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Poorer sleep quality predicts melatonin response in TBI patients: findings from a randomized controlled trial.

STUDY OBJECTIVES
A recent clinical trial demonstrated that melatonin treatment was effective in improving self-perceived sleep quality in patients with TBI; however, it remains unclear which patients benefited from melatonin treatment. To that end, findings from the clinical trial were re-examined to identify possible predictors of treatment response.


METHODS
Hierarchical multiple regression was utilized to identify patient characteristics, TBI injury characteristics, and self-report measures assessing sleep, fatigue, mood, and anxiety symptomatology that may uniquely explain a change in self-reported sleep quality scores (follow-up minus baseline score) as assessed by the Pittsburgh Sleep Quality Index(PSQI).


RESULTS
After controlling for patient demographic and TBI injury-related variables, baseline self-report measures of sleep, fatigue, mood, and anxiety explained an additional 32% of the variance in change in PSQI scores. However, only baseline PSQI score made a unique and statistically significant contribution (β = -.56, p = .006). After controlling for patient and TBI characteristics, baseline PSQI scores further explained 27% of the variance in change in PSQI scores, R squared change = .27, F change (1, 27) = 11.79, p = .002). The standardized beta for baseline PSQI score revealed a statistically significant negative relationship with change in PSQI score (β = -.54, p = .002) revealing that higher PSQI score at baseline was associated with better sleep outcomes.


CONCLUSIONS
In a sample comprising predominately severe TBI and comorbid insomnia, participants who report poorer sleep quality have the most to gain from melatonin treatment irrespective of time since injury, demographics, fatigue, daytimes sleepiness, mood, and anxiety symptomology.


CLINICAL TRIAL REGISTRATION
The manuscript reports on a clinical trial which was prospectively registered with the Australian New Zealand Clinical Trials Registry on the 13th of July, 2011. Identifier: ACTRN12611000734965 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=343083&showOriginal=true&isReview=true.