Seeking truth in heroin indicators: the case of New York City

An epidemiological investigation of New York City's indirect indicators of heroin activity from 1970 through 1976 yielded insights about New York City heroin trends. Indirect indicators were gathered from official data sources, such as law enforcement, health, and treatment agencies. Since each indicator had significant limitations inhibiting interpretation, a factor analysis of the indicators was performed, resulting in the reduction of a large number of variables to a small number of factors. The factor analysis demonstrated the way in which New York City indicators cluster or move together--a "street" component, including arrests, hepatitis, price and purity of retail heroin; a "new admissions to methadone treatment" component; and a "readmissions to methadone treatment" component. Furthermore, the analysis revealed the time-lag relationships between components--"new admissions to methadone treatment" lag 1--2 years behind the "street" component; "readmissions to methadone treatment" lag 1--3 years behind the "new admissions" component. Finally, the 1970--1976 factor scores were related to 1970--1974 estimates of narcotic addicts in New York City in regression analysis, and were also projected through 1978, yielding estimates of New York City's heroin addict population from 1975 through 1978.