between physicians’ and patients’ perceptions of asthma control were identified, leading to a finalized subset of five items.

Four hundred seven asthma patients completed the study. According to the specialists’ ratings, asthma was well controlled in 52.2% of the patients and completely controlled in 18.1%. There was a moderate-to-low correlation between ACT score, FEV1, and specialist rating. The highest correlation coefficient was between the specialist’s rating and ACT score.

ACT scores differed across groups of patients according to level of asthma control as defined by either specialist rating or predicted FEV1 values; the higher the score, the better the asthma control. Additionally, ACT scores were significantly lower in patients who needed additional treatment than in those whose therapy was decreased or unchanged.

One item in ACT that the authors found particularly significant was the impact of asthma on patients’ daily functioning at work or school. This variable had a strong ability to discriminate between those with or without asthma control, which suggests that functional impairment is something that clinicians should routinely assess. Another useful item in ACT was the patient’s self-assessment of asthma control, which—despite the findings of previous studies—had a high degree of concordance with the specialists’ ratings.

Nathan RA, Sorkness CA, Kosinski M, et al. Development of the Asthma Control Test: a survey for assessing asthma control. J Allergy Clin Immunol. 2004;113:59-65.

DOG OWNERSHIP MAY PREVENT ATOPY IN INFANTS

The question of whether pet ownership influences the development of atopy in children has never been definitively answered. Gern et al reviewed data from the Childhood Origins of Asthma (COAST) study to determine what effect pet ownership had on various markers of atopy during the first year of life. They found that dog ownership was associated with a reduced incidence of atopic dermatitis and increased secretion of interleukin (IL)-10 and IL-13.

All infants had at least one parent with allergic rhinitis, asthma, or both. Home environments were assessed via questionnaires that included specific queries about pet ownership. Physical examinations were performed at ages 2, 4, 6, 9, and 12 months. The incidence of atopic dermatitis was recorded for each child.

Of 285 infants, 68 were exposed to dogs, 51 were exposed to cats, 33 were exposed to both, and 133 had no pets in the home. The incidence of atopic dermatitis and positive skin tests was reduced in the infants exposed to dogs alone, or to dogs and cats, but not to cats alone.

Dog exposure was associated with a 48% increase in IL-10 and a 24% rise in IL-13, compared to no dog exposure. Thus, postnatal exposure to dogs appears to alter immune development and reduce allergic sensitization in the first year of life. The authors speculated that exposure to dogs stimulates the immune response, thereby increasing mononuclear cells and IL-10—which could be responsible for preventing allergic sensitization.

Gern JE, Reardon CL, Hoffjan S, et al. Effects of dog ownership and genotype on immune development and atopy in infancy. J Allergy Clin Immunol. 2004;113:307-314.

SAFE, CONVENIENT TREATMENT OF NONMASSIVE PULMONARY EMBOLISM

A meta-analysis recently conducted by Quinlan et al indicates that low-molecular-weight heparin (LMWH) is as effective as intravenous unfractionated heparin for the treatment of nonmassive pulmonary embolism.

The study included randomized controlled trials comparing LMWH with dose-adjusted unfractionated heparin for pulmonary embolism—either symptomatic or asymptomatic. The primary outcome was recurrent venous thromboembolism at the end of the treatment period.

Twelve studies were identified from MEDLINE, EMBASE, and the Cochrane Library. Clinical outcomes in these studies were recurrence of symptomatic venous thromboembolism, major bleeding, minor bleeding, and death.

Six studies included patients with symptomatic pulmonary thromboembolism, two included patients with symptomatic deep venous thrombosis who were screened for pulmonary thromboembolism, and four included patients with symptomatic deep venous thrombosis or pulmonary embolism. Treatment was continued for a mean of five to 14 days. Patients were followed up for at least three months in all studies but one.

There were no significant differences between treatment groups in the incidence of symptomatic venous thromboembolism at the end of treatment or at three months, nor was there any difference in all-cause mortality. All LMWH preparations had roughly the same safety and efficacy.

This meta-analysis supports the use of LMWH as first-line treatment for nonmassive pulmonary embolism.

Quinlan DJ, McQuillan A, Eikelboom JW. Low-molecular-weight heparin compared with intravenous unfractionated heparin for treatment of pulmonary embolism: a meta-analysis of randomized, controlled trials. Ann Intern Med. 2004;140:175-183.

WHAT PREDICTS RELAPSE AFTER COPD EXACERBATION?

In the United States, more than one million COPD exacerbations are treated on an outpatient basis in the emergency department (ED) each year. Kim et al conducted a multicenter prospective study and found that several historical factors can predict relapse risk and that these factors can be identified during a COPD-related ED visit.

Data were taken from two prospective cohort studies and included patients with a physician diagnosis of COPD who were treated in an ED and sent home. Two weeks after the ED visit, patients took part in a telephone interview that asked about any urgent COPD-related visits, changes in medical management, use of medications, frequency of moderate-to-severe COPD exacerbations during the previous 12 months, subjective symptom severity, activity limitations, and quality of life.

Of the 140 patients included in the study, 30 reported a COPD exacerbation relapse within two weeks of their original ED visit. Although half of patients reported concomitant asthma, its presence was not related to relapse rate. Quality of life was uniformly poor but also had no relationship to relapse rate.

The significant factors associated with relapse were urgent care or ED visits in the previous year, self-reported activity limitations in the past 24 hours, and respiratory rate at ED presentation.

A significant number of patients treated for COPD exacerbations have relapses within two weeks. The authors noted that this figure has remained essentially unchanged since the 1980s.

Kim S, Emerman CL, Cydulka RK, et al. Prospective multicenter study of relapse following emergency department treatment of COPD exacerbation. Chest. 2004;125:473-481.

EXHALED NITRIC OXIDE FOR ASTHMA DIAGNOSIS

Measuring peak expiratory flow or response to a bronchodilator or oral corticosteroid is the current standard for diagnosing asthma. Yet, both these tests have low sensitivity and may not accurately diagnose patients with less severe asthma. Smith and colleagues evaluated the ability of exhaled nitric oxide and induced sputum analysis to accurately diagnose asthma in 47 consecutive patients.

Patients were evaluated three times at two-week intervals. They completed a symptom questionnaire, and between the second and third visits, they were given a 14-day trial of oral prednisone. All patients underwent standard pulmonary function testing. At the final visit, asthma was diagnosed based on relevant patient history and a positive test for bronchial hyperresponsiveness and/or a positive response to a bronchodilator. Exhaled nitric oxide was measured before any forced expiratory maneuvers. Sputum was also collected for cell analysis.

Of the 47 patients, 17 were diagnosed with asthma. Compared with the nonasthmatic group, those with asthma had a significantly lower FEV1 and FEV1/FVC ratio. In contrast, exhaled nitric oxide and sputum eosinophil levels were significantly higher in these patients than in the nonasthmatic group. Both exhaled nitric oxide and sputum eosinophils were significantly more accurate for asthma diagnosis than were tests based on lung function.

Measuring exhaled nitric oxide is a simple, noninvasive diagnostic method that can be easily performed as part of routine pulmonary function testing, the authors asserted. Thus, they believe it to be superior to induced sputum analysis, even though that test is almost as accurate as nitric oxide measurements.

Smith AD, Cowan JO, Filsell S, et al. Diagnosing asthma: comparisons between exhaled nitric oxide measurements and conventional tests. Am J Respir Crit Care Med. 2004;169:473-478.

WHAT DOES ELEVATED DLCO MEAN?

Although the clinical implications of a low diffusing capacity of the lung for carbon monoxide (DLCO) are well known, the significance of a high DLCO is less certain. A study by Saydain et al compared patients with high versus low DLCO and found that obesity, asthma, and large lung volumes were more common among those with high DLCO.

The population included 245 patients with high DLCO (greater than 140% of predicted) who were each matched with a control patient who had DLCO values between 85% and 115% of predicted. All medical records were reviewed, and age, sex, height, weight, smoking history, clinical diagnoses, and pulmonary function test results were recorded.

Compared with controls, patients with high DLCO had a higher mean body weight and body mass index. Lung function test parameters also differed between the groups. Obesity and asthma were more common in the high-DLCO group; 62.4% of the high-DLCO patients, but only about half that many in the control group, had a diagnosis of asthma, obesity, or both.

The authors noted that in patients with high DLCO, diseases known to lower DLCO may reduce DLCO to normal levels and, hence, go undetected. In these patients, they wrote, it may be better to measure change in DLCO over time and to monitor alterations in gas exchange.

Saydain G, Beck KC, Decker PA, et al. Clinical significance of elevated diffusing capacity. Chest. 2004;125:446-452.

CORTICOSTEROIDS KEY IN TREATING OTITIS EXTERNA

What types of ear drops are best for acute otitis externa? A recent study by van Balen et al found that corticosteroids enhanced the efficacy of both antibiotics and acetic acid and thus should be a component of any ear drops selected for treatment.

Patients were assigned to receive one of three therapies: acetic acid (n = 71), acetic acid plus a corticosteroid (n = 63), or a corticosteroid plus an antibiotic (n = 79). All groups were given three ear drops three times per day. Patients were followed up at seven, 14, and 21 days. After 42 days, patients were contacted and asked whether their symptoms had recurred.

Median time to recovery was eight days in the acetic acid group, seven days in the corticosteroid/acetic acid group, and six days in the corticosteroid/antibiotic group. The overall cure rates at seven, 14, and 21 days, respectively, were 40%, 72%, and 79%. However, the recovery rates in the acetic acid group at days 14 and 21 were significantly lower than those in the other groups.

The corticosteroid/acetic acid and corticosteroid/antibiotic combinations produced similarly high recovery rates; no differences between them were seen.

Fifty patients had a recurrence of symptoms between 21 and 42 days, with higher recurrence rates and symptom severity in the acetic acid group. The authors concluded that a combination of a corticosteroid and an antibiotic or acetic acid is more effective than acetic acid alone in resolving symptoms of otitis externa.

van Balen FAM, Smit WM, Zuithoff NPA, Verheij TJM. Clinical efficacy of three common treatments in acute otitis externa in primary care: randomised controlled trial. BMJ. 2003;327:1201-1203.

FOR VAP, EIGHT DAYS OF ANTIBIOTICS ARE ENOUGH

Traditionally, 14 to 21 days of antibiotic therapy has been used to treat ventilator-associated pneumonia (VAP). Although there is little evidence to support this prolonged duration of therapy, the high rate of relapse in VAP has seemed to justify it. But new evidence argues for a shorter treatment period. In a randomized trial Chastre et al have shown that an eight-day antibiotic regimen is as effective as a 15-day regimen in ICU patients with VAP.

A total of 401 ICU patients who were intubated and had received mechanical ventilation for at least 48 hours were included in the study. All patients had clinical suspicion of VAP confirmed by bronchoscopy. Patients were assigned to receive antibiotics either for eight days or 15 days. Drug selection was left to the physician, including any treatment changes after the pathogen was identified. The primary outcomes included death from any cause, recurrence of infection, and number of antibiotic-free days.

By 28 days after onset of VAP, 37 (19%) of the 197 patients given eight days of treatment had died, compared with 35 (17%) of the 204 patients who received the 15-day regimen. The recurrence rate was also similar in the two groups. However, the patients in the eight-day group had significantly more antibiotic-free days and significantly more days free from broad-spectrum antibiotics than did those in the 15-day group.

The authors concluded that there was no benefit to treating patients for VAP beyond eight days.

Chastre J, Wolff M, Fagon JY, et al. Comparison of 8 vs 15 days of antibiotic therapy for ventilator-associated pneumonia in adults: a randomized trial. JAMA. 2003;290:2588-2598.

Return to table of contents