Methods: Participants were 590 individuals 18 years or older in court-mandated outpatient drug diversion programs in Southern California. Participants took the baseline survey at the drug diversion facility and took the 1 year follow-up at a drug diversion facility or a location nearby. General linear model regressions were conducted and controlled for condom use at baseline.
Results: Results confirmed that the SIIS for condom use predicted condom use one year later (p < 0.05) and accounted for 9.66% of the variance (entire model accounted for 32.41%), even after controlling for condom use at baseline. However, the relationship between the SIIS and condom use one year later was not moderated by behavioral intentions to use condoms, alcohol use before or during sex, or amphetamine use before or during sex (p > 0.05).
Conclusions: The present study is the first known study to identify the predictive validity of any type of implementation intention assessment over an extended period of time. The significant predictions for condom use provide support for the future use of the SIIS for condom use as a fidelity check or mediator for interventions utilizing implementation intentions to increase condom use. These findings, coupled with the ability of the SIIS to detect intervention effects (Nydegger et al., 2013), imply that it can be used as an outcome measure in situations where a follow-up behavior is not feasible, such as drug diversion programs. Future research should examine various diverse populations to ensure the predictive validity, reliability, generalizability of SIIS, and tailor the SIIS to other health behaviors.