Thirteen observational studies were included in the review. Sample sizes ranged from 24 to 830 patients. Six studies were retrospective. Eleven studies used a historic control group. Downs and Black quality scores ranged from 9 to 20, out of 32. Common problems included lack of power, risk of confounding and study reporting.
The use of management protocols was associated with a favourable neurological outcomes (as defined by Glasgow Outcome Scale scores) at six months (OR 3.84, 95% CI 2.47 to 5.96; Ι²=33%; five studies) but not at 12 months (one study). Use of management protocols was associated with reduced mortality at hospital discharge (OR 0.74, 95 % CI 0.47 to 1.15; Ι²=81%; eight studies) and six months (OR 0.33, 95 % CI 0.13 to 0.82; Ι²=68%; four studies), but not at 12 months (one study). Exclusion of the three studies with clear co-interventions increased the size of effect and removed the heterogeneity from the analyses for neurological outcomes at six months and mortality at six months (both Ι²=0%). Meta-regression analyses were not possible due to the small number of included studies.
Further results were reported in a narrative synthesis.