Personality disorders and the persistence of anxiety disorders: evidence of a time-of-measurement effect in NESARC.

Recent studies using data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) have found that some personality disorders (PDs) increase the persistence of several Axis I disorders. However, these effects are potentially confounded with the data collection wave in which PDs were assessed. Our aim was to extend published analyses to the case of anxiety disorders and to determine the robustness of the associations to analyses examining time-of-measurement effects. Persistence of anxiety disorders was defined either as follow-up diagnosis among participants diagnosed at baseline ("prediction") or baseline diagnosis among participants diagnosed at follow-up ("post-diction"). Results revealed a robust pattern of higher odds ratios for post-diction among PDs assessed at baseline, and lower odds ratios for post-diction among PDs assessed at follow-up, suggesting a time of measurement artifact. Although only 4% of associations were robust to both predictive and post-dictive analyses, these were consistent with previous research.