Estimating the prevalence of dementia using multiple linked administrative health records and capture–recapture methodology

Obtaining population-level estimates of the incidence and prevalence of dementia is challenging due to under-diagnosis and under-reporting. We investigated the feasibility of using multiple linked datasets and capture-recapture techniques to estimate rates of dementia among women in Australia.This work is based on the Australian Longitudinal Study on Women's Health. A random sample of 12,432 women born in 1921-1926 was recruited in 1996. Over 16\ua0years of follow-up records of dementia were obtained from five sources: three-yearly self-reported surveys; clinical assessments for aged care assistance; death certificates; pharmaceutical prescriptions filled; and, in three Australian States only, hospital in-patient records.A total of 2534 women had a record of dementia in at least one of the data sources. The aged care assessments included dementia records for 79.3% of these women, while pharmaceutical data included 34.6%, death certificates 31.0% and survey data 18.5%. In the States where hospital data were available this source included dementia records for 55.8% of the women. Using capture-recapture methods we estimated an additional 728 women with dementia had not been identified, increasing the 16\ua0year prevalence for the cohort from 20.4 to 26.0% (95% confidence interval [CI] 25.2, 26.8%).This study demonstrates that using routinely collected health data with record linkage and capture-recapture can produce plausible estimates for dementia prevalence and incidence at a population level

Visualising and modelling changes in categorical variables in longitudinal studies

Background: Graphical techniques can provide visually compelling insights into complex data patterns. In this paper we present a type of lasagne plot showing changes in categorical variables for participants measured at regular intervals over time and propose statistical models to estimate distributions of marginal and transitional probabilities. Methods. The plot uses stacked bars to show the distribution of categorical variables at each time interval, with different colours to depict different categories and changes in colours showing trajectories of participants over time. The models are based on nominal logistic regression which is appropriate for both ordinal and nominal categorical variables. To illustrate the plots and models we analyse data on smoking status, body mass index (BMI) and physical activity level from a longitudinal study on women's health. To estimate marginal distributions we fit survey wave as an explanatory variable whereas for transitional distributions we fit status of participants (e.g. smoking status) at previous surveys. Results: For the illustrative data the marginal models showed BMI increasing, physical activity decreasing and smoking decreasing linearly over time at the population level. The plots and transition models showed smoking status to be highly predictable for individuals whereas BMI was only moderately predictable and physical activity was virtually unpredictable. Most of the predictive power was obtained from participant status at the previous survey. Predicted probabilities from the models mostly agreed with observed probabilities indicating adequate goodness-of-fit. Conclusions: The proposed form of lasagne plot provides a simple visual aid to show transitions in categorical variables over time in longitudinal studies. The suggested models complement the plot and allow formal testing and estimation of marginal and transitional distributions. These simple tools can provide valuable insights into categorical data on individuals measured at regular intervals over time

Is intergenerational social mobility related to the type and amount of physical activity in mid-adulthood? Results from the 1946 British birth cohort study.

PURPOSE: Greater levels of leisure-time or moderate-vigorous physical activity have consistently been found in those with greater socioeconomic position (SEP). Less is known about the effects of intergenerational social mobility. METHODS: We examined the influence of SEP and social mobility on mid-adulthood physical activity in the Medical Research Council National Survey of Health and Development. Two sub-domains of SEP were used: occupational class and educational attainment. Latent classes for walking, cycling, and leisure-time physical activity (LTPA) were used, plus sedentary behavior at age 36. Associations between types of physical activity and SEP were examined with the use of logistic or multinomial logistic regression. RESULTS: Being a manual worker oneself or having a father who was a manual worker was, relative to nonmanual work, associated with lower levels of sedentary behavior and greater walking activity, but also with lower LTPA. Compared with those who remained in a manual occupational class, upward occupational mobility was associated with more sedentary behavior, less walking, and increased LTPA. Associations with downward mobility were in the opposite directions. Similar results were obtained for educational attainment. CONCLUSIONS: This study found clear evidence of social differences in physical activity. Persistently high SEP and upward social mobility were associated with greater levels of LTPA but also increased sedentary behavior and less walking

Association between inflammatory potential of diet and risk of depression in middle-aged women: the Australian longitudinal study on women's health

Dietary factors and inflammation markers have been shown to play a role in the development of depression. However, there are very few studies that have explored the association between inflammatory potential of diet and risk of depression. In this study, we examined the association between the dietary inflammatory index (DII), which was developed specifically to measure the inflammatory potential of diet, and risk of depression in the middle-aged cohort of the Australian Longitudinal Study on Women's Health. A total of 6438 women with a mean age of 52·0 (sd 1·4) years at baseline were followed-up at five surveys over 12 years (2001-2013). Depression was defined as a score of ≥10 on the Center for Epidemiologic Studies Depression-10 scale. The DII score, a literature-derived, population-based dietary index that has been validated against several inflammatory markers, was computed on the basis of dietary intake assessed using a validated FFQ. Generalised estimating equations were used to estimate relative risk (RR) of depression according to DII score. Models were adjusted for energy intake, highest education completed, marital status, menopause status and symptoms, personal illness or injury, smoking status, physical activity, BMI and depression diagnosis or treatment. In total, 1156 women (18 %) had scores≥10 on the CESD scale over the course of 9 years. Women with the most anti-inflammatory diet had an approximately 20 % lower risk of developing depression compared with women with the most pro-inflammatory diet (RRDII quartile 1 v. 4: 0·81; 95 % CI 0·69, 0·96; P trend=0·03). These results suggest that an anti-inflammatory diet is associated with lower risk of depression in middle-aged Australian women

Moderate agreement between self-reported stroke and hospital-recorded stroke in two cohorts of Australian women: a validation study

Background: Conflicting findings on the validity of self-reported stroke from existing studies creates uncertainty about the appropriateness of using self-reported stroke in epidemiological research. We aimed to compare self-reported stroke against hospital-recorded stroke, and investigate reasons for disagreement. Methods: We included participants from the Australian Longitudinal Study on Women's Health born in 1921-26 (n = 1556) and 1946-51 (n = 2119), who were living in New South Wales and who returned all survey questionnaires over a defined period of time. We determined agreement between self-reported and hospitalised stroke by calculating sensitivity, specificity and kappa statistics. We investigated whether characteristics including age, education, area of residence, country of birth, language spoken at home, recent mental health at survey completion and proxy completion of questionnaire were associated with disagreement, using logistic regression analysis to obtain odds ratios (ORs) with 95% confidence intervals (CIs). Results: Agreement between self-report and hospital-recorded stroke was fair in older women (kappa 0.35, 95% CI 0.25 to 0.46) and moderate in mid-aged women (0.56, 95% CI 0.37 to 0.75). There was a high proportion with unverified self-reported stroke, partly due to: reporting of transient ischaemic attacks; strokes occurring outside the period of interest; and possible reporting of stroke-like conditions. In the older cohort, a large proportion with unverified stroke had hospital records of other cerebrovascular disease. In both cohorts, higher education was associated with agreement, whereas recent poor mental health was associated with disagreement. Conclusion: Among women who returned survey questionnaires within the period of interest, validity of self-reported stroke was fair to moderate, but is probably underestimated. Agreement between self-report and hospital-recorded stroke was associated with individual characteristics. Where clinically verified stroke data are unavailable, self-report may be a reasonable alternative method of stroke ascertainment for some epidemiological studies

Health care costs associated with prolonged sitting and inactivity

Background Physical inactivity and prolonged sitting are associated with negative health outcomes. Purpose To examine the health-related costs of prolonged sitting and inactivity in middle-aged women. Methods Australian Longitudinal Study on Women's Health participants (born 1946-1951) answered questions about time spent sitting, walking, and in moderate and vigorous leisure activities in 2001 (n=6108); 2004 (n=5902); 2007 (n=5754); and 2010 (n=5535) surveys. Sitting time was categorized as low (0-4); moderate (5-7); and high (≥8 hours/day). Physical activity was categorized as inactive

Depression and the incidence of urinary incontinence symptoms among young women: results from a prospective cohort study

Objective To examine the association of depressive symptoms with subsequent urinary incontinence (UI) symptoms among young women. Subjects and methods Data were from a cohort of 5391 young women (born 1973-1978) from the Australian Longitudinal Study on Women's Health. Generalised Estimating Equations (GEEs) were used to link depressive symptoms, and history of doctor diagnosed depression at Survey 2 (S2) in 2000 with the incidence of UI symptoms in subsequent surveys (from S3 in 2003 to S6 in 2012). Results 24% of women reported the incidence of UI over the nine-year study period, while the prevalence rose over time from 6.8% (at S2, aged 22-27 years) to 16.5% (at S6, aged 34-39). From univariable GEE analysis, women with depressive symptoms or a history of depression were more likely to report subsequent UI symptoms. This remained after adjusting for socio-demographic, body mass index, health behaviours and reproductive factors, with depressive symptoms associated with 37% higher odds (odds ratio 1.37, 95% CI 1.16 to 1.61) and history of depression with 42% higher odds (1.42, 1.17 to 1.74) of incidence of UI. Conclusions When woman seek treatment for UI symptoms, health professionals should consider her current or history of depression

Health symptoms during midlife in relation to menopausal transition: British prospective cohort study

Objective To characterise symptoms experienced by women during the transition into natural menopause, to classify women into distinct symptom profiles or trajectories, and to relate these profiles to sociodemographic factors and health behaviours

Clustering of obesity-related risk behaviors in children and their mothers

PURPOSE: To examine the clustering and patterns of obesity-related behaviors in children and their mothers and the concordance between mother and child pairs