Journal of Rehabilitation Medicine 51-4inkOmslag | Page 37

Impact of PiD on outcome after TBI and aSAH
Strengths and limitations of study
To the best of our knowledge, this is the first study to
explore the potential effects of pituitary dysfunction on
clinical outcome after TBI or aSAH by use of systema-
tic measurements of hormone levels at 4 time-points
during the first year after the event and by cognitive as-
sessment with BNIS and global measures, while most
previous studies used only global measures, most often
GOS or GOSE. Study participants were all managed at
the same NICU and with the same, structured follow-
up, which should reduce confounding regarding acute
and later interventions, but also limits generalizability.
Similarly, all clinical assessments were performed by
the same person (AT), which should strengthen the
reliability of assessment data, but also bears a risk for
systemic bias of scoring. However, we consider this
risk low, as most assessments are highly standardized.
Due to sample size and small subgroups of patients,
power issues must be considered. Thus, there is a risk
that some associations were not detected due to type
II errors. Although adherence was fairly good for this
kind of longitudinal study, the presence of drops-outs
and missing data carries a risk of underestimation of
pituitary dysfunction in our study. IGF-I level was
used as an estimate of GH secretion, which might
also underestimate growth hormone deficiency (38)
as discussed above. It should also be pointed out that
reference values applied in this, as well as in previous,
studies may overestimate the true frequency of PiDs
in brain-injured populations, as recently discussed by
Klose & Feldt-Rasmussen (40). Finally, we did not
consider other factors that may impact on hormone
levels, as well as outcome, such as comorbidities,
pharmacological drug treatment, etc.
Conclusion
This study demonstrates that pituitary dysfunction
during the first year after TBI and aSAH may have
clinically relevant effects on clinical outcome at 12
months after the event, and lends further support to
the need for screening of pituitary dysfunction after
TBI and aSAH. The findings also point to the need
for further studies to improve clinical management
of these patients and may be useful for the design of
larger prediction studies.
ACKNOWLEDGEMENTS
This study was supported by a grant provided by grants from
Stockholm County Council (ALF-grants), Lars Hedlund (Ka-
rolinska Institutet Dnr 2-1582/2016), NovoNordisk, and partly
by a grant from Pfizer, Sweden. The authors thank Johan Bring,
Statisticon, for most valuable statistical advice.
271
The authors have no conflicts of interest to declare
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