Prevalence of excessive gambling before and after introduction of a national lottery in the United Kingdom: another example of the single distribution theory

Background. According to the single distribution theory advocated by Rose, the prevalence of a deviant condition such as excessive alcohol consumption depends upon the average level of the corresponding characteristic in the population. The objective of this study was to establish whether the single distribution theory applies to gambling behaviour Methods. Household gambl ing expenditure in the United Kingdom was Examined using Family Expenditure Survey data collected before and after the introduction of a national lott ery in November 1994. Results. In cross-sectional analyses, the mean (or me dian) household expenditure on gambling for each region predicted the preva lence of excessive gambling in that region: the slope of the relationship i n 1995-96 was equivalent to an increase of 1.2 (95% CI 0.7-1.7) points in t he percentage of households gambling more than 10% of income for every incr ease of pound 1 in mean household gambling expenditure. The introduction of the national lottery was associated with an increase in mean household gam bling Expenditure from pound 1.45 to pound 3.81 per week, and an increase i n the proportion of households gambling more than 10% of total income four- fold from 0.4% to 1.7%. Among households with income of less than pound 200 /week, the proportion gambling more than 10% of their income increased from 0.6% to 3.2%. Interpretation. The single distribution theory applies to ga mbling behaviour. The increase in average gambling expenditure associated w ith the introduction of a national lottery in the United Kingdom has led to a pronounced increase in the prevalence of excessive gambling, especially in low-income households. This is likely to increase the prevalence of gamb ling disorders and to exacerbate serial inequalities in health.