International trends in asthma mortality: 1970 to 1985.

Recent international trends in asthma mortality among people aged five to 34 years were examined as a follow-up to an epidemic of asthma deaths in the late 1970s which appeared to be confined to New Zealand. Mortality rates were compared in 14 countries with suitable statistics; Australia, Canada, England and Wales, Finland, France, Japan, Israel, the Netherlands, New Zealand, Singapore, Sweden, Switzerland, the United States, and West Germany, for the period 1970 to 1984/5. In New Zealand, asthma mortality in this age group more than trebled from 1.3 per 100,000 in 1974 to 4.2 per 100,000 in 1979 and since then has declined substantially to 1.85 per 100,000 in 1985. Asthma death rates vary more than six-fold among the other countries examined, and although the New Zealand experience has not been seen to the same degree elsewhere, a gradual increase in reported asthma mortality has occurred since the mid to late 1970s in the majority of countries studied. The increase and subsequent decline in asthma mortality in New Zealand could not be explained by changes in diagnostic fashions or in the International Classification of Disease coding rules. Similarly, the US data do not suggest there is diagnostic transfer among diseases of airway obstruction. However, part of the differences in asthma mortality among the countries examined and the recent increases in asthma death rates, could be due to changing diagnostic fashions rather than true differences in mortality. International studies on the validity of asthma death statistics and on asthma prevalence are required to clarify these issues.

Accuracy of computed tomographic scanning in assessment of the mediastinum in bronchial carcinoma.

We believe that malignant involvement of mediastinum is a contraindication to attempted resection of bronchial carcinoma. It was hoped that computed tomographic (CT) scanning might improve our ability to assess the mediastinum prior to thoracotomy. The accuracy of CT scanning, performed with modern techniques, in assessment of the mediastinum of 22 patients with bronchial carcinoma has therefore been determined. In all the patients CT scan impressions have been correlated with the histologic findings at thoracotomy or mediastinoscopy. In detection of malignant involvement of the mediastinum, the CT scan had a sensitivity of 80% and a specificity of 76%. There was only one false negative CT scan report, and in this case the mediastinum was involved at a site which could not have been inspected at anterior cervical mediastinoscopy. We conclude that a negative CT scan makes mediastinoscopy an unnecessary screening procedure in determining resectability. Since there was a significant number of false positive CT scans, we feel that such a report necessitates tissue confirmation before the decision to withhold thoracotomy is made. The CT scan may help to determine the best test to achieve this tissue confirmation.

The association between asthma drugs and severe life-threatening attacks.

OBJECTIVES: To measure the association between asthma drugs and death or ICU admission due to asthma (severe life-threatening attack of asthma [SLTA]), and to assess the possibility that these associations may not be causal but due to the prescription of these drugs to patients with more severe disease (confounding). DESIGN: Retrospective cohort study of 655 asthmatics who attended an emergency department in 1986 to 1987 followed till death or May 1989. METHODS: Outcome events were death or ICU admission due to asthma (SLTA). All hospital attendances were identified and patients classified at each according to drug exposure and a wide variety of measures of asthma severity. Incidence rates were computed as total outcome events divided by person-time contributed for each subject classified according to drug use and asthma severity. Rate ratio (RR) estimates for severe asthma outcomes associated with use as compared to nonuse of asthma drugs were calculated. Severity markers were identified and used to adjust the crude RR estimates. RESULTS: One hundred five SLTAs (15 deaths, 90 ICU admissions) occurred in 66 patients. Like inhaled fenoterol, oral beta-agonists, theophylline, cromolyn, inhaled steroids, and oral steroids were all associated with an increased risk of SLTA. When adjusted progressively for measures of severity, these increased risks became insignificant except for cromolyn. CONCLUSION: Unadjusted RR estimates for severe asthma events comparing exposure to a particular drug with nonuse are overestimates due to confounding. Control with two severity markers (hospital admission in the last year, use of oral corticosteroid at the time of previous admission) removes some confounding but control for additional severity markers not available in previous studies reduces the effect estimates further. These results suggest that the problem of confounding is substantial in nonrandomized epidemiologic studies of asthma drugs. Previous studies reporting RR estimates are likely to be confounded.

The effects of cardiopulmonary bypass upon pulmonary gas exchange.

Cardiac output, venous admixture, physiological dead space, blood gas tensions, inspired gas distribution, and other respiratory variables were measured in 10 patients breathing both air and oxygen before and on five occasions up to 10 days after coronary artery vein-graft operations under cardiopulmonary bypass with moderate hypothermia. Cardiac output was unchanged at 8 hours but fell 8 percent by 22 hours. Thereafter it progressively increased and at 10 days was higher than before the operation. Venous admixture rose to a maximum at 28 to 48 hours, postoperatively, but the increase was inversely related to the magnitude of preoperative admixture. The part played by airway and alveolar closure in determining venous admixture is discussed. While admixture increased, the nitrogen-clearance curve improved, presumably due to progressive "dropout" of the worst-ventilated regions. Physiological dead space fell to a minimum at 28 hours after operation; this was attributed to a fall in the end-inspiratory position consequent upon a reduction in both functional residual capacity and tidal volume. There was an increase in ventilation after operation, and this persisted at 10 days; it appeared to be due to reflex stimulation from the lungs and chest wall.

Spirometry in primary care practice: the importance of quality assurance and the impact of spirometry workshops.

OBJECTIVE: To determine the quality of spirometry performed in primary care practice and to assess the impact of formal training. DESIGN: Randomized, controlled prospective interventional study. SETTING: Primary care practice, Auckland City, New Zealand. PARTICIPANTS: Thirty randomly selected primary care practices randomized to "trained" or "usual" groups. One doctor and one practice nurse were nominated to participate from each practice. INTERVENTIONS: "Trained" was defined as participation in an "initial" spirometry workshop at week 0 and a "maintenance of standards" workshop at week 12. "Usual" was defined as no formal training until week 12, when participants they attended the same "initial" workshop provided for the trained group. The study duration was 16 weeks. Each practice was provided with a spirometer to be used at their clinical discretion. MEASUREMENTS AND RESULTS: Spirometry data were uploaded weekly and analyzed using American Thoracic Society (ATS) criteria for acceptability and reproducibility. The workshops were assessed objectively with practical and written assessments, confirming a significant training effect. However, analysis of spirometry performed in clinical practice by the trained practitioners revealed three acceptable blows in only 18.9% of patient tests. In comparison, 5.1% of patient tests performed by the usual practitioners had three acceptable blows (p<0.0001). Only 13.5% of patient tests in the trained group and 3.4% in the usual group (p<0.0001) satisfied full acceptability and reproducibility criteria. However, 33.1% and 12.5% of patient tests in the trained and usual groups, respectively (p<0.0001), achieved at least two acceptable blows, the minimum requirement. Nonacceptability was largely ascribable to failure to satisfy end-of-test criteria; a blow of at least 6 s. Visual inspection of the results of these blows as registered on the spirometer for the presence of a plateau on the volume-time curve suggests that < 15% were acceptable. CONCLUSIONS: Although a significant training effect was demonstrated, the quality of the spirometry performed in clinical practice did not generally satisfy full ATS criteria for acceptability and reproducibility. Further study would be required to determine the clinical impact. However, the ATS guidelines allow for the use of data from unacceptable or nonreproducible maneuvers at the discretion of the interpreter. Since most of the failures were end-of-test related, the FEV1 levels are likely to be valid. Our results serve to emphasize the importance of effective training and quality assurance programs to the provision of successful spirometry in primary care practice.

Socioeconomic status in childhood asthma.

This study examines the relationship between socioeconomic status (SES) and asthma prevalence and the use of asthma medication. One thousand and fifty European children aged eight and nine years were studied by parent completed questionnaire and histamine inhalation challenge. After controlling for sex of the child and for smokers in the house there were significantly higher lifetime (P = 0.029) and current (P = 0.046) prevalence rates of wheeze in children in low SES groups. There was no relationship between SES and asthma diagnosis, bronchial hyperresponsiveness (BHR: PD20 less than 7.8 mumol), or any combination of BHR with symptoms or diagnosis. The use of bronchodilators and asthma prophylactic drugs was less frequent in the low SES groups of children with wheeze in the last 12 months both with concurrent BHR or irrespective of BHR than in those in high SES groups.

A tool for measuring the asthma self-management competency of families.

A tool for measuring a family's asthma self-management behaviour has been developed for a study examining the relationships of asthma self-management behaviour, knowledge, and psychosocial factors with various indices of morbidity in children with asthma. The tool involves a structured interview which includes three typical situations of asthma self-management (scenarios). Each of the scenarios is divided into graded challenges. A scoring schedule was developed according to the critical incidents of self-management inherent in each situation. This schedule was then applied to the verbatim transcripts of the subjects' responses. These were presented to 380 asthmatic children aged 5-11 yr and their primary caregivers. Inter-rater reliability, inter-rater agreement and test-retest reliability coefficients indicate that the scores obtained are stable across raters and time. Correlations between scores on different scenarios suggest there is a common factor of self-management competency across all scenarios, but families are better at some aspects of self-management than others. The distribution of scores for each scenario is presented. The place of this tool as a means of assessing self-management behaviour is discussed.

Human pulmonary dirofilariasis.

Dirofilaria immitis, the canine heartworm, is a relatively rare, but well-documented cause of human lung disease. The disease presents in man as a solitary, peripheral parenchymal lung nodule which may simulate a peripheral lung neoplasm. This case is the first report of the disease in New Zealand, a country where the parasite has not become established in the dog population. A brief review of the life cycle, epidemiology and clinical data relating to human dirofilariasis is included.

Death from asthma in Auckland: circumstances and validation of causes.

New Zealand has experienced an epidemic of asthma deaths since 1977 with mortality rates of over 3.0/100 000 for people aged 5-34 years, more than three times the rate of comparable countries. To examine the reasons for this high mortality rate all deaths from asthma in people under 70 years in the Auckland region in 1981-82 were investigated. A total of 84 possible cases were studied and the validity of death certificates was found to be excellent for people under the age of 50 years. Fifty-three cases had usefully reversible asthma at the time of death and the mortality rate was almost four times higher in Pacific Islanders than in caucasians, with the Maori rate being intermediate. Sixty-seven percent (35) of the deaths in people with usefully reversible asthma occurred at home. In only 40% of cases had the patient reached some form of medical care. No deaths occurred in the patients admitted to hospital with the diagnosis of asthma during this period.

Lessons from the national asthma mortality study: deaths in hospital.

The circumstances surrounding 38 deaths from asthma in hospital in New Zealanders under 70 years of age between August 1981 and July 1983 have been analysed. Twelve deaths did not appear to be preventable, all but one occurring in chronic severe asthmatics despite apparently optimal therapy. Critical delays by patients or relatives in seeking medical help occurred in six cases, and inadequate assessment of severity and undertreatment by medical practitioners prior to the patient reaching hospital was a major contributing factor in a further six deaths. In four cases, insufficient speed and indecisive treatment in the accident and emergency department appeared to contribute to death. Ten patients died after many hours or days in hospital wards in circumstances where assessment, monitoring and treatment were deficient. There were no deaths in intensive care units. Urgent expert assessment is necessary in A & E departments, and more severe cases should be managed in intensive care units. Patients with acute severe asthma may need continuous oxygen, intravenous therapy and close objective assessment for a week or more after hospitalisation.

Effects of a physical conditioning programme on asthmatic patients.

AIMS: to determine whether moderate/severe asthmatics can improve their physical fitness using standard commercial gymnasium fitness programmes and to examine the effect on their asthma. METHODS: eight moderate to severe asthmatics and seven nonasthmatic controls were tested before and after 12 weeks indoor circuit training at a commercial gymnasium. The aerobic fitness of both groups was assessed before, during and after the conditioning period. Measures of asthma severity, habitual activity levels and psychological status were also assessed. RESULTS: peak oxygen uptakes increased significantly in both asthmatics and controls, mean and 95% confidence interval (95% CI) values rising from 27.5 (21.9-33.0) to 31.3 (23.5-39.1) and 29.2 (25.9-32.5) to 32.2 (28.5-35.9) mL.min-1.kg-1 respectively. Following training, minute ventilation at high workloads was significantly reduced in the asthmatic subjects. In all participants subjective ratings of the ability to perform physical tasks was significantly increased as was the amount of habitual physical activity reported. Although the asthmatics' bronchial responsiveness to histamine, medication usage and symptom scores did not change, the daily recorded peak expiratory flow (PEFR) increased slightly, and its variability declined. CONCLUSIONS: these findings demonstrate that with proper management severe asthmatics can engage in vigorous circuit training and enjoy the health benefits of regular exercise.

Measuring morbidity from asthma in children.

AIMS: To develop new measures of asthma morbidity which would be applicable to children with asthma of all grades of severity. METHODS: This study used a cross sectional sample of asthmatic children. Traditional asthma morbidity measures (admission to hospital, use of Emergency Room, general practitioner, after hours deputising service and ambulance) were compared with new measures (school attendance, teacher assessment, parental perception of morbidity and parents emotional response to child's asthma). RESULTS: Data was obtained for 381 children with asthma. Children with poor school attendance were found in the severe group as judged by a composite score using traditional measures (r = 0.30, p < 0.0001). A new composite morbidity score based on two questions about parental perception of severity (how often has asthma prevented participation in activities and rating of severity of asthma in general over the last year) and two questions about parent emotional response to the child's asthma (how often has your child's asthma (a) made you feel frightened and (b) stopped family activities) was developed. This new measure of asthma morbidity was correlated with the composite score using traditional morbidity measures (r = 0.43, p < 0.0001) and with school attendance (r = 0.28, p < 0.0001). CONCLUSION: These new morbidity measures are quick and easy to use, and provide an opportunity to measure asthma severity at the moderate to mild end of the severity spectrum. We recommend their use for both clinical assessment and research.

Asthma mortality in New Zealand: a two year national study.

The epidemic of deaths from bronchial asthma in New Zealand was investigated by a two-year national review of all deaths of persons under 70 years where "asthma" appeared in part I of a death certificate or in a coroner's report of cause of death. Information about the patients, the characteristics and management of their asthma and the circumstances of the fatal episode was obtained by interviewing relatives and general practitioners and perusal of hospital records. The reviewing panel of the asthma task force of the Medical Research Council considered 271 of the 342 deaths studied were due to asthma. A high national asthma mortality rate (5.1 per 100 000) was confirmed, with rates for Maoris (18.9) and Pacific Islanders (9.4) considerably higher than that for Europeans (3.4 per 100 000). After standardising for age and ethnic groups, there remained a threefold variation in mortality rates among health districts suggesting regional differences in prevalence, severity or management of asthma. No single cause for these high mortality rates was found. One-quarter of the deaths occurred in patients who had had previous life threatening attacks. Excessive use of bronchodilator drugs did not account for the high mortality rates, but inappropriate prolonged use of a home nebuliser may have delayed institution of other therapy in a few cases.

Lessons from the national asthma mortality study: circumstances surrounding death.

The circumstances surrounding all deaths from asthma in New Zealanders under 70 years of age between August 1981 and July 1983 have been analysed from information recorded or recalled by doctors or relatives of the deceased. Factors which may have reduced the time available for effective treatment of these severe attacks are described to draw attention to ways in which mortality might be reduced. For almost half of the 271 deaths medical help had not been called before the patient was in extremis. When medical help was summoned in sufficient time doctors commonly did not give corticosteroids or used them inadequately. Difficulties in using medical care and noncompliance with asthma management were common particularly in Polynesian patients. In 38% of patients some medical inadequacy appeared to contribute to poor long-term care and education. Failure of patients to attend for ongoing medical care, education and preventative treatment, or a medical failure to deliver these may have led to chronically reduced lung function. Any further deterioration may then have more rapidly led to a fatal outcome. Lack of patient or family awareness about how to detect and cope with an unusually severe attack was found and contributed to avoidable fatalities.