Efficacy of perioperative dexmedetomidine in postoperative neurocognitive function: a meta-analysis.

Neuroprotective effects of dexmedetomidine are reported in preclinical and clinical studies but evidence regarding the postoperative neurocognitive function is not as clear. This study performed a meta-analysis on outcomes of studies which examined neurocognitive performance by using valid assessment tools before and after perioperative dexmedetomidine treatment. Literature was searched in several electronic databases and studies were selected by following précised inclusion criteria. Meta-analyses of mean differences in percent changes from baseline in neurocognitive assessment scores were carried out and subgroup analyses were performed. Eighteen studies were included. Initial dose of dexmedetomidine (mean ± SD) was 1.28 ± 0.97 μg/kg and maintenance dose was 0.41 ± 0.11 μg/kg per hour. In healthy volunteers, there was no significant difference in the neurocognitive performance between dexmedetomidine and controls/comparators (mean difference (95% confidence interval (CI)): -12.72 (-50.25, 24.80) %; P = 0.51). Perioperative dexmedetomidine treatment was associated with significantly better neurocognitive performance in comparison with saline (mean difference (95% CI): 9.10 (3.03, 15.16) %; P = 0.003) as well as with comparator anaesthetics (mean difference: 5.50 (0.15, 10.86) %; P = 0.04) treated patients. In the submeta-analyses of studies which utilized neurocognitive assessment tools other than Mini-Mental State Examination (mean difference: 6.66 (-3.42, 16.74); P = 0.20) or studies with patients under 60 years of age (mean difference: 7.48 (-3.00, 17.96); P = 0.16), the differences were not significant between dexmedetomidine- and saline-/comparator-treated patients. Perioperative dexmedetomidine treatment is associated with significantly better neurocognitive function postoperatively in comparison with both saline controls and comparator anaesthetics (predominantly midazolam).