RESUMO
PURPOSE: This study provides a unique application of a procedure to link anonymous survey records as a means to assess mental health problems among soldiers after return from deployment to Iraq. The research purpose is to validate the use of a linkage method on anonymous survey data for longitudinal analysis. METHODS: This research analyzes surveys completed by soldiers at three (N = 4,903), six (N = 3,110), and 12 (N = 2,544) months post-Operation Iraqi Freedom (OIF) deployment. To protect anonymity while also allowing for longitudinal analysis, the survey includes four self-generated codes for matching the surveys from individual soldiers. The surveys were linked using Link Plus (Centers for Disease Control and Prevention, Atlanta, GA). Three matched groups (3-6 months, 6-12 months, and 3-12 months) were created, matching on the anonymous codes and demographic variables. An internal validation of the linkage results was performed and selection bias was assessed. RESULTS: The matched records showed very high agreement in variables not included in the matching procedure and were similar to the unmatched records with regard to demographics and post-traumatic stress disorder (PTSD) prevalence. CONCLUSIONS: The use of self-generated codes protects anonymity while the method utilized and validated in this paper allows for longitudinal data analysis. The results support an absence of any notable selection bias.
