The Australian longitudinal study on male health sampling design and survey weighting: implications for analysis and interpretation of clustered data.

BACKGROUND: The Australian Longitudinal Study on Male Health (Ten to Men) used a complex sampling scheme to identify potential participants for the baseline survey. This raises important questions about when and how to adjust for the sampling design when analyzing data from the baseline survey. METHODS: We describe the sampling scheme used in Ten to Men focusing on four important elements: stratification, multi-stage sampling, clustering and sample weights. We discuss how these elements fit together when using baseline data to estimate a population parameter (e.g., population mean or prevalence) or to estimate the association between an exposure and an outcome (e.g., an odds ratio). We illustrate this with examples using a continuous outcome (weight in kilograms) and a binary outcome (smoking status). RESULTS: Estimates of a population mean or disease prevalence using Ten to Men baseline data are influenced by the extent to which the sampling design is addressed in an analysis. Estimates of mean weight and smoking prevalence are larger in unweighted analyses than weighted analyses (e.g., mean = 83.9 kg vs. 81.4 kg; prevalence = 18.0 % vs. 16.7 %, for unweighted and weighted analyses respectively) and the standard error of the mean is 1.03 times larger in an analysis that acknowledges the hierarchical (clustered) structure of the data compared with one that does not. For smoking prevalence, the corresponding standard error is 1.07 times larger. Measures of association (mean group differences, odds ratios) are generally similar in unweighted or weighted analyses and whether or not adjustment is made for clustering. CONCLUSIONS: The extent to which the Ten to Men sampling design is accounted for in any analysis of the baseline data will depend on the research question. When the goals of the analysis are to estimate the prevalence of a disease or risk factor in the population or the magnitude of a population-level exposure-outcome association, our advice is to adopt an analysis that respects the sampling design.

Sleep apnoea in Australian men: disease burden, co-morbidities, and correlates from the Australian longitudinal study on male health.

BACKGROUND: Obstructive sleep apnoea is a common disorder with under-rated clinical impact, which is increasingly being recognised as having a major bearing on global disease burden. Men are especially vulnerable and become a priority group for preventative interventions. However, there is limited information on prevalence of the condition in Australia, its co-morbidities, and potential risk factors. METHODS: We used data from 13,423 adult men included in the baseline wave of Ten to Men, an Australian national study of the health of males, assembled using stratified cluster sampling with oversampling from rural and regional areas. Those aged 18-55 years self-completed a paper-based questionnaire that included a question regarding health professional-diagnosed sleep apnoea, physical and mental health status, and health-related behaviours. Sampling weights were used to account for the sampling design when reporting the prevalence estimates. Odds ratios were used to describe the association between health professional-diagnosed sleep apnoea and potential correlates while adjusting for age, country of birth, and body-mass index (BMI). RESULTS: Prevalence of self-reported health professional-diagnosed sleep apnoea increased from 2.2 % in age 18-25 years to 7.8 % in the age 45-55 years. Compared with those without sleep apnoea, those with sleep apnoea had significantly poorer physical, mental, and self-rated health as well as lower subjective wellbeing and poorer concentration/remembering (p < 0.001 for all). Sleep apnoea was significantly associated with older age (p < 0.001), unemployment (p < 0.001), asthma (p = 0.011), chronic obstructive pulmonary disease/chronic bronchitis (p = 0.002), diabetes (p < 0.001), hypercholesterolemia (p < 0.001), hypertension (p < 0.001), heart attack (p < 0.001), heart failure (p < 0.001), angina (p < 0.001), depression (p < 0.001), post-traumatic stress disorder (p < 0.001), other anxiety disorders (p < 0.001), schizophrenia (p = 0.002), overweight/obesity (p < 0.001), insufficient physical activity (p = 0.006), smoking (p = 0.005), and high alcohol consumption (p < 0.001). CONCLUSION: Health professional-diagnosed sleep apnoea is relatively common, particularly in older males. Associations between sleep apnoea and cardiovascular, metabolic, respiratory, and psychiatric disorders have important clinical and public health implications. As men are especially vulnerable to sleep apnoea as well as some of its chronic co-morbidities, they are potentially a priority group for health interventions. Modifiable lifestyle related factors such as smoking, alcohol consumption, level of physical activity and BMI are possible key foci for interventions.

Lower CSF MHPG predicts short-term risk for suicide attempt.

Post-mortem studies document alterations in the central noradrenergic system in suicide. However, studies of non-fatal suicide attempts have, thus far, found no consistent relationship to the noradrenaline metabolite 3-methoxy-4-hydroxphenylglycol (MHPG) in cerebrospinal fluid (CSF). We therefore conducted a prospective study of CSF MHPG and suicidal acts in major depression and bipolar depression. CSF MHPG was assayed in 184 drug-free patients with DSM-IV major depressive disorder or bipolar disorder, presenting for treatment of a current depressive episode, who were then followed-up for up to 12 months. Survival analysis was conducted using Cox proportional hazards modelling to test association of CSF MHPG and future suicidal behaviour, and potential clinical mediators. Twenty-seven individuals made a suicide attempt (two fatal) in the follow-up period. Lower CSF MHPG predicted future suicide attempt or suicide (22% increase in hazard for each 10 pmol/ml lower MHPG, p=0.045). Lower CSF MHPG also correlated with higher medical lethality of future suicidal act (mean MHPG: 49+/-18 vs. 32+/-12 pmol/ml for low- vs. high-lethality, t=2.8, d.f.=25, p=0.009). Smoking and self-rated depression severity were also associated with lower CSF MHPG and with future suicide attempt, but were not statistically significant mediators in multivariate models. In conclusion, lower CSF MHPG is associated with short-term risk for future suicidal behaviour in the 12 months following a major depressive episode. Psychopathology that mediates the relationship between lower CSF MHPG and future suicidal behaviour needs to be identified.

Suicide prevention strategies: a systematic review.

CONTEXT: In 2002, an estimated 877,000 lives were lost worldwide through suicide. Some developed nations have implemented national suicide prevention plans. Although these plans generally propose multiple interventions, their effectiveness is rarely evaluated. OBJECTIVES: To examine evidence for the effectiveness of specific suicide-preventive interventions and to make recommendations for future prevention programs and research. DATA SOURCES AND STUDY SELECTION: Relevant publications were identified via electronic searches of MEDLINE, the Cochrane Library, and PsychINFO databases using multiple search terms related to suicide prevention. Studies, published between 1966 and June 2005, included those that evaluated preventative interventions in major domains; education and awareness for the general public and for professionals; screening tools for at-risk individuals; treatment of psychiatric disorders; restricting access to lethal means; and responsible media reporting of suicide. DATA EXTRACTION: Data were extracted on primary outcomes of interest: suicidal behavior (completion, attempt, ideation), intermediary or secondary outcomes (treatment seeking, identification of at-risk individuals, antidepressant prescription/use rates, referrals), or both. Experts from 15 countries reviewed all studies. Included articles were those that reported on completed and attempted suicide and suicidal ideation; or, where applicable, intermediate outcomes, including help-seeking behavior, identification of at-risk individuals, entry into treatment, and antidepressant prescription rates. We included 3 major types of studies for which the research question was clearly defined: systematic reviews and meta-analyses (n = 10); quantitative studies, either randomized controlled trials (n = 18) or cohort studies (n = 24); and ecological, or population- based studies (n = 41). Heterogeneity of study populations and methodology did not permit formal meta-analysis; thus, a narrative synthesis is presented. DATA SYNTHESIS: Education of physicians and restricting access to lethal means were found to prevent suicide. Other methods including public education, screening programs, and media education need more testing. CONCLUSIONS: Physician education in depression recognition and treatment and restricting access to lethal methods reduce suicide rates. Other interventions need more evidence of efficacy. Ascertaining which components of suicide prevention programs are effective in reducing rates of suicide and suicide attempt is essential in order to optimize use of limited resources.