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Biomedical subjects

I K Crombie

Publications and source records attributed to I K Crombie.

At least 109 records · Page 6Linked to original sources
PubMed1986

An investigation of data entry methods with a personal computer.

The features of three methods of data entry were investigated and a trial of them was carried out using operators with differing amounts of keyboard experience. The first method was a simple system of character entry using a word processing package, and the second and third systems were written in a commercial data base language; one was designed to possess limited intelligence, the other moderate intelligence. The amount of time and computing expertise required to set up each method increased in parallel with its sophistication. The most sophisticated method offered theoretical advantages of reduced error rates and increased keying rates but these were not realized in practice. The limited intelligence method, in which data were entered into a screen image of the record form, was fastest overall and was most popular with all users. This method together with verification by dual keying will provide a convenient, rapid, and high fidelity method of data entry. The simplest method was found to be adequate for short forms but incurred high error rates with longer forms.

Computers↗
PubMed1986

The use of microcomputers for data management in a large epidemiological survey.

A data management system designed around microcomputers and commercial software packages was employed for a large epidemiological study. Management involved the tracking of subjects through several stages of the study and the generation of subject listings, personalized letters of invitation, daily worklists for the field teams, and a checklist for the laboratories. These processes were controlled using a continually updated subject data base which in final form provided the core of the management system for the collected data. Data management presented major problems because of the volume of data which were received from several sources over a period of months. A key feature to emerge was the importance of an accurate serial number on all items for which a check digit was employed. The system had a short development time and was found to be inexpensive and flexible and to cope easily with the demands made of it.

Computers↗
PubMed1985

Comparison of response rates to a postal questionnaire from a general practice and a research unit.

A postal questionnaire study was carried out in an urban general practice to determine the effect of the introductory letter being sent by the participants' own general practitioner compared with that from a letter sent directly from a research unit. By sequential sampling 409 individuals aged between 40 and 59 were assigned to one of two groups. The people in one group were written to by their own general practitioner and those in the other by a doctor from a research unit. Husbands and wives were paired and were always sent the same letter. A second letter was sent to nonresponders after one month. The response rate to the general practitioner was significantly higher than that to the doctor in the research unit (85% compared with 75%) and differed by age and sex. The results have important implications for other research workers and suggest that general practitioners are in a key position in the conduct of medical and epidemiological research.

Adult↗
PubMed1984

Postmarketing drug surveillance by record linkage in Tayside.

The feasibility of conducting postmarketing drug surveillance by record linkage in Tayside was assessed. The key feature of the method is that all hospital discharge data are already computerised by the area health board and may be accessed through the unique community health number (CHNo) which has been allocated to all Tayside residents. The 12 861 prescriptions for cimetidine dispensed in Tayside over a nine month period were collected and the CHNo identified for 76%. These corresponded to 3802 individuals and their discharge data, together with those for an equal number of controls matched by age, sex, and general practitioner were retrieved from the computer. The expected excess of those diseases for which cimetidine is prescribed (peptic ulcer and oesophagitis) was observed. Other drug-disease associations were observed but may have been due to confounding and emphasise the inadequacy of community based controls. The major advantages of record linkage are, firstly, the low cost of the method, the present study costing just over pounds 12 000, and, secondly, the duration of patient follow up which may may be extended for as many years as required simply by rerunning the computer programs. To assemble large patient cohorts the study would have to be extended to other area health boards that are currently developing similar computer systems. Record linkage may provide a cost effective method for the follow up of patients to identify serious adverse drug reactions, particularly those that take several years to develop.

Cimetidine↗
PubMed1984

Insurance and the disabled.

The provision of life insurance for the disabled has been investigated to determine the extent to which the perceived disadvantage expressed by some disabled groups was real and, if real, justified. Life cover for a particular disability is likely to be offered only by the few companies with experience of it; however, the ratings charged appear usually to be a fair reflection of the limited and often poor information available. The response of organizations for the disabled to this problem has been reviewed, and possible strategies to enable the disabled to obtain insurance are suggested.

Actuarial Analysis↗
PubMed1981

Distribution of malignant melanoma on the body surface.

The distribution of malignant melanoma among the 4 major body sites (head, upper limb, lower limb and remainder (trunk) was investigated for 37 white populations. Although UV radiation is generally considered to be the major aetiological agent, it was found that approximately 75% of the tumours occurred on the relatively unexposed body sites. However, the sex differences in the incidence of melanoma at the various sites corresponded in direction and magnitude with the patterns of exposures of the sexes. The greatest difference between the sexes was the higher incidence on the female lower limb (the regular wearing of skirts results in a considerable exposure), and the next largest was the higher incidence on the male trunk (men can remove their shirts easily, but do not do so regularly). The results indicate that UV radiation is a major cause of malignant melanoma, but suggest that the mechanism of induction may be complex. Several hypotheses, as well as the types of additional evidence required, are discussed.

Arm↗
PubMed1981

Five-year age-specific incidence rates. II: The accuracy of calculations of expected number of tumours.

Five-year age-specific incidence rates were shown to produce small but systematic errors in the calculation of the expected number of tumours in a hypothetical but realistic study population. Underestimates occurred at younger ages (under 55) and overestimates at older ages, with a small overestimate (0.22%) overall. Larger errors (up to 12%) were obtained when there was a rapid change in the single-year age structure of the study population. Interpolation between five-year rates will normally produce an inaccurate set of one-year rates. It is shown, with the example of a logarithmic interpolation, that these rates tend to produce errors of similar size to the five-year rates but with a small underestimate overall (0.37%). However, the interpolated rates produced the smaller errors (up to 1%) when the study population age structure undergoes rapid change. A method is suggested for partially correcting the error in the interpolated rates.

Age Factors↗
PubMed1981

The limitations of case-control studies in the detection of environmental carcinogens.

The ability of the case-control study to detect human carcinogens has been investigated theoretically for varying fractions of the population exposed to hazards carrying different relative risks. The method is shown to be useful for the investigation of factors to which exposure is widespread (for example, common foods or beverages) but it is of limited use for the study of uncommon types of exposure, such as those associated with occupation. The case-control study is unable to detect very small relative risks (less than 1.5) even where exposure is widespread and large numbers of cases of cancer are occurring in the population. The principal limitation of the method is the maximum number of cases which can be recruited and analysed. It will only be through large-scale collaborative multicentre or international studies that important risk factors will be detected.

Carcinogens, Environmental↗
PubMed1980

Five-year age-specific incidence rates. I. Their nature and limitations.

The effect of population structure on five-year age-specific incidence rates was investigated using the one-year population data from life tables and a theoretical age incidence curve of the form: I = btk - where I is the incidence at age t, and b and k are constants. The five-year incidence rates differed systematically from the one-year rates of the central year of the five-year period. This difference depended on the change with age of both the population size and the incidence rate. Thus at ages 20-24 the five-year rate overestimates the mid-period one-year rate by about 4%, but the overestimate progressively decreases to become an underestimate of 0.5% at ages 75-79. In consequence the one-year and five-year rates produce fitted age incidence curves with different slopes; the value of k in the incidence equation is about 0.7% greater for the one-year rates. The population structures of developed and underdeveloped countries are markedly different and these were found to affect the five-year incidence rates, but never by more than 0.5%. The effect of the irregularities in one-year age structure of real populations on the observed five-year rates is also small, of the order of 0.5%. However, when incidence rates are calculated by recording tumours over several calendar years, these irregularities can create difficulties for the estimation of the appropriate denominator population. The use of the census population, even that of the central year of the observation period, can be in error by over 2%. A good method is to calculate the mean annual population of the observation period, estimating the intercensal year populations by interpolation between flanking censuses.

Adult↗
PubMed1979

Racial differences in melanoma incidence.

The incidences of malignant melanoma recorded by 59 population-based cancer registries were investigated to determine the effects of racial and skin-colour differences. White populations exhibited a wide range of melanoma incidences and females commonly, though not invariably, had a higher incidence than males. Non-white populations experienced in general a much lower incidence of melanoma although there was some overlap of white and non-white rates. No predominant sex difference emerged among non-whites. Populations of African descent were found to have a higher incidence than those of Asiatic origin, but it was concluded that this was due largely to the high frequency of tumours among Africans on the sole of the foot. A clear negative correlation between degree of skin pigmentation and melanoma incidence emerged for the exposed body sites. These data provide strong support for the hypotheses that UV radiation is a major cause of malignant melanoma and that melanin pigmentation protects against it. Further research is required to elucidate the aetiology of melanoma of the sole of the foot.

Arm↗