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Biomedical subjects

C D Holman

Publications and source records attributed to C D Holman.

At least 19 recordsLinked to original sources
PubMed1995

Misclassification of social disadvantage based on geographical areas: comparison of postcode and collector's district analyses.

BACKGROUND: Analysis of socioeconomic status (SES), defined on the basis of geographical area, will always be subject to misclassification of individuals. We studied the relationship between SES and selected health-related measures when SES was defined firstly on the basis of postcode and secondly on the basis of the smaller spatial area of collector's district (CD). METHOD: A Census population of 1.4 million was used to investigate the misclassification of individuals to SES group using postcode as opposed to CD. A field survey of 1000 respondents and a mortality register of 1756 deaths were used to compare the relationship between SES and certain outcome variables, when SES group was assigned using postcode and CD. Misclassification probability matrices were used to try to adjust the postcode-based results to approximate CD-based results. RESULTS: The Census data showed that nearly 50% of residents were misclassified into SES groups by the postcode-based system compared with a CD-based system. In comparing the most socially disadvantaged group with the least disadvantaged group, the postcode analysis underestimated the absolute effects of SES by 58% for the increased prevalence of smoking, by 19% for the reduced prevalence of participation in junior sporting clubs and by 13% for the increased mortality rate at ages 0-64 years. Adjustment of postcode-based results using misclassification matrices proved fruitless due to differential misclassification and technical difficulties. CONCLUSIONS: Misclassification of individuals to SES groups on the basis of postcode has caused an underestimation of the true relationship between SES and health-related measures. A reduction of this misclassification by using smaller spatial areas, such as CD or census enumeration districts, will provide improved validity in estimating the true relationship.

Adolescent↗
PubMed1995

An improved aetiologic fraction for alcohol-caused mortality.

A method is proposed for estimation of alcohol-caused mortality in which the aetiologic fraction of deaths is derived from an exposure contrast between the 'unsafe' drinker and 'safe' drinker; not between the drinker and the nondrinker. The method is consistent with the objectives of public health intervention in the alcohol education field. The 'safe' drinker is the reference exposure category and aetiologic fractions are obtained for the single categories of a multiple-level exposure scale, using separate relative risks for the 'unsafe' drinker and the nondrinker. Preliminary application of the method to Australian data yields an estimate of the number of deaths caused by misuse of alcohol that is larger than those obtained under the old conceptual model. Thus, the public health importance of unsafe alcohol consumption has been underrepresented.

Alcohol Drinking↗
PubMed1992

The effects of surgical treatment on survival and local recurrence of cutaneous malignant melanoma.

All patients with a diagnosis of cutaneous malignant melanoma (CMM) in Western Australia from 1980 to 1981 were observed for up to 6 years to determine vital status and to detect the development of local recurrences of the primary lesion. Approximately 35% of all patients had their tumors excised with surgical margins of less than 1 cm. When compared with patients whose tumors were excised with margins of at least 2 cm, the fatality rate in those with narrow margins was slightly less (rate ratio, 0.60; 95% confidence interval [CI], 0.20% to 1.80% for margins of 5 to 9 mm; rate ratio, 0.69; 95% CI, 0.26% to 1.87% for margins of 1 to 4 mm); however, this difference could have been caused by chance alone. The risk of local recurrence within 5 years after diagnosis was 2% (95% CI, 1% to 4%). The risk was strongly related to age and tumor thickness, but did not appear to be influenced by the width of excision (greater than 1 cm versus less than 1 cm: rate ratio, 1.03; 95% CI, 0.25% to 4.34%). The apparent lack of effect could be caused by to chance alone because the number of local recurrences was small.

Adult↗
PubMed1991

Survival among patients with clinical stage I cutaneous malignant melanoma diagnosed in Western Australia in 1975/1976 and 1980/1981.

Five-year survival rates were slightly higher for patients with cutaneous malignant melanoma (CMM) diagnosed in Western Australia in 1980/1981 (89% in men and 95% in women) than in those whose melanomas were diagnosed in 1975/1976 (88% in men and 91% in women). The improvement in survival was probably due to a decrease in median tumor thickness from 1.29 mm in 1975/1976 to 0.77 mm in 1980/1981 because tumor thickness was the most important histologic index of prognosis. Tumor cell type and cross-sectional profile were the only other histologic characteristics that independently influenced fatality rates. Prognosis was significantly worse in males than in females and in patients with tumors on the posterior head and neck. Ten-year survival rates of patients whose melanomas were diagnosed in 1975/1976 was 82% in men and 87% in women, indicating that these patients continued to experience some excess mortality up to 10 years after diagnosis. The comparatively small improvement in prognosis in the 5-year period between these two groups suggests that survival might be expected to continue to improve only gradually unless there is a sharp absolute decrease in the number of thick tumors diagnosed.

Adolescent↗
PubMed1990

Dental caries experience in schoolchildren in fluoridated and non-fluoridated communities in Western Australia.

A cross-sectional survey was undertaken in 1987 to measure the difference in caries experience in schoolchildren between a fluoridated (0.8 mg/L F-) and a non-fluoridated region (0.1-0.4 mg/L F-). 3436 children aged 5-15 yr were examined. Children in the non-fluoridated region had a higher caries experience than those in the fluoridated region. Mean differences were 1.06 dfs (95% CI = 0.66 to 1.47, P less than 0.001) and 0.48 DFS (95% CI = 0.23 to 0.72, P less than 0.001). After adjusting for potential confounding factors (fluoride tablet consumption, socioeconomic status, number of fissure-sealed surfaces, and mobility between regions) the relative risk of not being caries-free in the non-fluoridated region compared with the fluoridated region was 1.43 (95% CI = 1.21-1.70, P less than 0.0001) for the primary dentition and 1.39 (95% CI = 1.18-1.63, P less than 0.0001) for the permanent dentition.

Adolescent↗
PubMed1990

Methodology used to monitor and evaluate in vitro fertilization and related procedures in Western Australia, 1983-1987.

A methodology was developed to support a comprehensive health services research project undertaken to monitor and evaluate the practice of in vitro fertilization (IVF) and related procedures, such as GIFT, in Western Australia (WA) from 1983 to 1987. The project included demographic, clinical and economic assessments of the new technology. The study subjects were the 1,240 couples who began IVF treatment between January 1, 1983 and December 30, 1986. Information was collected on all 2,982 treatment cycles commenced by June 30, 1987, and on the 273 births that resulted from these treatment cycles. Where relevant, comparisons were based on information obtained from the Australian Bureau of Statistics (ABS) census, the WA Midwives' Notification System and the WA Hospital Morbidity Data System. The need for long-term follow-up studies of children and participants is identified, as is the need for randomized clinical trials to evaluate more fully the success of the procedures where bilateral tubal blockage is not the indication for the treatment.

Cohort Studies↗
PubMed1989

Population-based epidemiology of human immunodeficiency virus infection in Western Australia. Western Australian AIDS Advisory Committee.

A total of 328 cases of infection with human immunodeficiency virus (HIV) in Western Australia in 1983-1987 was studied with respect to demographic factors, the risk profile, the clinical progression of disease, the utilization of inpatient services and trends in incidence over time. The crude incidence rates were 8.8 cases/100,000 person-years in men and 0.4 cases/100,000 person-years in women. Age-specific rates peaked at 25 to 29 years of age in men. The risk of HIV infection was associated with metropolitan residence, low socioeconomic level, and two specific occupational groups. Homosexual and bisexual men constituted 86% of all cases; the incidence rate of HIV infection in such men was approximately 1000-times higher than was the incidence rate by apparent sexual transmission in heterosexual persons. However, the proportion of cases that occurred in women or that apparently was caused by heterosexual sexual transmission increased from zero in 1983-1984 to 7.5% and 5.4%, respectively, in 1987. After two years of follow-up, 71% of preclinical (category-C) patients had developed signs, symptoms or evidence of immune dysfunction, and 12% of those patients with lymphadenopathy or with other early clinical features of disease (category-B) had progressed to the acquired immunodeficiency syndrome (AIDS). At 21 months of follow-up, the survival rate with AIDS was 9%. Patients with AIDS utilized an average of 68.9 short-stay hospital bed-days per person-year, while category-B patients used 11.5 hospital bed-days per person-year. Notifications of HIV infection increased each year from 1983 to 1986, but fell by 22% in 1987. The latter may have been as a result of chance, a screening artefact or a real reduction in the incidence rate.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Variation in hospital morbidity in the male workforce of Western Australia.

The associations of hospital morbidity with occupation were studied in Western Australian men of working age in 1981-2. Data on hospital morbidity were derived from a population based system that covered all short stays in hospitals in the state. Occupations were grouped into 12 major categories and conditions were coded using the International Classification of Diseases. Armed services personnel had the highest overall rate of hospital admissions, followed by transport and communications workers and by administrative and managerial workers. Injuries were the most common cause of referral to hospital. Four occupational groups, farmers and allied workers, miners and quarrymen, transport and communications workers, and craftsmen, production workers, and labourers were often associated with injury. Diseases of the musculoskeletal system and connective tissue were the second most common cause for referral and were increased in transport and communications workers, and in craftsmen, production workers, and labourers. Several other associations between causes of hospital admission and major occupational groups were observed, including associations of circulatory system diseases with professional and technical work and with administrative and managerial work. The excess of hospital admissions due to factors associated with occupation was estimated to be 12,665 admissions a year or 24.9% of the total in working men.

Adolescent↗
PubMed1987

Cervical cancer mortality trends in Australia--an update.

Trends in the mortality rate due to cancer of the cervix in Australian women were reviewed for the period 1950-1984, taking into account the changes in the proportion of women who have undergone a hysterectomy. Cohort-based increases in women who were born after 1935, which had been reported previously, were observed to extend into the 40 to 44 years' age group and to continue the upward trend in women aged 30-39 years. However, for women who were less than 30 years of age there was evidence of a recent fall in the rate of cervical cancer mortality.

Adult↗
PubMed1987

Occurrence and distribution of hepatitis B infection in the aboriginal population of Western Australia.

In 1986, the prevalences of hepatitis B surface antigen (HBsAg), and other serological markers of infection with hepatitis B virus in the Western Australian adult Aboriginal population, were estimated using a stratified random sample of 1,150 subjects. When the estimates were standardised to the age and sex distribution of the total population of aborigines aged 12 years or over, the prevalence of HBsAg was 7% (95% confidence interval 6-9%). The prevalence of any marker, that is HBsAg and/or hepatitis surface antibody (anti-HBs), was 49% (44-54%). The follow-up blood specimens obtained from three-fifths of the antigenemic subjects indicated that 96% (88-99%) were hepatitis B carriers. Male subjects had twice the prevalence of HBsAg (10%; 7-13%) when compared with females (4%; 3-6%). However, there was only a modest elevation of the prevalence of any marker in men (53%) compared with women (46%). There was evidence that the prevalence of HBsAg increased with age, but this was not the case with any marker. Geographically, there was substantial variation in hepatitis B infection rates. The Eastern Goldfields region had the highest prevalence (HBsAg 12%; any marker 66%), followed by the Kimberley, Pilbara and Central regions (HBsAg 7-9%; any marker 56-59%). The lowest rates were evident in Perth and the South West (HBsAg 3-5%; any marker 23-25%). The highest prevalence of markers in any discrete community was observed in the desert people of Warburton (HBsAg 22%; any marker 85%). These data indicate that, according to World Health Organisation criteria, the aboriginal population of Western Australia has an intermediate to high risk of infection with hepatitis B.

Adolescent↗
PubMed1987

Determinants of chronic bronchitis and lung dysfunction in Western Australian gold miners.

The relation of chronic bronchitis and respiratory dysfunction to age, tobacco smoking, and occupational exposure to surface and underground mining operations were examined in a cross sectional survey of 1363 men employed in the Kalgoorlie mining industry in 1985. Overall, the prevalence of chronic bronchitis was 14%. Eleven per cent of the workers had obstructive lung disorder (FEV1/FVC less than 0.70) and 9% had restrictive lung disorder (FVC less than 0.80 of predicted for height and age). There was little change in the prevalence of chronic bronchitis from that observed in a survey of the same industry in 1961-2. Only 1% of the workers in 1985 had radiographic signs of silicosis compared with 22% in 1961-2. Age, smoking, and underground mining experience all exerted strong effects on the development of chronic bronchitis with or without associated respiratory function abnormalities. After control of confounding by age and smoking, it was estimated that compared with a lifetime non-miner, the odds ratio (OR) of chronic bronchitis was 1.8 (95% confidence interval, 1.0-3.3) for one to nine years underground mining gold, 2.5 (1.2-5.2) for 10-19 years, and 5.1 (2.4-10.9) for 20 or more years. Underground mining of minerals other than gold was also associated with chronic bronchitis (OR = 5.1; 95% CI, 1.1-25.0) whereas exclusive surface mining had only a small empirical effect (OR = 1.3; 95% CI, 0.6-2.5). It is estimated that the proportion of cases of chronic bronchitis in working underground miners due to occupational factors is 50%. The results support the existence of an industrial cause of chronic bronchitis, although caution must be exercised in generalising the results to miners with progressive and sever respiratory impairment.

Adolescent↗