Extended Lake Louise Score: a novel standard evaluation of cognitive impairment for immigrants' rapid ascent to high altitude

Objective

To extend the Lake Louise Scoring (LLS) system to better assess cognitive impairment, and investigate the early changes of hematological indicators for subjects of rapid ascent to high altitude.

Methods

One hundred and eighty-nine subjects underwent routine hematology, urine and psychological examination at the altitude of 1500 m in February, and did that again after they had ascended to 3860 m in 2 days. Subjects were evaluated with eLLS using a combination of self-reported cognitive assessment and a diagnosis of AMS based on 4-item Lake Louise Score (LLS) of Acute Mountain Sickness (AMS). Next year, a follow-up validation was conducted in the same area.

Results

Sixty-eight subjects were diagnosed AMS with LLS and 92 subjects met the diagnostic criteria of eLLS among 189 subjects. The difference in hematological indicators calculated by the eLLS criteria was more significant than that calculated by the LLS criteria, which including red blood cells (P < 0.01), white blood cells (P < 0.05), hemoglobin (P < 0.01), platelets (P < 0.01) and neutrophils (P < 0.01). The eLLS identified additional risk factors comparing with LLS, which included higher white blood cells (OR 1.660, 95 % CI 1.032–2.670, P < 0.05), neutrophils (OR 1.312, 95 % CI 1.002–1.718, P < 0.05). Follow-up results showed that there were more significant differences in psychological scale scores between the groups identified using the eLLS criteria. (P < 0.05).

Conclusion

We proposed eLLS standard for individuals rapidly ascending to high altitude, which is more sensitive to hematological changes and can better reflect the cognitive mental state than the LLS.