Monitoring performance in the NHS. The district neural tube defect screening service.

A small medical school team has developed a six item system (SIS) for monitoring the neural tube defect (NTD) screening service. SIS is discussed in relation to possible alternative monitoring systems and the advantages which led to its implementation are described. In July 1982 the system was introduced in three districts in South Wales and the first year's results are presented. These permit the local provision, written policies and clinical and management responsibility of the service to be examined and deficiencies in the relevant information systems to be identified. Of particular concern is the discovery that districts have no way of knowing the number of terminations for NTD, and thus their current NTD incidence. In view of these findings, it would seem advisable for all districts providing NTD screening to monitor their service. SIS provides a simple, cheap and effective monitoring system which could be easily implemented throughout England and Wales.

Epidemiological study of Pasteurella multocida and Bordetella bronchiseptica in atrophic rhinitis.

An epidemiological study of atrophic rhinitis was carried out in four pig herds. Observations were made of (i) infection with Bordetella bronchiseptica and Pasteurella multocida, (ii) the presence of brachygnathia superior (BS score), (iii) the extent (grade) of turbinate atrophy and pneumonia at slaughter and (iv) growth rates from two to 16 weeks of age and average daily weight gains to slaughter. In two of the herds with no history of atrophic rhinitis, B bronchiseptica and non-toxigenic strains of P multocida were isolated; only one of 47 pigs (2 per cent) had a BS score greater than +10 mm and the most severe turbinate atrophy observed in 21 pigs at slaughter was grade 3. In contrast, from two herds with atrophic rhinitis, toxigenic strains of P multocida were isolated as well as B bronchiseptica and non-toxigenic P multocida. BS scores of greater than +10 mm were present in six of 47 pigs (13 per cent) of which five were infected with toxigenic P multocida and had severe turbinate atrophy of grade 4 or 5. There was no significant reduction in growth rates in the affected compared with the unaffected herds nor in the affected compared with the unaffected pigs in the same herd. Neither was there a correlation between progressive disease and the extent of pneumonia found at slaughter. It was concluded that in field cases of the disease, high BS scores plus severe turbinate atrophy were associated with infection by toxigenic type-D strains of P multocida.

Epidemiology in anaesthesia: a method for predicting hospital mortality.

Data on 13 043 operations were abstracted from 108 878 anaesthetic records in the Cardiff Anaesthetic Record System. Nine groups of surgical operations with high mortality in hospital were identified. These records were analysed using a logistic regression model to determine the probability of death in hospital. Variables included in the model were age, sex, elective or emergency operation and five intercurrent diseases. The significance of individual variables was assessed: age was the most important single variable in six of the nine operation groups. The model was used to calculate the risk of death in hospital for individuals with specific characteristics. With further development, this technique might be used by clinicians at other centres to predict the outcome for patients under their care.

Diagnostic effectiveness of ultrasound in detection of neural tube defect. The South Wales experience of 2509 scans (1977-1982) in high-risk mothers.

2509 pregnant women were investigated between April 1, 1977, and March 31, 1980 (study 1), and April 1, 1980, and March 31, 1983 (study 2), to assess the effectiveness of diagnostic ultrasound in the diagnosis of neural tube defect (NTD) in women judged to be at high risk of NTD on the basis of raised serum alpha-fetoprotein or family history, or of other congenital malformation. The detection rate (sensitivity) for anencephaly was 100% in both studies. The detection rate for open spina bifida (OSB) improved from 33% in study 1 to 80% in study 2, specificity rose from 96% to 99%, the false-positive rate dropped from 57% to 9%, and the false-negative rate fell from 1% to 0.3%. Diagnostic ultrasound is likely to be conducted with greater vigilance and subjected to greater scrutiny than routine ultrasound because the patients have already been selected as being at high risk, the operators are more experienced, and their apparatus is likely to be more refined than that used for routine ultrasound. It is unlikely that the effectiveness levels for detection of OSB of 80% observed in this study could be sustained if diagnostic ultrasound were to be offered to all pregnant women. Consideration will need to be given to the question of whether an improved OSB detection rate will be worth the additional cost incurred in providing diagnostic ultrasound for every pregnant woman.

The efficacy of a serum screening service for neural-tube defects: the South Wales experience.

Serum-alpha-fetoprotein (AFP) levels were measured in more than 15 000 pregnant women in an investigation designed to examine the operational issues entailed in a large-scale population screening programme for antenatal detection of neural-tube defects. The proportion of open neural-tube defects (ONTD) terminated as a result of serum screening was 56.1% (66.6% for anencephaly and 40.7% for open spina bifida). The principle causes of poor efficacy were: failure of pregnant women to undergo screening (18.2% of ONTD were not screened); failure of the screening test to detect ONTD (20.4% of those screened were below the 90th centile); decisions against termination of detected ONTD (14% of ONTD detected by serum AFP were not terminated). Given present practices and knowledge it is doubtful whether overall efficacy levels above 65% for open spina bifida can be achieved under normal service conditions. The establishment of a regional or national screening programme on grounds of clinical efficacy alone may be premature. The decision would seem to hinge principally around a careful consideration of the economic issues.

KIE: In 1976, the Department of Health and Social Security provided funding to the South Wales Anencephaly and Spina Bifida Screening Group to examine the operational issues entailed in a large-scale screening program for prenatal detection of neural tube defects. The results of the study of serum alpha-fetoprotein levels in 15,000 pregnant women are reported. It is concluded that the establishment of a regional or national screening program on grounds of clinical efficacy alone is probably premature.

Epidemiology in anaesthesia. III: Mortality risk in patients with coexisting physical disease.

The Cardiff Anaesthetic Record System has been used to examine the hospital mortality rates and relative risks for patients having anaesthesia who have certain preoperative conditions coexisting with their disease requiring surgery. Each preoperative condition was associated with a higher mortality rate than occurred in patients with no preoperative condition (for example ischaemic heart disease 7%, diabetes 5.7%, no preoperative condition 0.5%). Mortality was greater for emergency than for elective operations. In contrast to an increasing mortality by age, the relative mortality risk decreased, suggesting that in older age groups coexisting disease may be less important than other risk factors in determining mortality.