The results of our study suggest that while mental health services did not increase substantially in the 12-month postdisaster period, they did increase somewhat 24 months after the WTCD. This was especially true for use of psychotropic medications (). Conversely, use of medical doctors for mental health support appeared to decrease 24 months after the WTCD. In terms of comparative effectiveness, brief interventions appeared to be superior to conventional psychotherapy interventions. Using robust propensity score matching to assess brief and multisession therapeutic interventions, respectively, indicated that multisession interventions had poorer outcomes. Of course, a key question is could these findings be confounded by indication?
Confounding by indication is a type of selection bias, whereby those who receive a certain treatment might be more ill than those who did not receive that treatment (Grobbee and Hoes, 1997
). In clinical effectiveness research, the randomized controlled trial is considered the ideal design, since it enables many sources of bias to be removed from the observed outcomes (Grobbee and Hoes, 1997
; Hulley et al., 2007
). In observational studies, allocation to treatment is not random. This means that the prognoses of the patient groups studied may not be comparable. Propensity methods were developed to specifically address this problem (Boscarino et al., 2006
). In the current study, we used 1:5 matching, with 1 intervention case matched to 5 nonintervention controls. We used an optimal matching method, whereby the smallest distance between all possible pairs was selected. For propensity matching, as suggested, we first used the pscore program in Stata to assess the adequacy of propensity matching. For our final matching algorithm, we used the nnmatch program, which includes additional bias correction adjustments.
It has been noted that while confounding by indication can create problems in assessing treatment effects in nonexperimental studies, these problems are not insurmountable (Guo and Fraser, 2010
; Rubin, 2006
). Valid inferences can be drawn when the residual dissimilarities in patients receiving treatments can be accounted for or adjusted (Grobbee and Hoes, 1997
; Guo and Fraser, 2010
; Rubin, 2006
). Thus, the effect of confounding can be removed by measuring patient characteristics that formed the basis of this confounding and then by matching for these in the analyses. In the current study, information related to potential confounding was comprehensive. Consequently, the rate/severity of baseline disorders in the treated versus untreated patients was more likely similar. In addition, 2 treatment interventions were compared (e.g., brief vs. conventional treatments) using the same propensity methods. As shown, the brief intervention group exhibited improvement, while the conventional intervention group did not.
Observations drawn from this study, of course, should be interpreted with some caution. We used self-reported data collected by telephone among adult householders, raising the possibility of respondent recall and selection bias. In addition, we surveyed only those who spoke either English or Spanish. However, it is noteworthy that while the differences found for the brief intervention group were not always large, they were consistent and multifaceted. As was seen, these included reductions in PTSD symptoms, major depression, depression symptoms, alcohol dependence, and anxiety disorder at follow-up. Conversely, the results for the psychotherapeutic intervention group were generally worse in these same clinical domains, suggesting that those who received brief interventions benefited as many as 2 years after the WTCD, while those receiving conventional therapy did not.
Postdisaster crisis interventions have been in used in the past. However, the effectiveness and safety of these interventions have been debated (Gist and Devilly, 2002
; Roberts et al., 2009
; van Emmerik et al., 2002
). Our research suggests that emergency mental health services may be associated with better outcomes up to 2 years after a disaster. It is important to stress that this study does not suggest that brief, single-session interventions are effective (van Emmerik et al., 2002
). Rather, it suggests that brief mental health interventions conducted by professionals at the worksite, community center, and other places may be effective following a large-scale traumatic event. However, as noted elsewhere, the reasons for this association are unclear (Boscarino et al., 2005
), but may be due to indirect effects, such as later treatment-seeking or by facilitating professional referrals, or by some other indirect treatment effect.
These findings will require replication. A question to be addressed in future research will relate to the effectiveness of brief interventions versus conventional therapy. In particular, it needs to be determined if the differences found are due to residual confounding, such as by selection bias, whereby sicker patients received conventional therapy, or to the iatrogenic effects of receiving delayed, less focused treatments after a traumatic event. Given our results and recent reports stressing the need for additional comparative effectiveness studies (Committee on Comparative Effectiveness Research, 2009
), it would be unwise to ignore these findings. Since this research is based on an observational study, it is tempting to suggest that the results are confounded. For example, it is still possible that our results are biased by some unmeasured variable, a limitation with all observational research (Boscarino et al., 2006
). However, recent research suggests that early post-trauma interventions may be more effective in eliminating longer-term stress disorders by preventing memory consolidation and accelerating fear extinction (Schiller et al., 2010
). Delayed interventions may not have this same impact. Biologically, it is plausible that early interventions may prevent consolidation of fear conditioning and stimulus generalization simply by enhancing better sleep (Lavie, 2001
). PTSD is linked to heighted arousal and sleep disturbances, symptoms that define the core syndromes of this disorder. If the latter is correct, then this could, in part, explain the findings reported for brief interventions. Further research is recommended.
Finally, it is important to emphasize that because Project Liberty was available during our study period, which promoted the availability of free crisis counseling, this factor may have affected our results. It is unusual for this type of federally funded mental health care to be made widely available (Felton, 2002
). However, as previously suggested, for some reason Project Liberty failed to have a major impact on service use among community-based NYC adults (American Psychiatric Association, 2002
; Boscarino et al., 2004
). As demonstrated in the current study, there was no huge surge in mental health service use in NYC among community-based adults during Project Liberty. Furthermore, during our follow-up survey we asked respondents, specifically, if they “…ever had any contact with or received any services from Project Liberty.” Less than 5% of NYC adults said that they did have contact with or received services from this program. Thus, while this low percentage could be partly due to recall bias and/or to the ineffective marketing of the Project Liberty “brand name,” it does not appear that the Project Liberty intervention had a major impact on our study population. Alternative explanations and further research are required.