Biomedical subjects
S Gallivan
Publications and source records attributed to S Gallivan.
Cytological screening and management of abnormalities in prevention of cervical cancer: an overview with stochastic modelling.
AIMS: To develop a mathematical model of the histological changes of precancer and the development of invasive cancer and how these are related to cytological findings. To use this to investigate the effects on incidence of cervical cancer, number of smear tests and colposcopies, of different schedules for cervical screening, and the clinical management policies for dyskaryosis. METHODS: A stochastic model was developed relating the available data on tissue progression to the cytological findings. Two strategies, A and B, were compared: under A, women with any abnormal smear receive immediate colposcopy and treatment; under B, women with mild or borderline dyskaryosis have repeated smears at six monthly intervals with colposcopy only for persistent abnormalities. RESULTS: The model predicted an incidence of invasive cervical cancer in an unscreened population of women aged over 18 years of 5.9 per 10,000 per year. With 70% coverage and three yearly screening under strategy A, the incidence fell to 2.00 and under B to 2.10. The number of smears required was similar but A required two to three times as many colposcopies as B. Raising the coverage to 90% reduced the incidence to around 1 per 10,000 per year but changing the screening interval, the specificity or sensitivity of cytology had much less effect. CONCLUSION: The model has been tested under a wide range of possible variations in natural history, specificity and sensitivity of cytology. For low grade smear abnormalities, open colposcopic referral is predicted to reduce invasive cancer only slightly more than repeat cytology, at the expense of much additional colposcopy. Improving cytological coverage is suggested as more effective in reducing invasive cancer than increased use of colposcopy or more frequent screening.
An investigation of fetal growth using serial ultrasound data.
Serial ultrasonic measurements were performed in 67 Caucasian fetuses from 20 weeks' gestation until term to derive reference standards for abdominal circumference (AC) and estimated fetal weight (EFW). The variances of both AC and EFW increased with gestational age. Four mathematical models (linear, quadratic, Gompertz and Rossavik) were fitted to the log(10)(AC) and log(10)(EFW) data from each fetus using least squares regression analysis. The standard deviations of the residual error were greatest for the linear model. The linear model also overestimated the final log(10)(AC) while the linear, Gompertz and Rossavik models all overestimated the final log(10)(EFW) when these data were omitted from the fitting process. The individual quadratic constants were, therefore, used to produce 67 individual growth curves. Values of log(10)(AC) and log(10)(EFW) for each fetus at exact gestational ages between 20 and 40 weeks were derived by interpolation; the mean and standard deviation values were then used to derive centile ranges for abdominal circumference and estimated fetal weight. These standards should prove useful in the assessment of fetal growth.
Ultrasonic fetal weight estimation: analysis of inter- and intra-observer variability.
Standard ultrasound measurements were performed by two observers in 40 third-trimester fetuses. Observers were blinded to the results of the measurements. Estimated fetal weight (EFW) was calculated using two published formulae. The intra-observer standard deviation for EFW, assessed using one-way analysis of variance, was < 75 g for both observers. The 95% prediction intervals for inter-observer comparisons of EFW, calculated using the limits of agreement method, were -187.3 g to 139.8 g, and -159.9 g to 124.3 g, using the two formulae. The results suggest that measurements of EFW are reproducible. The prediction interval is comparable to the weekly fetal weight increment in normal fetuses.
Disability and distress following cardiac surgery in patients over 70 years of age.
We have reviewed the outcome in a consecutive series of 254 patients over the age of 70 undergoing cardiac surgery between 1987-89. Of the patients, 62% were male and the median age was 73 years. Operations included: coronary bypass 57%, valve replacement 26%, combinations 14% and other procedures 3%. The hospital mortality was 7.5% and late mortality was 13.8%. Complications included: intraaortic balloon 6%, resternotomy for bleeding 4%, permanent pacing 3%, chest infection 14%, tracheostomy 5%, major cerebrovascular events 3% and minor 4%. Eighty-two percent left the intensive care unit within 24 h and 89% left hospital within 8 days. Two questionnaires (York University) were sent to 207 patients believed to be alive in order to evaluate the change in their quality of life following surgery. Of the 207 questionnaires 197 (95%) were returned, 7 of which were from relatives of patients who had died and 7 were incomplete. The responses of 183 assessable patients (at a mean follow-up of 36 months) were converted into Rosser disability (I-VIII) and distress (A-D) groups. There was a decrease in disability and distress in 60% and 67%, respectively, no change in 34% and 30% and deterioration in 6% and 3%. Cardiac surgery can be carried out in elderly patients with an acceptable early morbidity and mortality, and although many patients show sustained improvement in their quality of life, this was not demonstrated in about a third of patients. As the emphasis in the elderly should be on quality of life we ought to continue to concentrate on careful selection in this age group.
Patient progress modelling for small cell lung cancer.
This paper describes the use of a mathematical technique called Patient Progress Modelling to reassess the results of an MRC trial on small cell lung cancer. The trial concerned patients treated initially with chemotherapy and radiotherapy and achieving at least a partial response. It compared the effects of giving maintenance chemotherapy with those of giving no maintenance therapy. The results of the MRC trial established that there was no significant survival difference between the two groups overall. However, it was observed that amongst patients achieving a complete response, those receiving maintenance chemotherapy had a small survival time advantage. The analysis described here suggests the hypothesis that this can be accounted for by differences in the pattern of deaths after relapse. There appeared to be little difference in the disease-free period.
Assessment of elderly people in general practice. 4. Depression, functional ability and contact with services.
The aim of this study was to look at the interrelationship between depression, physical disability and contact with services. In a random sample of 239 people aged 75 years and over from nine general practices in north London, depression (as measured by a shortened version of the comprehensive assessment and referral evaluation schedule) was found to be significantly associated with being a woman, and inability to perform a number of activities of daily living. Consumption of three or more prescribed medicines, a home visit by the general practitioner in the previous three months and contact with health visitors and home helps were all significantly more likely among depressed patients. There were also significant associations between loss of functional abilities, measured using items from an activities of daily living scale, and use of certain services: general practitioner home visits and reduced mobility indoors and both home help and district nurse visits to those with difficulty in bathing. Multiple logistic regression analysis suggested that contact with services was principally associated with loss of mobility, although contact with home helps was independently associated with depression, when adjustment was made for functional impairment.
Identification of fetal growth retardation: comparison of Doppler waveform indices and serial ultrasound measurements of abdominal circumference and fetal weight.
OBJECTIVE: To compare the serial ultrasound assessment of abdominal circumference (AC) and fetal weight versus single values of umbilical artery pulsatility index (PI) and the aortic-middle cerebral PI ratio in the identification of fetal growth retardation (FGR). METHODS: Serial AC measurements and estimates of weight were obtained in 104 small fetuses in the third trimester of pregnancy. These serial values (expressed as a change in standard deviation [SD] scores) were compared with the final value of AC and estimated fetal weight (EFW), umbilical artery PI, and the aortic-middle cerebral artery PI ratio (all expressed as SD scores) for their ability to predict a reduced neonatal ponderal index, mid-arm circumference-head circumference (HC) ratio, and skinfold thickness. Receiver-operating characteristic (ROC) curves were derived and the ultrasound measurements evaluated by calculating the areas under the ROC curves. RESULTS: Serial estimates of fetal weight resulted in a significantly larger area under the ROC curve compared with the final aortic-middle cerebral PI ratio in the prediction of an abnormal mid-arm circumference-HC ratio and compared with the final AC, EFW, and umbilical artery PI in the prediction of all neonatal morphometric indices. CONCLUSION: In small fetuses, fetal growth failure as determined by the serial assessment of AC and EFW was superior to the final AC and EFW, umbilical artery PI, and the aortic-middle cerebral PI ratio in the prediction of abnormal neonatal morphometry indicative of FGR.
Ultrasonic estimation of fetal weight: use of targeted formulas in small for gestational age fetuses.
OBJECTIVE: To derive a formula for calculating fetal weight in small for gestational age (SGA) fetuses and to determine prospectively whether the use of such a targeted formula reduces birth weight prediction errors. METHODS: Standard ultrasonic measurements were made in 159 SGA fetuses within 7 days of delivery. Three classes of fetal weight formulas (linear, quadratic, and cubic) were fitted to the data using stepwise regression analysis. Birth weight predictions using these three formulas were then compared prospectively with five previously reported formulas in 187 SGA fetuses. RESULTS: R2 was 0.97 for each of the three derived formulas. The 95% prediction intervals were comparable for the three formulas (eg, cubic model -11.6, 17.8%), and none were statistically superior to previous formulas. Each of the formulas evaluated prospectively had a systematic error and, with the exception of the present study's linear formula, all had percentage errors that varied systematically over the range of actual birth weights. CONCLUSION: Clinically useful birth weight predictions can be made in SGA fetuses, although no particular formula estimates birth weight significantly more accurately than any other.
Randomised controlled trial of Doppler ultrasound screening of placental perfusion during pregnancy.
We have done a randomised controlled trial to assess the effect on primary management and outcome of routine doppler ultrasound examinations of the umbilical and uterine arteries during pregnancy. Over 9 months, 2600 women with singleton pregnancies were recruited from a general obstetric population. Of 2475 women who delivered in hospital after 20 weeks' gestation, 1246 had been allocated at random to receive standard antenatal care with routine doppler examinations. The first doppler ultrasound was done at 19-22 weeks' gestation, and thereafter examinations were monthly if the pregnancy was considered high risk (192) or once at 32 weeks if considered low risk (1054). The control group of 1229 women received standard, antenatal care without doppler ultrasonography. The study groups did not differ in number of antenatal admissions or cardiotocographs, gestational age at delivery, method of delivery, frequency of deliveries with fetal distress, or need for resuscitation or admission to the neonatal intensive care unit. More perinatal deaths occurred in the doppler group (17 vs 7, relative risk 2.4, 95% Cl 1.00-5.76), but only 1 of 11 normally formed stillbirths and none of the 4 normally formed neonatal deaths after 24 weeks' gestation had an abnormal umbilical-artery doppler examination. We did not demonstrate any improvement in neonatal outcome by routine doppler ultrasound screening of a general obstetric population.
Are elderly people living alone an at risk group?
OBJECTIVE: To test the hypothesis that elderly people living alone are an at risk group with a high level of morbidity that makes high demands on health and social services. DESIGN: Secondary analysis of data from a community survey of 239 people aged 75 and over, identified from general practitioners' age-sex registers. SETTING: Nine practices in the London boroughs of Brent and Islington. MAIN OUTCOME MEASURES: Scores on the mini-mental state examination; stated satisfaction with life; assessment of mobility; numbers of diagnoses of major physical problems; numbers of prescribed drugs taken; urinary incontinence; alcohol consumption; contacts with general practitioners and hospital outpatient and inpatient services; contact with community health and social services. RESULTS: There were significantly more women among those living alone (93/120 (78%) v 63/119 (53%); p < 0.0005) and the median age of elderly people living alone was higher (81 v 80; p < 0.04). Those living alone and those living with others showed no significant differences in measures of cognitive impairment, numbers of major physical diagnoses, impaired mobility, or use of general practitioner or hospital services. Stated satisfaction with life was somewhat higher in those living alone. Elderly people living alone were significantly more likely to have contact with chiropody, home help, and meals on wheels services and less likely to have someone they could contact in an emergency or at night. Living alone increased the likelihood of contact with one or more community health professionals (district nurses, health visitors, or chiropodists) considered as a group and also increased the likelihood of contact with social services as a whole. There was a tendency for more of those living alone than those living with others to have home visits from their general practitioners, but there were no significant differences in contact with hospital services between the two groups. CONCLUSIONS: Elderly people living alone do not have an excess of morbidity compared with those living with others and do not seem to be an at risk group requiring specifically targeted assessments. More help is needed to provide elderly people living alone with a point of contact in case of emergency.
Computer system for assisting with clinical interpretation of tumour marker data.
OBJECTIVE: To design and evaluate a computer advisory system for the treatment of gestational trophoblastic tumour. DESIGN: A comparison of clinicians' treatment decisions with those of the computer system. Two datasets were used: one to calibrate the system and one to independently evaluate it. SETTING: Department of medical oncology. PATIENTS: Computerised records of 290 patients with low risk gestational trophoblastic tumour for whom the advisory system could predict the adequacy of treatment. The calibration set comprised patients admitted during 1979-86(227) and the test set patients during 1986-89(63). MAIN OUTCOME MEASURES: The system's accuracy in predicting need to change treatment compared with clinicians' actions. The mean time faster that the system was in predicting the need to change treatment. RESULTS: On the calibration dataset the system was 94% (164/174) accurate in predicting patients whose treatment was adequate, recommending change when none occurred in only 10 (6%) patients. In patients whose treatment was changed the system recommended change earlier than clinicians in 39/53 cases (74%), with a mean time advantage of 14.9 (SE 2.02) days. On the test dataset the system had an accuracy of 91% (31/34) in predicting treatment adequacy and a false positive rate of 9% (3/34). The system recommended change earlier than clinicians in 22/29 cases (76%), with a mean time advantage of 12.5 (2.22) days. CONCLUSIONS: The computer advisory system could improve patient management by reducing the time spent receiving ineffective treatment. This has implications for both patient time and clinical costs.
Plain film reporting in the UK.
A survey has been carried out to investigate the extent of non-reporting and delayed reporting of plain radiographs in UK hospitals. The survey took the form of a confidential postal questionnaire to all consultant radiologists in the UK. Five hundred and sixty-five replies were included in the study, representing 45% of the total consultant workforce. The majority of respondents (58%) indicated their belief that all plain films should be reported by a radiologist. However, only 16% stated that all films were reported, and 22% stated that more than 10% of films were never reported. The principal categories of films not reported were: out of date, dental, fracture clinic follow-up and orthopaedic out-patients. The commonest reason given for non-reporting was the near certainty that the report would be too late to influence clinical management. Although such a survey cannot be used to estimate precise prevalence, it does show that large numbers of radiological examinations go unreported, or are reported after the films have been returned from the referring clinician. The level of non-reporting is at variance with the stated ideals of the majority of radiologists questioned. Further research is needed to establish the clinical importance of present levels of non-reporting and delayed reporting.
Alcohol consumption by elderly people: a general practice survey.
A random sample of 241 patients from General Practice registers in London were interviewed to assess alcohol consumption, cognitive impairment, depression and other factors. Fifty-one per cent of men and 22% of women reported use of alcohol in the previous 3 months. No significant association was found between reported drinking status and age, score on a depression scale, falls in the previous 3 months, attendance at outpatient clinics or inpatient care in the previous year. In the men abstainers were significantly more likely to show cognitive impairment than were drinkers. Amongst those respondents who admitted to drinking within the previous 3 months, total stated weekly alcohol consumption was not associated with age, cognitive impairment and scores on the depression scale, and there was no association with falls, or with outpatient or inpatient care. Only three men (3.6%) and five women (3.2%) admitted consuming more than 21 and 14 units of alcohol per week, respectively.
Comparison of the prevalence of reversible airways obstruction in rural and urban Zimbabwean children.
The prevalence of reversible airways obstruction has been assessed in children in three areas in Zimbabwe--northern Harare (high socioeconomic class urban children), southern Harare (low socio-economic class urban children), and Wedza Communal Land (rural children from peasant families). Peak expiratory flow (PEF) was measured before and after six minutes' free running in 2055 Zimbabwean primary school children aged 7-9 years. Height and weight were measured and nutritional state expressed as a percentage of the 50th centile for age (Tanner-Whitehouse standards). Reversible airways obstruction was deemed to be present when peak expiratory flow was below the 2.5th centile for height before exercise and rose by more than 15% after inhalation of salbutamol and when it fell by 15% or more after exercise and rose again after salbutamol. The prevalence of reversible airways obstruction was 5.8% (95% confidence interval 4.1-7.5%) in northern Harare (n = 726); 3.1% (1.8-4.5%) in southern Harare (n = 642), and 0.1% (0.0-0.4%) in Wedza (n = 687). In northern Harare, the only study area in which white children were found, the prevalence of reversible airways obstruction was similar in white (5.3%, 10/188) and black (5.9%, 32/538) children. Indicators of nutritional state also showed no significant differences between white and black children in northern Harare but were lower in southern Harare and lower still in Wedza. Urban living and higher material standards of living appear to be associated with a higher prevalence of reversible airways obstruction in children in Zimbabwe.
Assessment of elderly people in general practice. 1. Social circumstances and mental state.
A survey of patients aged 75 years and over registered with general practitioners in north and north west London was carried out by trained interviewers to investigate cognitive impairment. A random sample of 239 patients was selected for the more detailed home assessment. General practitioners had seen nearly two thirds (65.3%) of their patients aged 75 years and over in the three months prior to the study, the majority of these consultations (82.1%) being initiated by the patient and occurring at the surgery. Half of the patients lived alone (50.2%), nearly one in three had no living siblings (31.9%), a similar proportion had no living children (29.5%), and contact with neighbours and relatives was relatively infrequent. One in five elderly patients had evidence of depression (22.0%) although this appeared to be severe in only two cases, and 36 participants (15.1%) had scores on the mini-mental state examination suggesting cognitive impairment. General practitioners underdiagnosed both dementia and depression. The population contained a small group of people who consumed alcohol on a daily basis (10.5%). This study showed that an annual assessment of elderly people as required by the new general practitioners' contract would yield much new evidence of depression and dementia and assist in the identification of heavy drinkers. Up to 30% of patients aged 75 years and over are likely to require further assessment on the basis of screening tests for depression and cognitive impairment, although it remains unclear to what extent identification of these patients will lead to improvements in outcome for them or their carers.
Assessment of elderly people in general practice. 3. Confiding relationships.
Little is known about the importance of confiding relationships in elderly people. Associations between lack of confiding relationships and depression, lifestyle characteristics, medication use, and contacts with doctors were studied by interviewing a random sample of 235 elderly people aged 75 years and over registered with nine general practices in inner London. It was found that men were not significantly more likely than women to report lack of confiding relationships. Married people of both sexes were more likely to have confiding relationships than those who were single, separated, divorced or widowed. Depression was not associated with lack of a confiding relationship, but those lacking such relationships were significantly more likely to smoke, and were prescribed significantly more medicines than those with confiding relationships. Individuals without a confiding relationship were significantly less likely to admit to any alcohol consumption in the previous three months, suggesting that alcohol consumption in this age group is largely a social phenomenon. Confiding relationships do not appear to confer strong protection against depression and a question on confiding relationships should not therefore be routinely incorporated into surveillance programmes for elderly people in the community.
Assessment of elderly people in general practice. 2. Functional abilities and medical problems.
A random sample of 239 patients aged 75 years and over registered with general practitioners in north and north west London was selected for home assessment to determine the functional abilities and medical problems of this group of patients. Nearly one in five of the patients were incontinent of urine (18.4%), although this was on a daily basis for only 4.1%. Around one in 20 patients were incontinent of faeces (5.9%), yet only one patient had laundry service support. Unassisted mobility outdoors was reported as possible by 81.2% of the patients. Fourteen different types of aids were present in the participants' homes, the commonest being walking sticks, bath aids and stair rails. Only a small proportion of aids seemed to be currently unused. The major functional problems were bathing, housework, shopping, washing and ironing, and cooking main meals, but the level of demand for extra help was low. One in five patients had a hearing aid (19.8%) but for only 30% of these patients was it in continuous use. Polypharmacy was common, with 29.7% of patients taking three or more prescribed medicines. The workload implications of this approach to anticipatory care of elderly people are considerable. In an average practice of 2000 patients with 130 patients aged 75 years and over the primary care team would need over 150 hours of face-to-face contact per year with these patients to fulfil the new contractual obligation and the yield of new information leading to effective medical or social intervention is limited.(ABSTRACT TRUNCATED AT 250 WORDS)