A Reply to Gambino's "An Epidemiologic Note on Verification Bias: Implications for Estimation of Rates"

Treatment of Pathological Gambling Using a Guided Self-Change Approach

Pathological gamblers are prone to leave treatment early and often display low levels of motivation within treatment. Use of brief treatments that emphasize reducing client ambivalence through motivational techniques may help increase the likelihood of treatment compliance. This case study describes a 5-session treatment of pathological gambling using a brief and motivationally focused cognitive—behavioral guided self-change (GSC) approach. The 36-year-old gambler in this study was treated for pathological gambling. At 1-month and 6-month follow-ups, the individual evidenced significant improvement in symptoms of pathological gambling. The client also showed considerable reductions in gambling behaviors including number of gambling episodes, length of time spent gambling, and amount of money wagered. These results support use of the GSC approach in treating pathological gamblers.

Prevalence of pathological gambling in Switzerland after the opening of casinos and the introduction of new preventive legislation

OBJECTIVE

This survey aimed to evaluate the prevalence of pathological gambling (PG) in the Swiss population in 2005 and the link between PG and alcohol abuse. This replication study made it possible to compare the prevalence rates of PG measured before and after the introduction of casinos and new preventive legislation.

METHOD

A total of 2803 telephone interviews were completed using standardized assessment instruments for identifying gamblers (South Oaks Gambling Screen) and alcohol abuse (CAGE).

RESULTS

The past-year prevalence rates were 0.8% for problem and 0.5% for PG. No relationship was found between alcohol abuse and gambling behaviour. The past-year prevalence of disordered gambling did not change between 1998 and 2005.

CONCLUSION

Despite widespread openings of casinos in Switzerland since 2002, the prevalence estimates of past-year disordered gambling have remained stable. The discussion focuses on different factors (social measures, legal obligations and social adaptational capacities) that may account for the stabilization of prevalence estimates.

Interpreting prevalence estimates of pathological gambling: Implications for policy

Some guidelines for interpreting prevalence estimates for the purpose of establishing the number of pathological gamblers in the community are presented. The analysis is based on the concept of the likelihood ratio, a recommended procedure for validating criteria for defining cases based on test scores. It is shown that the likelihood ratio can be employed with available estimates of prevalence to translate cut-off scores into positive predictive value. Those cut-off scores associated with high positive predictive values provide an empirical measure of confidence that those gamblers who meet or exceed the cut-off criterion are pathological gamblers. A potential limitation of the analysis is the possible specificity of results to the validation studies employed to compute likelihood ratios and to the specific estimates of prevalence used to determine positive predictive value. A recommendation is presented for obtaining study- or community-specific validation evidence.

Estimating Confidence Intervals and Sampling Proportions in Two-Stage Prevalence Designs

In response to Abbott and Volberg's (in press) rejoinder to my epidemiologic note on verification bias and estimation of prevalence rates (Gambino, in press), I provide the formulas for computing confidence intervals for the results of second-stage verification. In addition, I provide the appropriate equation for determining confidence intervals when prevalence is near zero or one. Finally, we present formulas for determining the most efficient sample sizes needed to minimize second-stage variance estimates. These allow the investigator working under a fixed budget to determine the relative value of sampling negative screens to test for false negatives. We close with an observation on the interpretability of evidence.