A role for the ecological study in the developing world

Retrospective case-control or prospective (followup) studies are important epidemiological tools and have provided useful infonnation on exposure disease associations. Prospective studies would be the ideal option, but m.any countries (Particularly in the developing world) do not have the necessary infrastructure to follow people up. Both retrospective and prospective studies are, however, som.etim. es conducted without due regard for their own lim.itations. These lim.itations are exacerbated when m.easures of exposure or disease are based on a single measurement and where the population under study is homogeneous with regard to exposure. The former is responsible for regression dilution bias and the latter for a lack of contrasts between exposure groups. Both factors would attenuate any relationship between exposure and disease. Ecological studies in epidemiology are weaker in design than case-control or prospective studies, but in some circumstances an ecological approach, which looks at the prevalence of an exposure or disorder in a number ofareas of varying disease rates, may offer some advantages

Residual risk of transmission of HIV through blood transfusion in South Africa

Despite the ongoing review of donor recruitment criteria by local blood transfusion services and the developmnt of highly sensitive and specific testing for the presence of antibodies to HIV in blood and blood products, there remains a residue of HIV in donated blood. This is because of donors who are in the 'window period' between acquisition of HIV and seroconversion, human errors and limits to the sensitivity and specificity of current tests. Data available from a national survey of HIV seroprevalence in South African blood donors allowed for the estimation of the number of units screened negative but likely to be infected with HIV. Assuming window periods of 4,8 and 14 weeks, a test sensitivity of 99,9%, a specificity of 98,5% and a human error rate of 0,1%, the likely rate of HIV-infected blood in the South African blood transfusion supply ranges from 1,1 to 3,9/ 100 000 units, with a likely estimate of 2,2/100 000 units. In the current South African blood transfusion setting, between 8,1 and 28,2 units of blood per annum. will be HIV-positive with a likely estimate of 15,9 units. This corresponds to an odds ratio of between 1:90 909 and 1:25 641 units infected with HIV. These data are comparable with the risk in developed countries. The expected increase in the incidence and prevalence of HIV infection in all adult South African populations necessitates additional measures to ensure a blood supply which is as safe as possible. Some of these measures have already been taken by local blood transfusion services

Tobacco smoking and all-cause mortality in a large Australian cohort study: findings from a mature epidemic with current low smoking prevalence

This study finds that up to two-thirds of deaths in current smokers  in Australia can be attributed to smoking. Abstract Background The smoking epidemic in Australia is characterised by historic levels of prolonged smoking, heavy smoking, very high levels of long-term cessation, and low current smoking prevalence, with 13% of adults reporting that they smoked daily in 2013. Large-scale quantitative evidence on the relationship of tobacco smoking to mortality in Australia is not available despite the potential to provide independent international evidence about the contemporary risks of smoking. Methods This is a prospective study of 204,953 individuals aged ≥45 years sampled from the general population of New South Wales, Australia, who joined the 45 and Up Study from 2006–2009, with linked questionnaire, hospitalisation, and mortality data to mid-2012 and with no history of cancer (other than melanoma and non-melanoma skin cancer), heart disease, stroke, or thrombosis. Hazard ratios (described here as relative risks, RRs) for all-cause mortality among current and past smokers compared to never-smokers were estimated, adjusting for age, education, income, region of residence, alcohol, and body mass index. Results Overall, 5,593 deaths accrued during follow-up (874,120 person-years; mean: 4.26 years); 7.7% of participants were current smokers and 34.1% past smokers at baseline. Compared to never-smokers, the adjusted RR (95% CI) of mortality was 2.96 (2.69–3.25) in current smokers and was similar in men (2.82 (2.49–3.19)) and women (3.08 (2.63–3.60)) and according to birth cohort. Mortality RRs increased with increasing smoking intensity, with around two- and four-fold increases in mortality in current smokers of ≤14 (mean 10/day) and ≥25 cigarettes/day, respectively, compared to never-smokers. Among past smokers, mortality diminished gradually with increasing time since cessation and did not differ significantly from never-smokers in those quitting prior to age 45. Current smokers are estimated to die an average of 10 years earlier than non-smokers. Conclusions In Australia, up to two-thirds of deaths in current smokers can be attributed to smoking. Cessation reduces mortality compared with continuing to smoke, with cessation earlier in life resulting in greater reductions

Desegregating health statistics and health research in South Africa

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Risk factors for erectile dysfunction in a cohort of 108 477 Australian men

Objectives: To quantify relationships between erectile dysfunction (ED), ageing and health and lifestyle factors for men aged 45 years and older. Design: Cross-sectional, population-based study seeking data on health, sociodemographic and lifestyle facto

Hormonal contraceptive use and smoking as risk factors for high-grade cervical intraepithelial neoplasia in unvaccinated women aged 30–44 years: A case-control study in New South Wales, Australia

Background Human papillomavirus (HPV) vaccines protect against HPV types 16/18, but do not eliminate the need to detect pre-cancerous lesions. Australian women vaccinated as teenage girls are now entering their mid-thirties. Since other oncogenic HPV types have been shown to be more prevalent in women ≥30 years old, understanding high grade cervical lesions in older women is still important. Hormonal contraceptives (HC) and smoking are recognised cofactors for the development of pre-malignant lesions. Methods 886 cases with cervical intraepithelial neoplasia (CIN) 2/3 and 3636 controls with normal cytology were recruited from the Pap Test Register of NSW, Australia. All women were aged 30–44 years. Conditional logistic regression was used to quantify the relationship of HC and smoking to CIN 2/3 adjusted for various factors. Results Current-users of HC were at higher risk for CIN 2/3 than never-users [odds ratio (OR) = 1.50, 95%CI = 1.03–2.17] and risk increased with increasing duration of use [ORs:1.13 (0.73–1.75), 1.51 (1.00–2.72), 1.82 (1.22–2.72) for <10, 10–14, ≥15 years of use; p-trend = 0.04]. Ex-users had risks similar to never-users (OR 1.08, 95%CI = 0.75–1.57) regardless of duration of use. Current smoking was significantly associated with CIN 2/3 (OR = 1.43, 95%CI = 1.14–1.80) and risk increased with increasing number of cigarettes/day (p-trend = 0.02). Among ex-smokers, the risk of CIN 2/3 decreased with increasing time since quitting (p-trend = 0.04). Conclusions In this benchmark study, current, long term users of HC and current smokers of ≥5 cigarettes/day were each at increased risk of developing CIN 2/3. Findings support smoking cessation in relation to decreasing the risk of pre-cancerous lesions and reinforce the continuing need for cervical screening for cancer prevention in vaccinated and unvaccinated populations