Holden et al. BMC Public Health 2010, 10:96 http://www.biomedcentral.com/1471-2458/10/96 report significantly higher rates of ED [8]. It has therefore been proposed that the assessment of erectile function may provide a useful indicator for earlier detection and treat- ment of other life-threatening conditions [9]. Indeed, the association between obesity and ED has recently been explored with sexual function being improved in a propor- tion of obese men after lifestyle changes to reduce total body weight [10]. However, the relationship between other reproductive health disorders and a range of behavioural and biomedical determinants is less clear. Limitations exist in the comparison of studies that focus on individual reproductive health disorders in iso- lation due to methodological differences, particularly due to sampling from different populations and different definitions used in the reporting of prevalence rates. This national, population-based cross-sectional study explored a range of behavioural and biomedical factors and their association with reproductive health disorders in a representative sample of Australian men aged 40 years and over. By investigating a range of reproductive health disorders within the same population of men, commonality between health conditions and health determinants can be more clearly identified. Methods The MATeS study has been described previously [4]. In summary, between September and December 2003, computer-assisted telephone interviews (CATIs) of a representative sample of men from across Australia, aged 40 years and over, were undertaken. Within each State and Territory, respondents were stratified into four age groups: 40-49 years, 50-59 years, 60-69 years and 70+ years. Sampling continued until a minimum of 1250 men in each age stratum had been surveyed. Respondents were recruited from across all States and Territories in Australia by random selection of house- holds from the electronic telephone directory (Electronic White Pages, EWP), with over sampling in some age brackets and geographical regions to ensure proportion- ate representation. Information was sent to households describing what was required of participants to be in the study and the inclusion criteria. The interviewer phoned the households and asked potential participants if they were willing to be interviewed. An affirmative response to participation was taken as consent. An overall indivi- dual response rate of 78% was achieved. Socio-demo- graphic characteristics of the men participating in the study were generally representative of the Australian population [4]. The study was approved by the Southern Health Human Research Ethics Committee, Melbourne. Telephone survey instrument The telephone survey instrument included more than 90 questions focusing on socio-demographic issues Page 2 of 9 (age, marital status, ethnicity, occupation and educa- tion), general health and lifestyle, sexual function, ferti- lity, contraception, relationship issues, and knowledge, attitudes and beliefs concerning male reproductive health and its disorders. The survey took 17.5 minutes, on average, to complete. Men in the youngest age group completed interviews in a shorter average time than those in the oldest age group (16.4 and 18.5 min- utes, respectively). The full CATI is available at http:// www.andrologyaustralia.org/docs/Methods_Manual_- CATI.pdf Outcomes All information obtained from the interview was self- report with no check against medical records. Where available, questions from other validated instruments and those used in an Australian context were incorpo- rated. Using the Massachusetts Male Aging Study (MMAS) single question [11], erectile dysfunction was defined as ‘sometimes’ (moderate) or ‘never’ (severe) being able to get and keep an erection that is rigid enough for satisfactory sexual activity. LUTS were assessed using the International Prostate Symptom Score (IPSS) and defined as absent or mild (score ≤ 7), moderate (score 8-19), or severe (score 20-35) [12]. A self-reported diagnosis of prostate disease (PD) was indi- cated if the respondent noted that a doctor had ever told them they had a prostate problem. The question ‘Do you think you may currently be suffering from low levels of testosterone now?’ was included to assess men’s perception of whether they suffer from symptoms of androgen deficiency. A positive response was coded as ‘perceived symptoms’ of androgen deficiency (pAD). Self-reports of specific diseases were noted when men reported receiving a specific diagnosis or prescribed medication by a doctor. Exposures Exposure variables were all self-reported including height, weight and waist circumference. Self-reported waist circumference has been shown to have reasonable validity and self-reported weight to be highly correlated with measured weight [13]. Lifestyle factors Body Mass Index (BMI) was classified as underweight (<20 kg/m2); acceptable (20.0-24.9 kg/m2); overweight (25.0-29.9 kg/m2); and obese (≥ 30 kg/m2). Waist cir- cumference was classified as small (<94.0 cm); medium (94.0-101.9 cm); and large (≥ 102 cm) [14]. Cigarette (or other tobacco product) smoking, alcohol consumption and physical activity (assessed by recall of intensity, fre- quency and type in the last week) were classified accord- ing to Australian guidelines [15-17]. The categories are described in Table 1.