Prevalence is an epidemiological snapshot that reflects the frequency of disease for a particular period of time. This is why epidemiologists sometimes refer to it as point prevalence. Since it is static measure, a single prevalence estimate cannot be used to demonstrate change over time [see WAGER 4(30)].
Replication studies try to overcome this limitation by combining a series of prevalence estimates. Thus, the story told by Ladouceur and his colleagues in their 1989 Quebec prevalence study1 (1991) was enhanced by the results of their follow-up study 2 (1999) conducted in 1996.
The figures at left show the changes in the Quebecois gambling landscape between 1989 and 1996. Most notable in the social landscape are the increases in lottery validation terminals, the introduction of video lottery terminals (VLTs), and the opening of three casinos. Using the SOGS, lifetime estimates of problem gambling increased from 2.1% to 2.4% over the seven-year period. Lifetime estimates of pathological gambling increased from 1.2% in 1989 (CI: 0.7%, 2.1%) to 2.1% in 1996 (CI: 1.4%, 3.0%). However, the difference in prevalence between 1989 and 1996 is not statistically significant.
It is interesting to note, however, that the mean onset of gambling behavior increased significantly from 20.68 years in 1989 to 23.46 years in 1996 (F=44.46, df=1, p<.0001). Furthermore, the proportion of problem gamblers receiving help for gambling behavior decreased from 11.4% to 6.2%.
At first glance, these latter two findings seem counterintuitive. The increase in age of onset might be due to the fact that as gambling becomes more accessible, people are becoming more aware of its potential hazards. As a result, parents might be preventing their children from gambling, resulting in the observed increase in the age of onset for gambling behavior. Future research could attempt to explain these apparent paradoxes.
References
Ladouceur, R. (1991). Prevalence estimates of pathological gambling in Quebec. Canadian Journal of Psychiatry,36,732-734.
Ladouceur, R., Jacques, C., Ferland, F., & Giroux, I. (1999). Prevalence of problem gambling: A replication study 7 years later . Canadian Journal of Psychiatry, 44, 802-804.