The AusD Study: A Population-based Study of the Determinants of Serum 25-Hydroxyvitamin D Concentration Across a Broad Latitude Range

Abstract

Observational studies suggest that people with a high serum 25-hydroxyvitamin D (25(OH)D) concentration may have reduced risk of chronic diseases such as osteoporosis, multiple sclerosis, type 1 diabetes, cardiovascular disease, and some cancers. The AusD Study (A Quantitative Assessment of Solar UV Exposure for Vitamin D Synthesis in Australian Adults) was conducted to clarify the relationships between ultraviolet (UV) radiation exposure, dietary intake of vitamin D, and serum 25(OH)D concentration among Australian adults residing in Townsville (19.3°S), Brisbane (27.5°S), Canberra (35.3°S), and Hobart (42.8°S). Participants aged 18-75 years were recruited from the Australian Electoral Roll between 2009 and 2010. Measurements were made of height, weight, waist:hip ratio, skin, hair, and eye color, blood pressure, and grip strength. Participants completed a questionnaire on sun exposure and vitamin D intake, together with 10 days of personal UV dosimetry and an associated sun-exposure and physical-activity diary that was temporally linked to a blood test for measurement of 25(OH)D concentration. Ambient solar UV radiation was also monitored at all study sites. We collected comprehensive, high-quality data from 1,002 participants (459 males, 543 females) assessed simultaneously across a range of latitudes and through all seasons. Here we describe the scientific and methodological issues considered in designing the AusD Study.

Weekend personal ultraviolet radiation exposure in four cities in Australia: Influence of temperature, humidity and ambient ultraviolet radiation

“…This analysis uses data from the multi-centre AusD Study [4], the primary aim of which was to examine determinants of vitamin D status in adults (aged 18 + years) resident in four eastern Australian cities, each separated by approximately 8°of latitude: Townsville (19°S, 146°E), Brisbane (27°S, 153°E), Canberra (35°S, 149°E) and Hobart (43°S, 147°E). The latitude range of the study regions provided wide variation in ambient UVR levels and other meteorological factors, and standardised data collection across the four regions ensured comparable measurement of sun exposure behaviours.…”

“…The methods of the AusD Study have been described elsewhere [4]. In brief, 1002 adults aged 18-75 years were recruited from the Australian Electoral Roll between May 2009 and December 2010, approximately equally distributed by sex, age group and study region.…”

“…with 9 options), and parents' ethnicity (using the question ''What is your mother's/father's ethnic origin (that is, the place where the most of their ancestors came from)?'' with 20 possible options) [4].…”

“…Daily use of sunscreen was recorded (yes/no) using the question ''Did you apply any sunscreen today?'' [4]. On each of the 10 days that they were completing diaries, participants were asked to wear a polysulphone dosimeter [18] on a wristband from the time they woke up in the morning until they went to bed at night, to measure daily personal UVR exposure.…”

“…The general characteristics of the study participants have been described elsewhere [4]. In summary, 80% of all participants were born in Australia and 54% were female.…”