RESPIRATORY ILLNESS AFFECTS FLOW RATES IN CHILDREN

Respiratory illness in children reduces expiratory flow rates, and children with active asthma or hay fever are affected to a greater degree than those without. Rappaport and colleagues studied pulmonary function variability in relation to self-reported respiratory illness, asthma, and hay fever among 1,103 children (ages 9 to 20 years) from the Children’s Health Study.

Pulmonary function testing was performed twice on each child within a four-month period. Respiratory illness was self-reported, as was the presence of asthma or hay fever. Children were grouped, according to their health status at the first and second tests, as well-well, sick-well, or well-sick.

A significant loss in performance was observed in the well-sick group for forced expiratory volume in one second (FEV1), peak expiratory flow rate, forced expiratory flow between 25% and 75% of vital capacity (FEF25-75), and forced expiratory flow at 75% of vital capacity (FEF75).

Active asthma increased the impact of respiratory illness on FEV1, FEF25-75, and FEF75 (Table 1). These effects were magnified in the asthmatic children with persistent wheeze or cough. Hay fever also increased the impact of respiratory illness on pulmonary function. However, its effects were greater in the children with both hay fever and asthma than in those with only hay fever.

Rappaport EB, Gilliland FD, Linn WS, Gauderman WJ. Impact of respiratory illness on expiratory flow rates in normal, asthmatic, and allergic children. Pediatr Pulmonol. 2002;34:112-121.

 

Table 1 Changes in Pulmonary Function Resulting From Respiratory Illness
	Percent change
Children (ages 9 to 20 years) with:	FEV1	PEFR	FEF25–75	FEF75
No asthma	–1.2	–0.7	2.0	1.8
Asthma	–3.1*	–3.5	–9.7*	–10.0*
Without persistent wheeze   or cough	–1.4	–0.9	0.3	0.3
With persistent wheeze    or cough	–4.8*	–7.1	–17.8*	–22.0*
No hay fever	–0.4	–1.8	–1.9	–2.9
Hay fever	–3.0*	–2.6	–10.8*	–17.5*
Without asthma	–2.5	–3.0	–6.8	–13.4
With asthma†	–4.2	–1.8	–18.4	–25.5
* Difference from previous test is significant. † No direct comparison was made between changes in the children with both hay fever and asthma and changes in those with only hay fever. FEV1, forced expiratory volume in one second; PEFR, peak expiratory flow rate; FEF25–75, flow between 25% and 75% of vital capacity; FEF75, forced expiratory flow at 75% of vital capacity. Data extracted from Rappaport et al. Pediatr Pulmonol. 2002.

SMOKING CESSATION DRUG HELPS AFRICAN-AMERICANS

Slow-release bupropion is effective for smoking cessation in African-Americans, according to a randomized, placebo-controlled study by Ahluwalia et al. This finding is particularly important given that African-Americans have lower quitting success rates than white Americans do—despite the fact that they are more likely to attempt to quit smoking.

Six hundred African-American smokers randomly received either bupropion or placebo for seven weeks. The bupropion dosage initially was 150 mg once per day; after three days, it was increased to 150 mg twice daily. Both groups received eight counseling sessions and a smoking cessation guide. Participants had follow-up visits at weeks 1, 3, and 6 and at three, five, and six months.

The cessation rate in the treatment group was significantly better than that in the placebo group (36.0% vs 19.0%) at the end of seven weeks, and the difference was maintained for 26 weeks (21.0% vs 13.7%). The treatment group also had a significantly greater mean reduction in depressive symptoms than did the placebo group. However, bupropion had no effect on withdrawal symptoms. The investigators recommended that smoking cessation medications such as bupropion be covered by health insurance programs.

Ahluwalia JS, Harris KJ, Catley D, et al. Sustained-release bupropion for smoking cessation in African Americans: a randomized controlled trial. JAMA. 2002;288:468-474.

BREAST-FEEDING MAY PROTECT AGAINST ASTHMA

Studies of whether breast-feeding by asthmatic mothers increases their children’s risk of asthma have produced conflicting results. Oddy and colleagues used data from the Western Australia Pregnancy Cohort to examine the relationship between maternal asthma status, duration of breast-feeding, and risk of childhood asthma. They found that exclusive breast-feeding for four months or more resulted in lower rates of asthma in children of asthmatic mothers.

As part of the study, mothers recorded illnesses, feeding history, and other events in the first year of the child’s life. At six-year follow-up, 2,602 children were tested for current asthma and atopy. Maternal asthma status was also determined at this time.

Seventeen percent of the children and 15% of the mothers were found to have asthma at follow-up. Maternal asthma, child’s atopic status, and exclusive breast-feeding for less than four months were all significantly related to current asthma in the child. However, exclusive breast-feeding for a longer duration was protective against asthma, even for the children of mothers with the disease.

The researchers found no evidence that the child’s atopic status or maternal asthma status altered the protective effect of exclusive breast-feeding in infancy. They recommend that infants be exclusively breast-fed for at least four months.

Oddy WH, Peat JK, de Klerk NH. Maternal asthma, infant feeding, and the risk of asthma in childhood. J Allergy Clin Immunol. 2002;110:65-67.

COMPLICATED PNEUMONIA INCREASING IN CHILDREN

The frequency of complicated pneumococcal pneumonia in children is increasing, a multicenter study has found. Tan and colleagues reported on the findings of the United States Pediatric Multicenter Pneumococcal Surveillance Study Group. Children hospitalized with pneumonia attributed to Streptococcus pneumoniae between September 1, 1993, and January 1, 2000, were retrospectively identified. Isolates underwent serotyping and antimicrobial susceptibility tests.

The study included 368 children with pneumococcal pneumonia, 133 of whom had complicated pneumonia. The proportion of children with complicated pneumonia increased steadily during the study period, from 22.6% in 1994 to 53% in 1999. Patients with complicated pneumonia were older (mean age, 45 months) and significantly more likely to be of white race and to have chest pain on presentation.

Serotype 1 caused a markedly larger percentage of complicated infections (24.4%) than of uncomplicated infections (3.6%). Serotype 3 caused 8.4% of complicated infections and 2.7% of uncomplicated infections. No difference in the rate of resistant organisms was seen between the two types of infection.

The reasons for the increase in frequency of complicated pneumonia are not known. The investigators note that 56% of complicated infections and 77% of uncomplicated infections had serotypes included in the currently licensed pneumococcal vaccine.

Tan TQ, Mason EO Jr, Wald ER, et al. Clinical characteristics of children with complicated pneumonia caused by Streptococcus pneumoniae. Pediatrics. 2002;110:1-6.

PROBIOTICS FOR DIARRHEA PREVENTION

Probiotics (live microbial supplements) may help prevent antibiotic-associated diarrhea. D’Souza et al reached this conclusion after performing a meta-analysis of studies comparing probiotics with placebo for treatment of diarrhea during antibiotic therapy.

Nine double-blind, placebo-controlled trials were identified from a literature search. Four trials used Saccharomyces boulardii (yeast), four used lactobacilli, and one used a strain of enterococcus that produces lactic acid. Both yeast and non-yeast trials showed more favorable results with active treatment than with placebo. Six studies showed a significant benefit with probiotic treatment.

The investigators concluded that probiotics may be effective in preventing antibiotic-associated diarrhea. They acknowledged that their analysis included only a small number of studies and that between-trial differences in dose and duration of both probiotic and antibiotic treatments may account for discrepancies in trial results.

D’Souza AL, Rajkumar C, Cooke J, Bulpitt CJ. Probiotics in prevention of antibiotic associated diarrhoea: meta-analysis. BMJ. 2002;324:1361-1364.

PREDICTING SURVIVAL IN PPH

In primary pulmonary hypertension (PPH), peak oxygen uptake (VO2) and systolic blood pressure are the strongest predictors of survival, a new study has revealed.

Wensel et al set out to determine the prognostic value of many factors in PPH. In addition to traditional markers, two variables—VO2 and the slope of the linear regression of ventilation to carbon dioxide production during exercise (VE/VCO2 slope)—were included because they are powerful predictors in chronic heart failure. Serum uric acid levels were measured because they correlate with both exercise capacity and PPH severity.

Eighty-six patients with PPH were recruited. Exercise testing was performed in all but 16 patients, during which blood pressure, VO2, and VE/VCO2 slope were measured. All patients also underwent right heart catheterization. During a mean 1.5-year follow-up, 28 patients died and 16 underwent double-lung transplantation.

Multivariate analysis showed that peak systolic blood pressure, serum uric acid levels, peak VO2, and peak diastolic blood pressure were independent predictors of outcome. Further analysis showed that peak systolic blood pressure and peak VO2 during exercise were highly accurate predictors of one-year survival.

Likewise, Kaplan-Meier survival analysis showed that patients with a peak systolic blood pressure above 120 mm Hg had a significantly better prognosis at one year, as did patients with a peak VO2 above 10.4 mL·kg–1·min–1. The investigators noted that resting hemodynamic data did have prognostic value, but the data added no information to that obtained from peak VO2 and systolic blood pressure.

Wensel R, Opitz CF, Anker SD, et al. Assessment of survival in patients with primary pulmonary hypertension: importance of cardiopulmonary exercise testing. Circulation. 2002;106:319-324.

—Mimi Zucker, PhD