To The Editor: In our trial on the efficacy of brief early CBT, exploratory subgroup analyses showed that CBT led to higher reductions in symptoms of PTSD subjects relative to waiting list comparison subjects when offered to patients who were included within the first month after a traumatic incident than when offered to those patients who were included 1 to 3 months after a traumatic event. In our trial, early-inclusion patients who received no treatment (waiting list comparison patients) showed a significantly worse symptom course than early-inclusion CBT patients. Therefore, Dr. Scheeringa’s suggestion that this effect can be explained by a higher natural recovery in the early-inclusion group may be rejected. In fact, 4-month follow-up PTSD scores were even higher in the early-inclusion waiting list comparison patients than in later-inclusion waiting list comparison patients.
The other issue on which Dr. Scheeringa comments is the sentence in our discussion section in which we concluded that our results further supported recommendations in two recently developed practice guidelines that for patients with a severe initial traumatic response, brief trauma-focused CBT may speed recovery and prevent PTSD if treatment begins 2 to 3 weeks after trauma exposure (1, 2). We believe that our results supported this recommendation, since we not only found early CBT to be more efficacious than late CBT, but also that CBT was more efficacious in patients with a comorbid major depression, which may indicate a more severe posttraumatic response.
Finally, as in our article, we would like to reemphasize that these results stem from exploratory subgroup analysis, which means that they should be interpreted with restraint. At best, they should tempt researchers to design new studies to test the hypotheses derived from these analyses, but they should not lead to changes in clinical practice (3).
1.National Institute for Clinical Excellence (NICE). Post-traumatic stress disorder; the management of PTSD in adults and children in primary and secondary care. Gaskell and the British Psychological Society. http://www.nice.org.uk/page.aspx?o=248114; 2005
2.Ursano RJ, Bell C, Eth S, Friedman M, Norwood A, Pfefferbaum B, et al. Practice guideline for the treatment of patients with acute stress disorder and posttraumatic stress disorder. Am J Psychiatry 2004; 161(suppl 11):3–31
3.Assmann SF, Pocock SJ, Enos LE, Kasten LE. Subgroup analysis and other (mis)uses of baseline data in clinical trials. Lancet 2000; 355:1064–1069
The authors’ disclosures accompany their original article.
This letter (doi: 10.1176/appi.ajp.2007.07030406r) was accepted for publication in April 2007.