National estimates of Australian gambling prevalence: Findings from a dual-frame omnibus survey

Background, aims and design: The increase in mobile telephone-only households may be a source of bias for traditional landline gambling prevalence surveys. Aims were to: (1) identify Australian gambling participation and problem gambling prevalence using a dual-frame (50% landline and 50% mobile telephone) computer-assisted telephone interviewing methodology; (2) explore the predictors of sample frame and telephone status; and (3) explore the degree to which sample frame and telephone status moderate the relationships between respondent characteristics and problem gambling. Setting and participants: A total of 2000 adult respondents residing in Australia were interviewed from March to April 2013. Measurements: Participation in multiple gambling activities and Problem Gambling Severity Index (PGSI). Findings: Estimates were: gambling participation [63.9%, 95% confidence interval (CI)=61.4-66.3], problem gambling (0.4%, 95% CI=0.2-0.8), moderate-risk gambling (1.9%, 95% CI=1.3-2.6) and low-risk gambling (3.0%, 95% CI=2.2-4.0). Relative to the landline frame, the mobile frame was more likely to gamble on horse/greyhound races [odds ratio (OR)=1.4], casino table games (OR=5.0), sporting events (OR=2.2), private games (OR=1.9) and the internet (OR=6.5); less likely to gamble on lotteries (OR=0.6); and more likely to gamble on five or more activities (OR=2.4), display problem gambling (OR=6.4) and endorse PGSI items (OR=2.4-6.1). Only casino table gambling (OR=2.9) and internet gambling (OR=3.5) independently predicted mobile frame membership. Telephone status (landline frame versus mobile dual users and mobile-only users) displayed similar findings. Finally, sample frame and/or telephone status moderated the relationship between gender, relationship status, health and problem gambling (OR=2.9-7.6). Conclusion: Given expected future increases in the mobile telephone-only population, best practice in population gambling research should use dual frame sampling methodologies (at least 50% landline and 50% mobile telephone) for telephone interviewing.