Research paper. The relationship between socioeconomic status and ‘hardcore’ smoking over time - greater accumulation of hardened smokers in low-SES than high-SES smokers.

OBJECTIVES: This paper used national survey data to investigate 'hardcore' smoking as predicted by the 'hardening hypothesis', and to examine the relationship between 'hardcore' smoking and socioeconomic status (SES). METHODS: Analyses were performed using data from four waves of the Australian National Drug Strategy Household Survey between 2001 and 2010, a large national survey with a sample size of approximately 24 000 participants per wave. The primary outcome variable was 'hardcore' smoking, comprised of the variables: 'no quit attempt in past 12 months'; 'no plan to quit'; and smoking more than 15 cigarettes per day. The main predictor variables used were SES assessed by the Socio-Economic Indexes for Areas (SEIFA), and survey wave. Other sociodemographic variables were also examined. RESULTS: Overall, 'hardcore' smoking remained stable from 2001 to 2010. However, 'hardcore' smoking declined among high-SES smokers (from 1.8% to 1.0%), but not among low-SES smokers (around 3.4%). 'Hardcore' smoking was strongly associated with SEIFA quintile (p<0.001). There was a significant interaction effect between top and bottom SEIFA quintiles and wave (p=0.025), with a decline in 'hardcore' smoking measures over the four waves among those in the top two SEIFA quintiles, with odds in 2010 of 0.39 (95% CI 0.17 to 0.87; p=0.012), down from 0.64 (95% CI 0.50 to 0.82; p<0.001) in 2001, while 'hardcore' smoking remained stable among those in the bottom two SEIFA quintiles. CONCLUSIONS: The results from high SES smokers suggest 'hardcore' smokers are able to quit, but outcomes among low-SES smokers are less encouraging. [ABSTRACT FROM AUTHOR]