Untreated hypertension among Australian adults: the 1999-2000 Australian Diabetes, Obesity and Lifestyle Study (AusDiab)

Objective: To measure the prevalence of untreated hypertension in Australian adults, and examine the associations with clinical and lifestyle factors. Design: AusDiab, a cross-sectional survey conducted between May 1999 and December 2000, involved participants from 42 randomly selected census districts throughout Australia. Participants: Of 20 347 eligible people aged greater than or equal to 25 years who completed a household interview, 11247 attended a physical examination (response rate, 55%). Main outcome measures: The prevalence of hypertension (blood pressure greater than or equal to 140/ 90 mmHg or self-reported use of anti hypertensive drugs) and its treatment; associations of clinical and lifestyle factors with the treatment of hypertension; and adequacy of treatment for primary and secondary prevention of cardiovascular disease. Results: The prevalence of hypertension was 28.6 per 100 (95% Cl, 25.0-32.3), and the prevalence of untreated hypertension was 15.2 per 100 (95% Cl, 13.2-17.2). Of those with untreated hypertension, 80.8% (95% Cl, 74.7%-85.0%) had had a blood pressure check within the preceding 12 months. At least one modifiable lifestyle factor was present in 71.7% (95% Cl, 68.5%-74.8%) of participants with untreated hypertension. Although lower risk clinical characteristics of younger age and lack of hyperlipidaemia were independently associated with untreated hypertension, 53.5% warranted treatment based on current cardiovascular disease prevention guidelines and multivariable absolute risk assessment. Conclusions: Considerable scope remains for reducing the burden of cardiovascular disease through lifestyle modification and rational treatment of hypertension.