This study has several limitations that warrant discussion. First, the cross-sectional study design with the sample size of 135—albeit representative for the entire cohort of 439—chronic TBI patients allows descriptive conclusions. But, a recent systematic review and meta-analysis on post-TBI HRQoL revealed that the majority of the included 49 studies between 1991 to 2013 analyzed less than 100 post-TBI patients [
33]. Two further TBI studies analyzed HRQoL of 60 and 51 patients 10 years after TBI, respectively [
22,
25]. Thus, the sample size of 135 chronic TBI patients in our study seems to be appropriate to highlight the need for psychiatric assessment on a regular base after TBI, especially when regarding the age range up to the 85-years-old, the long time period of up to 10 years after TBI as well as the given evidence, so far. Second, premorbid psychiatric sequelae, comorbidities, education, employment, living environment, injury patterns, and pharmacotherapy were not available. Third, neuroimaging data were not included to further characterize injury patterns as
i) patients were referred from different trauma centers to neurorehabilitation, i.e. neuroimaging was per se less comparable or not available,
ii) TBI patients—except for clinical deterioration or scheduling the bone flap replacement following decompressive craniectomy—do not get a routine neuroimaging while in neurorehabilitation,
iii) state-of-the-art imaging for DAI (diffusion tensor imaging (DTI), tractography and susceptibility weighted imaging using a gradient recall echo (GRE-SWI)) was not available at the time when most of our patients were injured, i.e. more than 10 years ago, and
iv) a multilevel diagnostic approach including neuroimaging and fluid biomarkers is recommended, but has not been implemented in the clinical routine, and thus were not available for our cohort [
48]. But, DAI does not seem to influence HRQoL up to 5 years after TBI, therefore the injury pattern itself might be a less relevant factor for long-term outcome [
49]. Fourth, functional status and comorbidities were not assessed in this survey-like cross-sectional study as written self-rating of functional status is most probably a less valid approach to get sustainable data. Fifth, caregiver’s quality of life and external assessments to elucidate a more objective perspective of the patients’ outcome was not done, but seem less relevant as indicated in the literature so far [
50,
51]. Sixth, although a total score below 60 on the QOLIBRI questionnaire indicates an increased risk of psychiatric sequelae, a precise cut-off score has not been established; accordingly, our results on psychiatric disorders must be interpreted with care, but might help to implement cut-off scores and highlight the need for further evidence. Seventh, the initial GCS was not documented in 38% of cases in our cohort—a well-known finding in previous studies [
25,
37]. Finally, the results’ generalizability might be limited due to the following issues:
i) the age span of 18- to 85-year-olds,
ii) the German population,
iii) the heterogeneity of TBI in our cohort, and
iv) treatment regimens including neurorehabilitation [
21,
22]. Nevertheless, age does not seem to be relevant for long-term outcome regarding HRQoL as the presented results are comparable to the large QOLIBRI validation study, that included 20 years younger patients on average [
38]. Future long-term outcome studies with larger sample sizes should better stratify for TBI severity subgroups beyond GCS as targeted by the large TRACK-TBI and CENTER-TBI studies. The acute TBI treatment in certified hospitals of the Southern Upper-Bavaria Trauma Network and the subsequent neurorehabilitation in one neurorehabilitation center—using standardized rehabilitation protocols—most probably represent the highest standard of medical care, and therefore results are at least generalizable within industrialized countries.