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Biomedical subjects

K McPherson

Publications and source records attributed to K McPherson.

At least 181 records · Page 10Linked to original sources
PubMed1986

The ability of women to recall their oral contraceptive histories.

Self-reported contraceptive histories were obtained at interview from 99 women and compared with prospectively collected data from the Oxford-Family Planning Association cohort study. The effect of different memory aids was evaluated and an assessment was made of the completeness and accuracy of contraceptive histories recorded in general practice notes. Accuracy of recall of total duration of use was sufficiently good to establish the presence or otherwise of a duration-response relationship and could be improved by the use of a contraceptive calendar. Recall of specific brands used was less accurate. In studies where accurate information on use of particular preparations is required, the use of a photo album is recommended, supplemented by data obtained from general practice records to improve the accuracy of dates. General practice records on their own are not sufficiently complete to be used as a sole source of exposure data in studies in which it is important to obtain a complete oral contraceptive history.

Adult↗
PubMed1986

Early oral contraceptive use and breast cancer: theoretical effects of latency.

Many cancers and other chronic diseases are associated with a long delay between exposure to a putative risk factor and subsequent diagnosis. This presents well recognised problems in the elucidation of suspected risk factors by epidemiological methods. In this paper we discuss the interpretation in epidemiological studies of the effect of a possible risk factor when population exposure is recent and rapidly changing. An important contemporary example concerns the study of early oral contraceptive (OC) use in relation to the subsequent risk of breast cancer. Computer simulations reported here indicate that plausible delays in the manifestation of any effect on breast cancer incidence make it difficult to exclude early OC use as a risk factor for breast cancer, even when large well conducted epidemiological studies show no apparent increased risk. Methods for detecting a 'latent' effect are discussed.

Breast Neoplasms↗
PubMed1985

The effects of hospital admission for bed rest on the duration of twin pregnancy: a randomised trial.

212 women with twin pregnancies were randomly allocated either to receive advice to rest in hospital from 32 weeks' gestation until delivery, or to be part of a control group in which hospital admission was offered selectively (and, on average, 5 weeks later). Preterm delivery was more common among women admitted routinely for bed rest than among controls, and this difference was unlikely to have occurred by chance. There is at present no scientifically acceptable evidence that this common, disruptive, and expensive obstetric policy does more good than harm.

Adult↗
PubMed1985

Increasing use of private practice by patients in Oxford requiring common elective surgical operations.

A random sample of 6000 people from eight general practices in and around Oxford was studied to ascertain their surgical histories and method of care received. The proportion of operations that were performed privately had increased with time and had a steep gradient according to social class. Different procedures had different likelihoods of being performed privately, but the age and sex of the patient had a non-significant association with private surgery. Adjustment for possible confounding variables using logistic analysis indicated that in the 1980s elective surgery is five times more likely to be performed privately than it was at the institution of the National Health Service.

Adult↗
PubMed1985

Socioeconomic variations in the use of common surgical operations.

The surgical experience of a sample of people aged 40-64 randomly selected from general practice lists was elicited by means of a postal questionnaire and the results examined in relation to two indicators of socioeconomic status. Eighty per cent of the sample had had one or more surgical operations and women had a higher mean number of operations than men. Those in the more advantaged groups had a higher mean number of operations than those in the less advantaged groups. This difference was, however, mainly accounted for by operations carried out in childhood before the establishment of the National Health Service and by private sector surgery.

Adult↗
PubMed1985

Effect of vegetarianism on development of gall stones in women.

Real time ultrasonography was used to compare the prevalence of gall stones in two groups of women aged 40-69: 632 women recruited from general practice registers and 130 vegetarians. One hundred and fifty-six (25%) of the 632 women who ate meat and 15 (12%) of the 130 vegetarian women either had gall stones visible on ultrasonography or had previously undergone cholecystectomy (p less than 0.01). The prevalence of gall stones was found to increase with age and body mass index. The 2.5 fold increase in risk of developing gall stones in non-vegetarians compared with vegetarians was reduced to 1.9 when controlling for these two potentially confounding factors, but remained significant. A family history of gall stones was reported more often by women with gall stones, but no association was found with parity or use of exogenous oestrogens. Thus the importance of age and obesity to determine the prevalence of gall stone was confirmed, and a dietary factor associated with vegetarianism may prevent this common condition.

Adult↗
PubMed1985

Precision of cell density estimates and endothelial cell loss with age.

The precision of estimating endothelial cell density of the cornea, using a noncontact method of specular microscopy, was assessed by asking eight individuals with known densities in one operated-on and one unoperated-on eye to have photography on two occasions in the same day. Three photographs of each eye were assessed by two individuals using masking procedures. Interobserver differences were negligible and estimates were similar except for one eye with low density values. The method was applied to a natural history study in which 103 eyes had cell-density estimates at zero and two years, and mean cell loss was found to be 2%. A collateral study using only good photographs that were available at both zero and two years showed a similar loss of 1.86% and reduced the number of counts showing unexpectedly high gains and losses.

Aging↗
PubMed1985

A randomized controlled trial of prophylactic cytotoxic chemotherapy in potentially curable breast cancer.

A randomized controlled trial of the value of oral adjuvant cytotoxic chemotherapy in the treatment of potentially curable breast cancer has been in progress in the Oxford Region since 1977. Eighty-seven patients were allocated to treatment with melphalan 0.2 mg/kg for 5 consecutive days every 6 weeks for 2 years; 98 patients were allocated to treatment with oral combination therapy consisting of melphalan 10 mg daily for 5 consecutive days, plus methotrexate 15 mg and 5-fluorouracil 250 mg on the first day, courses being repeated every 6 weeks for 2 years; and 88 patients were allocated to a control group which received no adjuvant chemotherapy. So far, 125 patients have suffered a recurrence of breast cancer and 85 have died. No statistically significant differences in outcome are apparent between the three treatment groups, although there is some indication of a beneficial effect of chemotherapy on disease-free interval in pre-menopausal women. Toxic effects of treatment, notably nausea, vomiting and bone marrow depression, have been moderately severe. In our view, the beneficial effects of current adjuvant cytotoxic chemotherapy, if any, are too modest to justify the suffering which such treatment can cause at a time when a woman with breast cancer might otherwise expect to feel physically well.

Adult↗
PubMed1985

Body size and survival in premenopausal breast cancer.

The survival experience of 582 women with premenopausal breast cancer was examined to determine whether prognosis was related to body size or to demographic and reproductive factors. During the follow-up period 228 patients died and 18 emigrated or were lost to follow-up. Usual body weight, reported at the time of diagnosis, was a strong predictor of survival, with a statistically significant trend towards lower survival with increasing weight. Height and obesity (Quetelet index) were not significantly related to survival, although the tallest women and the most obese women appeared to fare worst. Other characteristics of prognostic importance were disease stage and reproductive history (women who were older when their first child was born fared better). Women aged 46-50 when diagnosed also appeared more likely to survive but no clear trend with age was evident. Other characteristics of the women including social class, cigarette use and oral contraceptive use were not significantly related to survival probability.

Adult↗
PubMed1985

Do cholecystectomy rates correlate with geographic variations in the prevalence of gallstones?

Two fold variations in the age and sex standardised post mortem prevalence of gallstones have been demonstrated between nine British towns by Barker and his colleagues. We have examined the rates of cholecystectomy in the Districts serving seven of these towns to discover whether the incidence of operation bears any relation to this variation in morbidity. The opportunity to compare independent measurements of morbidity with the supply of health services and their use is rare, and in this example a plausible association is demonstrated. Variations in cholecystectomy rates between countries is, however, more difficult to explain by variations in relevant morbidity.

Cholecystectomy↗
PubMed1985

Oral contraception and serious psychiatric illness: absence of an association.

The incidence of serious psychiatric illness, as measured by first referral to hospital for specialist advice and treatment, has been investigated among 16,746 women taking part in the Oxford Family Planning Association contraceptive study. Of these women, 9,504 were recruited while using oral contraceptives, 4,144 while using a diaphragm and 3,098 while using an intrauterine device. The results are reassuring with respect to oral contraceptive use. First referral rates per 1000 woman-years of observation in the oral contraceptive, diaphragm, and intrauterine device entry groups were 3.0, 2.6, and 2.8 respectively for non-psychotic psychiatric disorders and 0.46, 0.43 and 0.53 respectively for psychotic disorders. Attempted suicide occurred only 40% as often amongst diaphragm users as amongst users of oral contraceptives or intrauterine devices; this finding presumably reflects the characteristics of women who choose the diaphragm as their birth control method.

Adult↗