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Biomedical subjects

A R Walker

Publications and source records attributed to A R Walker.

At least 181 records · Page 10Linked to original sources
PubMed1993

Changes in total death rate and in ischaemic heart disease death rate in interethnic South African populations, 1978-1989.

Ischaemic heart disease (IHD) in prosperous Western populations rose markedly in the 1940s, peaked between 1970 and 1975 and then fell variably--by about 50% in the USA and Australia. Undoubtedly, decreases in serum cholesterol levels, in the incidence of hypertension and in smoking frequencies are largely responsible. In South Africa, in all population groups other than blacks, IHD rates rose analogously, with Asians and whites attaining very high rates. However, from 1978 to 1989, the total death rate among white males (per 100,000 world population) fell from 1,002 to 631 (37%), and the IHD mortality rate from 312 to 139 (56%). Rates for Asians were 1,306-1,130 (14%) and 355-226 (36%), respectively, and for coloureds 1,691 to 1,392 (18%) and 171 to 110 (36%). For blacks, the total mortality rate remained unchanged; IHD rates were low, but these data are unreliable. Percentage falls in the IHD rate exceed those in the total death rate, especially among whites, indicating true decreases in IHD rate. Understandably, the accuracy of the data, as with such data overseas, is questionable. Local falls are none the less in line with those noted in Western countries. Rates for whites remain very high, and are even higher for Asians. While knowledge of the reasons for the rises and falls in IHD rates remains incomplete, whites have none the less taken some preventive action, although Asians and coloureds apparently little.

Adult↗
PubMed1992

Screening for colorectal carcinoma: an analysis of the sensitivity of haemoccult.

The sensitivity of Haemoccult for asymptomatic colorectal carcinoma has been estimated in a large randomized controlled trial of mass population screening, with a minimum follow-up of 2 years. A total of 111 cancers were diagnosed in those who completed the screening tests; of these, 36 appear to have been missed by Haemoccult and 75 were detected by the test, giving an overall sensitivity of 67.6 per cent. Haemoccult was shown to be significantly more sensitive for carcinoma of the sigmoid and descending colon than for rectal or right-sided cancers (81 versus 45 and 47 per cent, respectively). The sensitivity was higher when tests were completed over 6 rather than 3 days (74 versus 65 per cent), but this difference was not statistically significant. There was no evidence for a detrimental effect on tumour stage of a false-negative Haemoccult test; indeed, a higher proportion of the interval cancers were Dukes' A tumours than cancers in the control group.

Aged↗
PubMed1992

Cost savings in mass population screening for colorectal cancer resulting from the early detection and excision of adenomas.

The widely-accepted hypothesis of a development sequence from colorectal adenoma to carcinoma is felt by clinicians to legitimate adenoma excision during routine colonoscopic investigation. Using published data on adenoma development, and adenoma prevalence data derived from the Nottingham colorectal cancer screening trial, the number of carcinomas prevented by early excision as a result of screening is predicted. The cost-effectiveness of early excision is then evaluated with reference to the expected treatment costs saved. These cost savings are found to represent a discount on the overall costs of mass population screening for colorectal cancer.

Adenoma↗
PubMed1992

Effect of subject age on costs of screening for colorectal cancer.

STUDY OBJECTIVE: The aim was to estimate costs and yields of faecal occult blood screening and rescreening for colorectal cancer, for differing age cohorts. DESIGN: Cost and clinical data were used as the basis for modelling the expected costs, and cost savings, resulting from the treatment of screen detected cancers, as compared with cancers detected by symptomatic presentation. SETTING: Data were derived from the MRC screening trial currently in progress in Nottingham. PARTICIPANTS: Approximately 140,000 subjects, age 50-79 years, were randomly allocated to a test (screened) and a control (unscreened) group. MAIN RESULTS: The net costs of detecting and treating a cancer following colorectal screening fall as the age of the target population increases, owing principally to the increasing incidence of the disease with age. Generally, the marginal detection and treatment costs falls for all age groups with the first screening round, but rises considerably with the second. If allowance is made for cancers prevented as a result of early detection and excision of adenomas, the costs of screening are substantially reduced for all age groups. CONCLUSIONS: Assuming a cost per QALY (quality adjusted life year gained) equivalent to that derived for the breast cancer screening programme, and a QALY gain from colorectal screening of one year, three screens, each separated by two years, appear economically justified for populations aged 60 years and above. Expected gains from cancer prevention make two screens justifiable for those between 45 and 59 years of age.

Age Factors↗
PubMed1992

Perplexing features in the occurrence of dental caries and its relationship to sugar intake.

Epidemiologically, there are numerous perplexing features, insufficiently appreciated, in the occurrences of degenerative diseases, and in the roles of their risk factors. This applies particularly to dental caries, the commonest of all diseases, and the risk factor, sugar intake. In some contexts, caries scores are much lower, or are much higher, than expected. Moreover, even in contexts where outwardly the same risk factors are widespread, ranges of scores are much wider than would be expected. In all contexts, among groups and more especially among individuals, the association of caries experience and dietary intakes, particularly that of sugar intake, is limited. Accordingly, caution must be exercised in the over-blaming of sugar and in the overclaiming of benefits to be derived from reducing intake.

Adult↗
PubMed1992

Cost-effective screening strategies for colorectal cancer.

This paper models a range of feasible strategies for mass population screening for colorectal cancer. It uses both clinical and economic data derived from the major colorectal cancer screening trial currently under way in Nottingham, supplemented by data from concurrent Scandinavian trials. Costs and yields for 12 strategies are modelled, and optima are identified according to a number of evaluation criteria. The cost-effectiveness condition for the desirability of introducing a programme of colorectal screening is also established.

Aged↗