Prevalence and patterns of multimorbidity in Australian baby boomers: the Busselton healthy ageing study.

BACKGROUND AND OBJECTIVE: Chronic medical conditions accumulate within individuals with age. However, knowledge concerning the trends, patterns and determinants of multimorbidity remains limited. This study assessed the prevalence and patterns of multimorbidity using extensive individual phenotyping in a general population of Australian middle-aged adults. METHODS: Participants (n = 5029, 55% female), born between 1946 and 1964 and attending the cross-sectional phase of the Busselton Healthy Ageing Study (BHAS) between 2010 and 2015, were studied. Prevalence of 21 chronic conditions was estimated using clinical measurement, validated instrument scores and/or self-reported doctor-diagnosis. Non-random patterns of multimorbidity were explored using observed/expected (O/E) prevalence ratios and latent class analysis (LCA). Variables associated with numbers of conditions and class of multimorbidity were investigated. RESULTS: The individual prevalence of 21 chronic conditions ranged from 2 to 54% and multimorbidity was common with 73% of the cohort having 2 or more chronic conditions. (mean ± SD 2.75 ± 1.84, median = 2.00, range 0-13). The prevalence of multimorbidity increased with age, obesity, physical inactivity, tobacco smoking and family history of asthma, diabetes, myocardial infarct or cancer. There were 13 pairs and 27 triplets of conditions identified with a prevalence > 1.5% and O/E > 1.5. Of the triplets, arthritis (> 50%), bowel disease (> 33%) and depression-anxiety (> 33%) were observed most commonly. LCA modelling identified 4 statistically and clinically distinct classes of multimorbidity labelled as: 1) "Healthy" (70%) with average of 1.95 conditions; 2) "Respiratory and Atopy" (11%, 3.65 conditions); 3) "Non-cardiometabolic" (14%, 4.77 conditions), and 4) "Cardiometabolic" (5%, 6.32 conditions). Predictors of multimorbidity class membership differed between classes and differed from predictors of number of co-occurring conditions. CONCLUSION: Multimorbidity is common among middle-aged adults from a general population. Some conditions associated with ageing such as arthritis, bowel disease and depression-anxiety co-occur in clinically distinct patterns and at higher prevalence than expected by chance. These findings may inform further studies into shared biological and environmental causes of co-occurring conditions of ageing. Recognition of distinct patterns of multimorbidity may aid in a holistic approach to care management in individuals presenting with multiple chronic conditions, while also guiding health resource allocation in ageing populations.

Vitamin D and respiratory health in the Busselton Healthy Ageing Study.

BACKGROUND AND OBJECTIVE: The relationship between vitamin D and respiratory disease was examined by cross-sectional analysis of a large community-based sample. METHODS: Serum 25-hydroxyvitamin D (25OHD) and history of respiratory disease, symptoms (recorded by questionnaire) and spirometry were measured in 5011 adults aged 45-69 years. Adjustments were made for age, sex, season and smoking (Model A), plus body mass index (BMI) and physical activity level (Model B), plus history of chronic diseases (Model C). RESULTS: Mean (SD) age was 58 (SD 6) years with 45% males, 10% current smokers and 12% taking vitamin D supplements. The prevalence of 25OHD level <50 nmol/L was 8.0%. In all the three models, 25OHD <50 nmol/L was significantly associated with asthma (Model C: odds ratio (OR): 1.32; 95% CI: 1.00, 1.73), bronchitis (1.54; 1.17, 2.01), wheeze (1.37; 1.10, 1.71) and chest tightness (1.42; 1.10, 1.83). Participants with vitamin D level > 100 nmol/L had higher forced vital capacity (FVC) in all the three models (1.17% higher, compared with the 50-100 nmol/L group in Model C). CONCLUSION: Low levels of serum 25OHD were independently associated with asthma, bronchitis, wheeze and chest tightness after three levels of adjustment for potential confounders. Higher vitamin D levels were associated with higher levels of lung function.

Plasma calcium as a predictor of cardiovascular disease in a community-based cohort.

OBJECTIVE: Primary hyperparathyroidism and calcium supplementation have been linked to cardiovascular outcomes. The study objective was to examine plasma calcium as a predictor of cardiovascular disease in the general population, as results from previous cohort studies are conflicting. DESIGN, PARTICIPANTS AND MEASUREMENTS: Plasma calcium was measured in 4003 participants (aged 25-84 years) in the 1994/1995 Busselton Health Survey. Using a Cox proportional hazards model, we examined albumin-corrected calcium as a predictor of total mortality, cardiovascular mortality and cardiovascular events up to the end of 2010. RESULTS: At baseline, there were significant positive relationships between plasma calcium and each of body mass index, systolic and diastolic blood pressure, glucose and total cholesterol. During the follow-up period, 666 participants died (278 from cardiovascular disease) and 652 had incident cardiovascular events. After adjustment for age and sex, each additional 0.1 mm of albumin-corrected calcium at baseline was associated with a hazard ratio (HR) of 1.09 [95% confidence interval (CI) 0.99, 1.20; P = 0.062] for total mortality, 1.06 (95% CI 0.92, 1.23; P = 0.41) for cardiovascular mortality and 1.13 (95% CI 1.03, 1.24; P = 0.012) for cardiovascular events. These associations were attenuated by further adjustment for standard cardiovascular risk factors with HR 1.03 (95% CI 0.94, 1.14), 0.99 (95% CI 0.86, 1.16) and 1.05 (95% CI 0.95, 1.15), respectively. CONCLUSION: After adjustment for age and sex, plasma calcium is a predictor of cardiovascular events. This appears to be mediated by conventional cardiovascular risk factors, and calcium is not an independent predictor of cardiovascular disease.

Impact of voluntary folate fortification on plasma homocysteine and serum folate in Australia from 1995 to 2001: a population based cohort study.

STUDY OBJECTIVE: To investigate the effect of the voluntary folate fortification policy in Australia on serum folate and total plasma homocysteine (tHcy) concentrations. DESIGN: Population based cohort study. SETTING: Perth, Western Australia. PARTICIPANTS: Men and women aged 27 to 77 years (n = 468), who were originally randomly selected from the Perth electoral roll. The cohort was surveyed in 1995/96 before widespread introduction of folate fortification of a variety of foods, and followed up on two occasions, firstly in 1998/99 and again in 2001, when a moderate number of folate fortified foods were available. Subjects with abnormal serum creatinine concentrations at baseline were excluded from this analysis. MAIN RESULTS: Repeated measures analysis of variance was used to determine changes in serum folate and tHcy over the three surveys and to assess whether time trends were related to age, sex, MTHFR C677T genotype, or consumption of folate fortified foods. An increase (38%) in mean serum folate (p < 0.0005) and a decrease (21%) in mean tHcy (p < 0.0005) were seen after introduction of the voluntary folate fortification policy in Australia. Serum folate was consistently higher (p = 0.032) and tHcy was consistently lower (p = 0.001) in subjects who consumed at least one folate fortified food compared with subjects who did not consume any folate fortified foods in the previous week. The time related changes in serum folate and tHcy were affected only by intake of folate fortified foods (p < 0.0005) and not by any other measured variables including age, sex, or MTHFR genotype. CONCLUSION: Voluntary fortification of foods with folate in Australia has been followed by a substantial increase in serum folate and decrease in tHcy in the general population.