There were several limitations to the data used in these analyses. The samples may not be representative of all drug users in the two locations. This may especially be the case for the NY sample; individuals who are migrants may be difficult to locate for participation in research projects.17
In terms of visits to the other airbridge location, only data for the prior 3 years were collected, and this limitation on the time period may have influenced the relationships identified. Despite these limitations, several conclusions emerged from the analysis.
Overall, ongoing airbridge mobility appears relatively low among this sample. Moves to the current location (NY or PR) generally occurred many years ago, about 15 years. Although almost two-thirds of the NY sample had lived in PR at some point in their lives, recent visits to the other airbridge location were not frequent; in the last 3 years, less than 10% of the participants in each site visited the other location. Among those who made overnight trips, about twice as many participants, for both sites, went to other locations in the U.S.
The reasons given for their most recent move to NY or PR varied, with family-related reasons being the most frequent for participants in both locations. This importance of the family indicates that efforts to engage families, as an important source for development of social support for reductions in drug use and HIV risks, may be a helpful strategy. In both sites, seeking employment or education, or attempts at getting away from drugs, were the reasons for moves for at least 15% of the sample. This indicates a potential opportunity in providing assistance for prosocial activities for drug users who may recently arrive in NY or PR. Efforts to engage them in services at this point, when motivations for change may be high, have the potential for positive behavior change. It is also interesting to note that although moving to obtain health or social services was not reported by a large percentage of participants, it was much more likely to be a reason for moving from PR to NY than from NY to PR, heightening the opportunities that may be provided by efforts to extend services to migrants in NY.
The examination of the relationship between mobility and risk indicated several important findings. For those IDUs recruited in NY, if they had used drugs regularly in PR before coming to NY, they were more likely to be risky in IDU behaviors, as previously reported.3
This finding is likely related to the reduced access to risk reduction services in PR (e.g., drug treatment and needle exchange), resulting in riskier behaviors (evidenced when they migrate to NY). For those recruited in PR, having used drugs in NY was not related to risk in PR; although the risk reduction service network is greater in NY, because tools for risk reduction are not available in PR, lower-risk behaviors may be difficult to maintain.
Taking recent overnight trips was not related to risks, although, in both locations, it was related to greater likelihood for recently engaging in sex. Those who are more likely to travel thus should be targeted for enhanced sexual-risk reduction/condom-promotion efforts.
The multivariate analyses indicated that demographic variables also played a role in risk levels. Younger IDUs, in particular, should be targeted for risk reduction, especially given reports of high HCV seroconversion early in injection careers.18
The total number of moves was related to higher risk, indicating that the results of frequent relocations may merit further study as a factor in risk behaviors. The impact of HIV status seemed to operate differently in the two locations, associated with a reduced risk in NY and a higher risk in PR, especially in terms of sharing injection equipment. This also requires further study and may be related to the lack of access to sufficient services in PR. Finally, as indicated in prior studies, the higher risk behaviors found in PR should be addressed through the enhancement of drug treatment, access to clean needles, and other related health and social service programs. This is particularly important given the cohort effect found in PR, in that those recruited in cohort 2 (recruited about 4 years later) reported higher sharing behaviors. Ongoing surveillance is needed to determine if this disturbing finding indicates an increasing trend toward greater risk among injectors in PR. This is particularly important to investigate given the declines in drug treatment services in PR from 1998 to 2002.19