Discussion
The aim of this study was to investigate predictors of outcome in
ICBT and IBSM for severe health anxiety. A replication design was
used enabling a hypothesis driven approach guided by previous
predictor findings in ICBT for severe health anxiety (Hedman et al.,
2011). As expected, baseline health anxiety predicted larger improvements
but higher levels of end state health anxiety, while
treatment adherence in terms of number of completed modules
significantly predicted larger improvement and less health anxiety
after treatment. Analyses with linear multiple regression and
quantile regression produced largely the same results. Contrary to
our hypothesis, depressive symptoms were unrelated to both
improvement as well as end state health anxiety. There were no
significant moderators in the final regression models and exploratory
analyses showed that treatment credibility and working
alliance significantly predicted outcome.
The general conclusion from the present study is that when
making treatment recommendations, there are two stable factors
that are related to how successful therapy will be, namely baseline
health anxiety and treatment adherence. Participants with more
health anxiety are likely to make larger improvements, but also to
have higher symptom levels after treatment. This indicates that
exposure-based ICBT and IBSM are suitable treatments for patients
with severe symptoms but that they will have more health anxiety
after treatment compared with patients with lower levels of baseline
health anxiety. These results are in line with previous findings of
studies investigating predictors of face-to-face CBT for severe health
anxiety Buwalda and Bouman (2008). The second stable predictor,
treatment adherence, is of high importance as it indicates that it is
central that the patient actually goes through the treatment steps as
planned. The clinician should make efforts to monitor adherence
and provide additional guidance and prompts to patients who do
not complete modules in the pace prescribed by the treatment. An
interesting venue for future research is to investigate whether
additional treatment for these patients, such as addition of scheduled
telephone appointments, can increase the proportion of participants
in remission at post-treatment. In a recently conducted
randomized trial we found that adding a booster intervention after
treatment can yield significantly better outcomes in ICBT for
obsessive-compulsive disorder suggesting that increasing the dose
of therapy may be beneficial in ICBT (Andersson et al., 2014).